Oxygen electrocatalysis plays a pivotal role in energy conversion and storage technologies. The precise identification of active sites for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial for developing an efficient bifunctional electrocatalyst. However, this remains a challenging endeavor. Here, it is demonstrated that metal?free N?doped defective carbon material derived from triazene derivative exhibits excellent bifunctional activity, achieving a notable ?E value of 0.72 V. Through comprehensive X?ray photoelectron spectroscopy and Raman spectroscopic analyses, the active sites responsible for oxygen electrocatalysis are elucidated, resolving a long?standing issue. Specifically, pyridinic?N sites are crucial for ORR, while graphitic?N are good for OER. A predictive model utilizing ??electron descriptors further aids in identifying these sites, with theoretical insights aligning with experimental results. Additionally, in situ ATR?FTIR spectroscopy provides clarity on reaction intermediates for both reactions. This research paves the way for developing metal?free, site?specific electrocatalysts for practical applications in energy technologies

Metal molybdates (M?MoO4, M = Fe, Co, and Ni) are recognized as active catalysts for water-splitting reactions. However, their poor electronic conductivity and low intrinsic activity hamper overall water-splitting activity and durability, limiting their widespread applications. Herein, the influence of lanthanum doping on the electrocatalysis of CoMoO4 toward overall water-splitting activity and durability in high-pH media was investigated. Varying La-dopant percentages in the CoMoO4 lattice tuned the electrocatalytic activity, and optimal performance was achieved at 5% La_CoMoO4 for hydrogen (?20 at 0.219 VRHE) and oxygen evolution reactions (?20 at 0.272 VRHE). Notably, La doping in CoMoO4 mitigated significant MoO42? leaching in the electrolyte, maintaining excellent structural integrity and demonstrating high durability for over 45 h in a two-electrode system, demanding a cell potential of only 1.68 V toward overall water splitting in 1 M KOH. Structural characterizations and in situ Raman studies established a dynamic surface reconstruction of active components toward the HER/OER. DFT analyses proved the modified electronic structure of CoMoO4 through La doping, effectively optimizing adsorption energies of reactive hydrogen and oxygen intermediates and boosting the intrinsic activity of CoMoO4 toward hydrogen and oxygen evolution reactions (HER/OER). This work depicts the prospect of rare-earth metal incorporation in non-noble metal-based electrocatalysts to design highly efficient and durable electrocatalysts for electrochemical applications.

Electrochemical reduction of nitrate to ammonia using electrocatalysts is a promising alternative strategy for both wastewater treatment and production of green ammonia. Numerous tactics have been developed to increase the electrocatalyst's NO3RR activity. Herein, we report a unique molecular alignment-dependent NO3RR performance using ?-CuPc and ?-CuPc nanostructures as effective electrocatalysts for the ambient synthesis of ammonia. The well-aligned ?-CuPc demonstrated an impressive ammonia yield rate of 62 703 ?g h?1 mgcat?1 and a Faradaic efficiency of 96%. In contrast, the less well-aligned ?-CuPc exhibited a yield rate of 36 889 ?g h?1 mgcat?1 and a Faradaic efficiency of 61% at ?1.1 V vs. RHE under the same conditions. Scanning tunneling microscopy/spectroscopy (STM/S) confirms that the well-aligned ?-CuPc exhibits superior transport properties due to optimal interaction of the Cu atom with the nitrogen atom of parallel molecules (d?–p?) in its one-dimensional nanostructure, which is clearly reflected in the electrocatalytic performance. Furthermore, theoretical research reveals that the NO3RR is the predominant process on the ?-CuPc catalyst in comparison to the hydrogen evolution reaction, which is verified by gas chromatography, with ?-CuPc exhibiting weaker binding of the *NO intermediate at the copper site and a lower overpotential, hence facilitating the NO3RR relative to ?-CuPc

The rate of tetracycline (TC) production and consumption has tremendously increased lately for the treatment of infectious diseases in humans and animals. Their release into the environment through overuse and improper disposal practices has raised serious concerns for the ecosystem deliberating the significance of easy detection approaches towards TC. By virtue of the excellent physical and chemical attributes of Metal-Organic frameworks (MOFs), a Tb-doped MOF was developed for the selective and accurate detection of TC. Remarkably, the strong green luminescence of Tb3+ is quenched efficiently with TC even in the presence of other antibiotics. The sensor material exhibits a highly sensitive turn-off response with an exceptionally low limit of detection of 0.07 ?M and a quenching constant value of 1.68 × 104 M-1. The mechanisms for selective quenching of fluorescence towards TC are investigated in detail using theoretical calculations and simulations to demonstrate the occurrence of electron transfer within the system. The detection behavior is also tested with river water samples collected from Chennai rivers which exhibited an excellent recovery of results qualifying Tb@ZB as a promising candidate to be developed into a prototype device to enable facile rapid analysis in real-time samples. The sensing approach provides a crucial ground for monitoring the presence of TC with 87–101 % reliability in wastewater systems

Integration of different active sites by heterostructure engineering is pivotal to optimize the intrinsic activities of an oxygen electrocatalyst and much needed to enhance the performance of rechargeable Zn–air batteries (ZABs). Herein, a biphasic nanoarchitecture encased in in situ grown N?doped graphitic carbon (MnO/Co?NGC) with heterointerfacial sites are constructed. The density functional theory model reveals formation of lattice oxygen bridged heterostructure with pyridinic nitrogen atoms anchored Co species, which facilitate adsorption of oxygen intermediates. Consequently, the well?designed catalyst with accessible active sites, abundant oxygen vacant sites, and heterointerfacial coupling effects, simultaneously accelerate the electron/mass transfer and thus promotes the trifunctional electrocatalysis. The assembled aqueous ZAB delivers maximum power density of ?268 mW cm?2 and a specific capacity of 797.8 mAh gzn?1 along with excellent rechargeability and extremely small voltage gap decay rate of 0.0007 V h?1. Further, the fabricated quasisolid?state ZAB owns a remarkable power density of 163 mW cm?2 and long cycle life, outperforming the benchmark air?electrode and many recent reports, underlining its robustness and suitability for practical utilization in diverse portable applications

Utilizing renewable sources of energy to produce hydrogen by electrocatalytic water splitting has emerged as an achievable answer to the issues associated with fossil fuels. Designing an efficient electrocatalyst for hydrogen evolution reaction (HER) is an important research area and it is essential to develop the catalyst that is electrocatalytically active, stable and economical to overcome the use of high-cost Pt for HER reaction. In this regard, we have synthesized a novel graphitic carbon nitride-based Schiff base modified silane linked palladium (II) nanocatalyst (g-C3N4-Scb@Pd). The g-C3N4-Scb@Pd evaluated for electrocatalytic hydrogen evolution reaction showed excellent catalytic activity exhibiting lowest overpotential of 40.3 mV at 10 mA/cm2 compared to its other counterparts such as g-C3N4-Pd and g-C3N4. The enhanced activity of g-C3N4-Scb@Pd can be ascribed to higher tendency for charge transfer contributed by Schiff base modified silane bonding between Pd and g-C3N4 forming efficient pathway for improved electron migration in addition to synergistic effect of Pd and g-C3N4. Further, the DFT analysis identifies the active sites, electronic structures and analyses the underlying phenomena to elucidate the possible reason for improving the HER performance from g-C3N4 towards Pd@g-C3N4. This work introduces a new approach for designing and engineering the g-C3N4 based efficient electrocatalysts

Strategic alteration of the chelating atoms around the metal center can modify the electronic band structure of the electrocatalyst, improving its performance in oxygen evolution and reduction reactions (OER/ORR). Advancements in the development of catalysts with heteroatoms and axial modifications in the coordination sphere are mostly limited to single?molecule electrocatalysts or elevated temperature?mediated pyrolysis approaches for oxygen electrocatalysis. Inspired by biological catalytic systems with axial coordination, a pyrolysis?free strategic methodology is adopted for the synthesis of an iron?metaled covalent organic polymer matrix axially laminated over cobalt?based metal?organic framework through an imidazole moiety. Precise engineering of coordination atoms in synthesized core?shell material, featuring dual metal sites with distinct neighboring atom exhibits mutual synergy due to the presence of bridging imidazole moiety between two metal sites. Modulated synergism navigates the electronic structure such that it favors specific reactant adsorption on specific metal sites during bifunctional O2 electrocatalysis as confirmed through in situ Raman spectroscopy and in situ attenuated total reflection infrared (ATR?IR) spectroscopy. Through dynamic correlation between the in?situ studies and modified d?band center obtained theoretically, the pivotal role of axial coordination linkage mediated synergism favoring ORR/OER process via target?specific reactant adsorption is demonstrated

The electrochemical nitrogen reduction reaction (NRR) has garnered much attention, but the major challenge remains with efficient electrocatalysts. Metal-free carbonaceous materials, doped with heteroatoms and structural defects, present a promising alternative to metal-based catalysts. This study introduces a novel strategic stepwise synthesis strategy of defective nitrogen-doped carbon material, further doped with secondary heteroatoms boron and fluorine (FBDG). These secondary atoms in combination create additional active sites for nitrogen adsorption and activation and suppress the hydrogen evolution reaction (HER). The synergistic effect of three heteroatoms and induced defects in the catalyst enhances electron-donor behavior, improving ? bonding within the carbon framework and facilitating the electron transfer processes during NRR, resulting in a significantly high Faradaic efficiency of 38.1% in the case of metal-free electrocatalysts. The theoretical calculation reveals that FBDG possesses a sufficient charge density to reduce nitrogen at a low overpotential following an alternating free energy pathway. The reaction intermediates are thereby identified by in situ ATR-FTIR studies. For the rapid screening of ammonia, we used a rotating ring disk system (RRDE) and did a kinetic study. The high efficiency, stability, and cost-effectiveness of FBDG position it as a strong contender for sustainable ammonia production and pave the way for future advancements in NRR

Research often focuses on improving cathode materials to boost the energy density of charge storage devices to levels comparable to batteries, while anode materials have been less frequently explored. This work presents the iron oxide/reduced graphene oxide (Fe2O3/rGO) composite synthesis by a one-pot hydrothermal method for possible utilization as an anode material in battery applications. The crystalline Fe2O3 nanoparticles were allowed to grow over two-dimensional (2D) rGO sheets as a growth template using the hydrophilic groups as nucleation centers. The unique structure of Fe2O3/rGO composites significantly enhances ion transport efficiency, optimizing active materials’ utilization and thus improving overall performance in energy storage applications. The optimized Fe2O3/rGO-3h composite electrode demonstrates an excellent specific capacity of 233 mAh g–1 at a current density of 2 A g–1. The flexible ASSC device shows a high capacity of 41 mAh g–1 at a current density of 1 A g–1 with an energy density of 27.8 Wh kg–1 at a power density of 750 W kg–1. Furthermore, cyclic voltammetry (CV) and galvanostatic charge–discharge (GCD) curves of flexible devices remained stable upon bending up to 180° and during series or parallel connections. A laboratory prototype of a CR-2032 coin-type ultracapacitor can power a blue, red, green, and yellow LED to run continuously on just one charge. Further, density functional theory (DFT) was employed to investigate the charge transfer, electronic structure, and binding interactions of Fe2O3/rGO composites, elucidating their potential as high-performance anode materials for supercapacitors. This work unlocks an avenue for designing and fabricating Fe2O3/rGO composites as promising anode materials by utilizing rGO as a template for the next generation of supercapacitors with improved energy storage performance

A significant research gap in the field of synthesis of single atom catalysts (SACs) is addressed by developing a low-temperature complexation approach to stabilize the single metal atoms on stacked polytiazine matrix (g-C3N4) with a good metal loading. Unlike conventional high-energy (400-700 °C) and time-intensive (120-300 min) methods typically used for embedding SACs in g-C3N4 matrices, the present synthesis utilizes a facile, microwave-assisted method that operates at a low temperature of 140 °C and completes within 30 min. Comprehensive analysis reveal that complexation of the Cu2+/Cu+ ions with nitrogen in the polytriazine structure facilitates layer stacking. Specifically, Cu? ions promote sheet formation in co-ordination with two nearby N atoms, while Cu2+ ions stabilize the stacked layers of the polytriazine framework through co-ordination with four N atoms. The resulting SAC exhibits a Cu metal loading up to 3.5 wt.%, with a specific surface area (SABET) of 330 m2 g-1 and pore size distribution centered at 1.9 and 5 nm. The SAC demonstrates excellent catalytic performance for click cycloaddition reactions under base-free conditions, with a high turnover frequency (TOF) of 120 h-1, a broad substrate scope, and reusability across seven cycles without detectable Cu leaching, making it a promising SAC for triazole synthesis

Advancing energy storage and conversion research on 2D nanostructures hinges on the critical development of bifunctional electrodes capable of effectively catalyzing oxygen evolution reactions and facilitating charge storage applications.

Glycerol, a by?product of biodiesel production, and CO2, a major greenhouse gas, are abundant but underutilized feedstocks. Their simultaneous conversion into formic acid and lactic acid presents an innovative and sustainable approach to addressing environmental challenges. Formic acid, a versatile compound in multiple industries, and lactic acid, a versatile platform chemical used in food, pharmaceuticals, and biodegradable plastics, hold immense commercial value. In this work, a NiO?ZrO2 catalyst synthesized through incipient wetness impregnation is employed to achieve the simultaneous conversion of CO2 and glycerol in an alkaline medium. Comprehensive characterisation of the catalyst using PXRD, Raman spectroscopy, XPS, BET surface area, CO2/NH3?TPD, H2?TPR, and UHR?TEM analysis revealed its unique properties, including weak Lewis acid sites critical to its performance. Under optimal reaction conditions, 200 °C, 40 bar CO2, and KOH as the base, the catalyst achieved yields of 3.26 mmol of formate and 11.20 mmol of lactate. The synergistic interaction between NiO and ZrO2, along with the in situ formation of carbonate salts, is key to the high efficiency. An initial economic assessment demonstrates the commercial viability of co?producing formic and lactic acid, with the glycerol price and the efficiency of converting the formate and lactate salts to the corresponding acids being critical factors for the economic feasibility of the process.

Designing suitable heterojunctions effectively addresses challenges like rapid electron-hole recombination, limited mobility, restricted absorption, and insufficient active sites. Thus to improve the photocatalytic performance, we synthesized a p-n heterojunction photocatalyst, Co3O4/NiCo2O4@Mn0.2Cd0.8S, by coupling ZIF-67-derived p-type Co3O4/NiCo2O4 double-shelled nanocages with n-type Mn0.2Cd0.8S nanoneedles via a template-assisted method. Analytics revealed the judicious anchoring of the Mn0.2Cd0.8S over the Co3O4/NiCo2O4 surface, reinforcing the photocatalytic activity. The resultant heterostructure exhibits superior photocatalytic performance, achieving an HER rate of ?14.34 mmol h?1 g?1 with an AQY of ?35.1 %. This represents an enhancement of ?72-fold compared to pristine Mn0.2Cd0.8S. The synergistic interplay within the heterostructure, facilitated by abundant active sites, enhanced light absorption, and an efficient charge transfer channel at the p-n heterojunction interface, promotes efficient photoexcited charge separation and transfer. Furthermore, the DFT calculations reveal that the incorporation of NiCo2O4 and Mn0.2Cd0.8S into the Co3O4 framework significantly reduces the HER overpotential from |?GH| = 0.32 eV for pristine Co3O4 to 0.20 eV for the Co3O4/NiCo2O4@Mn0.2Cd0.8S heterostructure. This enhancement is attributed to the optimized charge distribution at the active sites and a downward shift in the d-band centre from ?2.15 eV to ?2.30 eV, which weakens the adsorption of reaction intermediates, thereby accelerating HER kinetics.

The electrocatalytic CO2 reduction reaction (CO2ER) has sparked immense interest due to its potential to generate valuable multi-carbon (C2) products. The innovative dual active site catalysts (DACs) feature dual-atom sites that create the perfect geometric environment for two CO molecules to bond simultaneously. In this study, we spotlight transition metal (TM) dimers anchored on nitrogen-doped graphene, referred to as TM1TM2@NGr, as our primary focus. Analysing 54 candidates, we evaluate their stability via negative binding energy and ICOHP values, enhanced by ab initio molecular dynamics (AIMD) calculations. Three systems namely WIr@NGr, WFe@NGr, and WW@NGr demonstrate remarkable selectivity for ethanol production due to their low free energy difference (?G*CO dimer–2*CO) which offers low overpotentials of 0.47, 0.49, and 0.5 V, respectively. We analysed 71 electronic parameters to identify key factors influencing the free energy difference (?G*CO dimer–2*CO) and found 12 electronic descriptors strongly correlated due to the Pearson correlation coefficient (r) being larger than 0.8. Among these, the occupancy of the dxz orbital (dxz_occ) and the downward channels of dxz and dz2 orbitals (dxz_down_occ and dz2_down_occ) were the most effective for predicting the energy difference, demonstrating the highest r values. This highlights their importance as key descriptors for ?G*CO dimer–2*CO and corresponding C2 production. Furthermore, three DACs have been identified as highly effective for hydrogen evolution reactions (HER), while thirteen DACs show CO2ER to methane production. Our research offers vital insights into the catalytic mechanisms of DACs, paving the way for discovering cost-effective candidates for efficient CO2 conversion into valuable C2 products.

Transition-metal hydroxides have attracted significant interest as electrode materials for supercapacitors due to their abundant redox activity and excellent electrical conductivity. Herein, we present a novel design and engineering of a hexagonal thin nanosheet of cobalt hydroxide (Co(OH)2) with enveloped imidazolium-based poly(ionic liquid)s (PIL-Br, poly(1-butyl-3-vinylimidazolium bromide)). The presence of PILs in Co(OH)2 influenced morphogenesis control and a high capacitance of 1758 F g?1 at a current density of 2 A g?1 in a three-electrode system. A solid-state free-standing device was developed with a unique electrolyte configuration comprising EMIM-TFSI/PVDF-HFP, which further enhanced device performance. Achieving a high energy density of 212 W h kg?1 at a power density of 1499 W kg?1 underscored its capability to deliver stored energy effectively. Most notably, the device demonstrated exceptional durability, maintaining a capacity retention of 97% even after undergoing 10 000 cycles at 5 A g?1. Density functional theory also indicated the presence of PILs active sites in the composites, thereby promising a new in situ strategy for energy-storage applications.

Earth?abundant transition metal?based catalysts with exceptional bifunctionality for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are greatly desired. Alloyed catalysts, such as molybdenum?nickel (MoNi), are known to demonstrate enhanced HER activity, yet suffer from low OER performance. To realize improved functionality, elemental doping can be an effective approach, giving rise to synergistic interactions between incorporated metal species, optimizing surface adsorption of target intermediates, and promoting reaction. Herein, the enhanced OER performance of the MoNi catalyst while simultaneously boosting HER activity via incorporating a small amount of iron and chromium into MoNi (Mo?Ni(FeCr)) is demonstrated. For an optimized Mo?Ni(FeCr) catalyst, in 1.0 m potassium hydroxide electrolyte, an overpotential of only 11 and 179 mV for HER and OER, respectively, are required to afford a current density of 10 mA cm?2. For the overall water splitting, a current density of 20 mA cm?2 is reached at 1.489 V. The DFT calculations demonstrated that the inclusion of Fe and Cr in a molybdenum?nickel catalyst reduced the limiting potentials for both OER and HER, unlocking efficient bifunctionality activity for water splitting. These findings signify the improved electrocatalytic performance of, amongst the most active bifunctional electrocatalysts.

The development of direct methanol fuel cells (DMFCs) relies on designing replacements for benchmark platinum (Pt)?based electrocatalysts toward methanol oxidation reaction (MOR) that exhibit high resistance to CO poisoning, improve kinetic sluggishness, devoid of unwanted intermediates, low catalyst cost, and wide operating conditions. This study presents the development of defect engineering N?doped graphene oxide (NG) supported ZnWO4 nanocuboids as an efficient catalyst for photoelectrochemical MOR and electrochemical ORR. Under visible light (420 nm), the NG/ZnWO4 nanohybrid exhibits exceptional photoelectrochemical MOR with low potential of 0.5V with a high oxidation peak current density of ?10 mA cm?2 is recorded while comparing with benchmark catalyst Pt/C. In two electrode systems for DMFC, the catalyst reaches an impressive maximum power production of 111 mW cm?2 with very stable charge?discharge cycles of 0.33 mV cycle?1, which is far superior to ZnWO4’s alone. Simultaneously, the nanocomposite exhibits excellent ORR activity in alkaline medium with improved onset half?wave potential of 0.85V, high current density of 5.8 mA cm?2 at 1600 rpm, and robust stability, attributed to the synergistic effect between NG and ZnWO4. This work has reinforced these findings with theoretical insights using the Vienna Ab initio Simulation Package (VASP) to assess both PMOR and ORR performance and reaction intermediates.

Metal-organic frameworks (MOFs) offer excellent structural tuneability that enables selective host-guest interactions, but integrating them with conductive substrates like Ti3C2Tx MXene can reduce accessibility to functional groups. This work empirically analyzes the influence of synthesis strategy on the electrochemical performance of amino-functionalized IRMOF 3-MXene hybrids for dopamine (DA) sensing, restricting their availability for DA interaction and reducing sensing efficiency. In contrast, the post-synthetic hybrid retains free –NH? groups, enabling effective DA preconcentration, which allows subsequent electron transfer to the conductive Ti3C2Tx. This results in enhanced electrocatalytic response, with a synergistic index of 1.12, high sensitivity (263.8 µA mM?1 cm?2), and a low detection limit (56.4 nM) towards DA detection. The Schottky barrier formed at the MXene/IRMOF 3 interface modulates the charge transfer dynamics. Theoretical adsorption energy calculations further validate the experimental observations, highlighting the critical role of free and accessible functional groups in optimizing host-guest interactions for enhanced electrochemical performance.

Photocatalytic hydrogen (H2) production by mimicking natural light?harvesting complexes offers a sustainable route to solar fuel generation. Here, a pyridine?based homopolymer?chelated cobalt complex is reported as an efficient and stable catalyst for H2 production via water splitting. This study introduces a series of reversible addition?fragmentation chain transfer (RAFT)synthesized homopolymers with pyridine moieties that axially coordinate to a cobaloxime core. This study investigates the effect of linker position (meta vs para) on proton reduction affinity in cobaloxime catalysts. The catalysts demonstrate potential for H2 generation under visible light, with repetitive runs and maintain morphological integrity. Both photochemical and electrochemical H2 production results align with and reinforce the catalytic efficacy of the system, achieving an H2 generation rate of up to 42.99 mmol h?1 g?1 for P4VP?Co and 29.58 mmol h?1 g?1 for P3MP?Co in a neutral aqueous solution with a sacrificial electron donor. The superior electrochemical activity of P4VP?Co over P3MP?Co is due to the higher electroactive surface area in P4VP?Co. The density functional thoery (DFT) studies reveal the active site for the reaction and examine the role of homopolymers in enhancing H2 evolution reaction. This study presents a unique example of a cobaloxime core chelated with electron?donating polymers for renewable energy conversion applications.

Developing flexible, wearable, efficient, and self-powered electronic devices based on piezoelectric nanogenerators aspires to be a sustainable solution to renewable energy harvesting and storage. We report on a lead-free halide perovskite Cs3Sb2I9 and polyvinylidene fluoride (PVDF) based composite device capable of scavenging energy from routine biomechanical activities. Regulated incorporation and optimization of Cs3Sb2I9 into the PVDF matrix increased the electroactive phase of the device to ?82% with a piezoelectric coefficient of 7.48 pm V?1. The champion device produced an open circuit output voltage of 85 V and a current of 2.6 ?A. Furthermore, the device generated approximately ?1.26 ?W cm?2 of power density when connected to a 0.8 M? resistor, sufficient to operate portable electronic gadgets. We tested the device for its energy generation capabilities under simple human biomechanical movements such as hand hammering, finger tapping, elbow bending, knee bending, and toe pressing. To demonstrate the versatility of the nanogenerator device, we also tested its energy generation and storage capabilities by charging capacitors up to ?2.2 V. The device exhibited impressive durability and repeatability over 10 000 cycles, underscoring its potential as a promising solution for addressing the energy demand of portable and Internet of Things (IoT) devices through piezoelectric nanogenerators. Work function calculations using density functional theory demonstrated that the composite exhibited a reduced work function compared to individual components, indicating favorable electron emission characteristics. We also realized the piezo-phototronic effect in the composite using a self-powered photodetector, which exhibited an increment of 63% in the photocurrent, offering potential for piezotronic and optoelectronic devices

Single-atom catalysts (SACs) offer a promising strategy to enhance light utilization and charge carrier dynamics in photocatalytic hydrogen evolution. However, the uniform dispersion and stabilization of single-atom active sites remain significant challenges. Herein, we report the fabrication of atomically dispersed Cu and Ni dual-metal sites anchored on graphitic carbon nitride (CuNi–g-C3N4), achieving an outstanding hydrogen evolution rate of 1275 ?mol g–1 h–1 under visible light irradiation. The synergistic interaction between Cu and Ni bimetallic dual-atom catalysts (DACs) modulates the electronic structure of g-C3N4, creating active sites and suppressing charge recombination, as confirmed by density functional theory (DFT) calculations. X-ray absorption spectroscopy (XAS) analysis verifies the atomic dispersion of the Cu and Ni sites, revealing their interactions with the carbon nitride framework. Photoluminescence (PL) spectroscopy and electrochemical impedance spectroscopy (EIS) further demonstrate enhanced charge separation and reduced recombination in CuNi–g-C3N4. The catalyst exhibits excellent stability and maintains its photocatalytic activity over multiple reaction cycles, underscoring the potential of DACs for sustainable hydrogen production. This study provides insights into the rational design of dual single-atom catalysts for the efficient conversion of solar energy to hydrogen

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Eight electron nitrate (NO 3 – ) reduction to ammonia (NH 3 ) offers a cost–effective and energy efficient route than the Haber–Bosch process. The state of art electrocatalysts for nitrate reduction shows potential activity, albeit suffering from poor Faradaic efficiency, kinetically sluggish multi electron–proton process, and competitive hydrogen evolution reaction. Herein, we present a hollow iron phthalocyanine (FePc) rectangular nanotube (RNTs) electrocatalyst with 100 % Faradaic efficiency and 35067.09 µg h –1 mg cat –1 ammonia yield, which is 3.5 times higher than that of FePc nanorods. One-of-a-kind hollow nanostructure has Fe-N 4 active motif sites necessary for NO 3 – activation, dissociation, specific intermediate formation, and interaction, resulting in the energy-efficient generation of NH 3, according to in-situ research combined with theoretical analysis of molecular scale reaction mechanism. These unique results, coupled with the monitoring of pH changes in real time during electrolysis, open up new possibilities for progressive ammonia production with reduced carbon footprint.

Being a macrolide antibiotic, the antiviral and anti-inflammatory properties of azithromycin (AZM) were taken advantage of during the COVID-19 pandemic which led to the overuse of AZM resulting in excessive release and accumulation in the waterways and ecosystem causing unpleasant threats to humankind. This demands the necessity for a highly sensitive material being capable of recognizing AZM in wastewater. Mindful of the optical attributes of organic ligand structures, we have constructed a hybrid material by chelating Zn 2+ with pyridyl benzimidazole (PBI). The prepared sensor material ZnPBI was characterized using various microscopic and spectroscopic techniques including XRD, FT-IR, HR-SEM, HR-TEM, etc. The proposed sensor material exhibited proficient detection performance selectively towards AZM with a very low detection limit of 72 nM. Two linear ranges between 0 – 70 ?M and 70–100 ?M were observed corresponding to two different mechanistic pathways. To the best of our knowledge, the utilization of a metal-organic complex (MOC) for the fluorometric detection of AZM has not been explored so far. It is creditworthy to cite that the long-term structural stability of the sensor material was maintained for 100 days in water and it can be reused three times without any depreciation in the sensing activity. A combination of energy transfer routes, adsorption and electrostatic interactions for AZM detection are described experimentally and theoretically which provides insights into the role of MOC as sensing probes.

To restrain fossil fuel depletion, the need of the hour is the development of efficient, durable, and non-precious electrocatalysts for the hydrogen evolution reaction (HER). The hierarchical nanostructure consisting of transition metal dichalcogenides and graphitic heteroatom-doped carbon with an abundant interfacial M–N–C catalytic site is highly demanding for electrolytic applications. Herein, we report crystallinity-engineered ultrathin MoS 2 nanosheets hierarchy over nitrogen-doped graphitic carbon (NC) hollow spheres as a promising material for HER. The well optimized NC@MoS 2 demonstrates superior HER activity with a low onset overpotential of 9 mV and an overpotential of 145 mV at a current density of ?10 mA cm ?2. It exhibits low Tafel slope of 39 mV dec ?1 and excellent chronoamperometric stability. Superior HER activity originates from interfacial Mo–N–C bonds. Density functional theory (DFT) calculations unveil that Mo–N–C bonds between MoS 2 and NC matrix ease electronic transportation and further diminish Gibbs free energy for HER.

The electrochemical reduction of nitrate to ammonia (NORR) catalyzed by metal organic frameworks (MOFs) is a promising and efficient method for reducing nitrate pollution in water while simultaneously producing a valuable product, ammonia. Herein, we report the 3D nanoarray architecture of the metal organic complex Fe-(tetracyanoquinodimethane) Fe(TCNQ) as an efficient electrocatalyst that exhibits a high ammonia yield rate of 11 351.6 ?g h cm and faradaic efficiency (FE) of 85.2% at ?1.1 V vs. RHE and excellent catalytic stability up to 2 days. The excellent catalytic performance is evaluated by ATR-FTIR spectroscopy and a series of control experiments. Density functional-based theoretical calculations are carried out to identify Fe-N active sites in metal-organic network structures. This study showcases the advancement of transition metal-based organic frameworks as very effective electrocatalysts for the reduction of nitrate to ammonia (NH).

Lead halide perovskite (LHP) nanocrystals (NCs) offer an easy tunability of band gap via anion exchanges, enabling their usage in tandem optoelectronic devices with graded band gaps. However, instantaneous anion migrations at the interfaces of different LHP layers impede the formation of well-defined interfaces. We deposited an ultrathin alumina (AlO) layer at the interface of CsPbBr-CsPbI NC films by using atomic layer deposition (ALD) and demonstrated that low-temperature ALD alumina has negligible impact on the structural or optical properties of CsPbBr NCs except agglomeration. ALD alumina can restrict anion migration for months but cannot be prevented permanently. The rate of anion migration significantly decreases with an increase in the AlO layer thickness on CsPbBr NC films, which follows first-order kinetics. Density functional theory (DFT) calculations showed that the iodide ion can migrate through oxygen vacancies in the AlO layer with an activation energy of 1.54 eV. This strategy provides new insight into fabricating halide perovskite-based tandem optoelectronics devices.

Lithium-ion batteries (LIBs) have transformed our envisioned future into a reality where induction motor engines power electric vehicles (EVs). While LIBs offer impressive advantages compared to other energy storage systems for EVs, they face practical deployment challenges in performance, cost, and scalability. One critical component of LIBs that has garnered significant attention is the cathode, primarily due to its high cost, stemming from expensive cobalt metals and limited capacity, which cannot meet the current demand. However, layered lithium nickel cobalt manganese oxide (NCM) materials have achieved remarkable market success. Despite their potential, much current research focuses on experimental or theoretical aspects, leaving a gap that needs bridging. Understanding the surface chemistry of these oxides and conducting operando observations is crucial. Combining advanced surface analysis techniques with theoretical calculations ( viz., quantum mechanics) is proposed to bridge this knowledge gap. This review delves into recent performance achievements ( viz., projected driving performance, current EVs model, and battery specifications), challenges, and opportunities associated with various NCM materials as cathode materials. It also explores cutting-edge developments in experimental and theoretical techniques that analyze battery operations, address frontier challenges, and provide novel insights. Furthermore, the review comprehensively discusses the concept of single-crystal (SC) NCM and its practical implications in EVs. Finally, the review provides an outlook on future guidelines for designing NCM cathodes for LIBs, emphasizing the convergence of experimental and computational/theoretical approaches to achieve superior performance.

Oxygen vacancy engineering has recently been gaining much interest as the charging effect it induces in a material can be used for varied applications. Usually, semiconductor materials act poorly in electrocatalysis, particularly in the nitrogen reduction reaction (NRR), owing to their inherent charge deficit and huge band gap. Vacancy introduction can be a viable material engineering route to make use of these materials for the NRR. However, a detailed investigation of the vacancy-type and its role for the structural reorientation and charge redistribution of a material is lagging in the field of NRRs. This work thus focuses on the synthesis of oxygen vacancy-engineered SnO with a gradual structural transformation from in-plane (io) to bridge-type oxygen vacancy (bo) density. Consequently, the electron occupancy of the spd hybrid orbital changes, leading to an upshifted valence band maxima towards the Fermi level. This has a profound effect on the nature of N adsorption and the extent of N ? N bond polarization. Sn atoms adjacent to the bo are found to have a fair density of dangling charges that accomplish the NRR process at a comparatively low overpotential and determine the binding strength of the intermediates on the active site. The obscured yet stable reaction intermediates are thereby identified with in situ ATR-IR studies. A restricted hydrogen evolution reaction Faradaic on the Sn-site (favored over O-atoms) results in a Faradaic efficiency of 48.5%, which is better than that reported in all the literature reports on SnO for the NRR. This study thus unveils sufficient insights into the role of oxygen vacancies in a crystal as well as electronic structural alteration of SnO and the effect of active sites on the rate kinetics of the NRR.

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Fine control over the graphitization level of carbonized nanostructures can play a strategic role in tuning the crystallization of supported nanocatalysts, thereby modulating the kinetics of catalysis. However, realizing the synergistic interplay of graphitization-tunable support and supported catalysts poses a significant challenge. This study proposes a current pulse-induced ultrafast strategy for developing MOF-derived graphitic nano-leaves (GNL) and supported ultrafine ruthenium nanoclusters exhibiting selective crystallization states depending on the tunable graphitization level of GNL. The resulting ultrafine (?0.7 nm) amorphous-ruthenium nanoclusters linked with GNL (a-Ru@GNL) exhibit state-of-the-art performance in the hydrogen evolution reaction (HER), requiring very low overpotentials of only 23.0 and 285.0 mV to achieve current densities of 10 and 500 mA cm, respectively. Furthermore, a-Ru@GNL demonstrates exceptional operational stability for 100 h under high HER currents of 200 and 400 mA cm. Density functional theory reveals that the unique electronic structure of a-Ru and the cooperative effect of cobalt embedded in the graphitic layer lower the occupancy of the antibonding orbital, resulting in an accelerated HER process. Additionally, the unique electronic structure, highly conducting GNL, and efficient bubble release dynamics of super-aerophobic a-Ru@GNL contribute to reduced overpotentials, particularly at high HER current densities.

Ultrathin film of active materials having thickness <5 nm emerged as a promising candidate for miniaturized energy storage and conversion devices. However, the small lateral size restricts its real device applications. Herein, we report large area, 2D, ultrathin (thickness: 4.3 ± 0.3 nm) Co(OH) 2 nanosheets as bifunctional electrode material for supercapacitor and oxygen evolution reaction developed by ionic layer epitaxy method at the water-air interface. The symmetric supercapacitor device exhibited excellent volumetric capacitance of 2313 F/cm 3 at 0.4 mA/cm 2 current density. Additionally, it exhibited a remarkable volumetric energy density of 0.205 Wh/cm 3 at a power density of 0.145 W/cm 3, which is better than reported 2D electrode materials. Furthermore, the cobalt hydroxide (Co(OH) 2 ) ultrathin-film electrodes showed improved oxygen evolution reaction electrocatalytic activity with low overpotential (? 10, 330 mV) and Tafel slope (47 mV/dec). The structural and morphological investigations after long-term operations show substantial stability of the electrode material. The theoretical investigations of electronic structures, quantum capacitance, and free energy profiles for the oxygen evolution reaction mechanism corroborate the experimental results.

Water electrolysis to produce hydrogen (H) using renewable energy is one of the most promising candidates for realizing carbon neutrality, but its reaction kinetics is hindered by sluggish anodic oxygen evolution reaction (OER). Ruthenium (Ru) in its high-valence state (oxide) provides one of the most active OER sites and is less costly, but thermodynamically unstable. The strong interaction between Ru nanoparticles (NPs) and nickel hydroxide (Ni(OH)) is leveraged to directly form Ru–Ni(OH) on the surface of a porous nickel foam (NF) electrode via spontaneous galvanic replacement reaction. The formation of Ru?O?Ni bonds at the interface of the Ru NPs and Ni(OH) (Ru–Ni(OH)) on the surface oxidized NF significantly enhance stability of the Ru–Ni(OH)/NF electrode. In addition to OER, the catalyst is active enough for the hydrogen evolution reaction (HER). As a result, it is able to deliver overpotentials of 228 and 15 mV to reach 10 mA cm for OER and HER, respectively. An industry-scale evaluation using Ru–Ni(OH)/NF as both OER and HER electrodes demonstrates a high current density of 1500 mA cm (OER: 410 mV; HER: 240 mV), surpassing commercial RuO (OER: 600 mV) and Pt/C based performance (HER: 265 mV).

The Ostwald process, which is producing HNO for commercial use, involves the catalytic oxidation of NH and a series of chemical reactions conducted under severe operating conditions. Due to their energy-intensive nature, these activities play a major role in greenhouse gas emissions and global energy consumption. In response to the urgent requirements of the global energy and environmental sectors, there is an increasingly critical need to develop novel, highly efficient, and environmentally sustainable methods. Herein, CoPc/CN electrocatalyst, integrating CoPc nanotubes with CN nanosheets, is shown. The CoPc/CN electrocatalyst demonstrates yield rate of 871.8 µmol h g at 2.2 V, with corresponding Faradaic efficiency (FE) of 46.4% at 2.1 V, which notably surpasses that of CoPc. Through a combination of experimental investigations and density functional theory (DFT) calculations, this study shows that CoPc anchored on CN effectively simplifies the adsorption and activation of chemically inactive nitrogen molecules. The improved catalytic activity for composite system may be the reason of re-distribution of charges over the CoPc, tuning the valence orbital of Co center due to the presence of 2D layer of CN. This mechanism significantly lowers the energy barrier required for critical breaking of inert N, ultimately leading to a significant improvement in N oxidation efficiency.

Bifunctional electrode materials are highly desirable for meeting increasing global energy demands and mitigating environmental impact. However, improving the atom-efficiency, scalability, and cost-effectiveness of storage systems, as well as optimizing conversion processes to enhance overall energy utilization and sustainability, remains a significant challenge for their application. Herein, we devised an optimized, facile, economic, and scalable synthesis of large area (cm 2 ), ultrathin (?2.9 ± 0.3 nm) electroactive nanosheet of ?-Ni(OH) 2, which acted as bifunctional electrode material for charge storage and oxygen evolution reaction (OER). The ?-Ni(OH) 2 nanosheet electrode shows the volumetric capacity of 2.82 Ah.cm ?3 (0.82 µAh.cm ?2 ) at the current density of 0.2 mA.cm ?2. The device shows a high capacity of 820 mAh.cm ?3 with an ultrahigh volumetric energy density of 0.33 Wh.cm ?3 at 275.86 W.cm ?3 along with promising stability (30,000 cycles). Furthermore, the OER activity of ultrathin ?-Ni(OH) 2 exhibits an overpotential (? 10 ) of 308 mV and a Tafel value of 42 mV dec -1 suggesting fast reaction kinetics. The mechanistic studies are enlightened through density functional theory (DFT), which reveals that additional electronic states near the Fermi level enhance activity for both capacitance and OER.

Electrochemical nitrogen reduction reaction (e-NRR) is an eco-friendly alternative approach to generate ammonia under ambient conditions, with very low power supply. But, developing of an efficient catalyst by suppressing parallel hydrogen evolution reaction as well as avoiding the catalysts poisoning either by hydrogen or electrolyte ion is an open question. So, in order to screen the single atom catalysts (SACs) for the e-NRR, we proposed a descriptor-based approach using density functional theory (DFT) based calculations. We investigated total 24 different SACs of types TM?Pc, TM-NC, TM-NC, TM-NC and TM-N, considering transition metal (TM). We have considered mainly BF ion to understand the role of electrolyte and extended the study for four more electrolyte ions, Cl, ClO, SO, OH. Herein, to predict catalytic activity for a given catalyst we have tested 16 different electronic parameters. Out of those, electronic parameter d? occupancy, identified as electronic descriptor, is showing an excellent linear correlation with catalytic activity (R=0.86). Furthermore, the selectivity of e-NRR over HER is defined by using an energy parameter ?G-?G. Further, the electronic descriptor (d? occupancy) can be used to predict promising catalysts for e-NRR, thus reducing the efforts on designing future single atom catalysts (SACs).

Doping is considered a promising material engineering strategy in electrochemical nitrogen reduction reaction (NRR), provided the role of the active site is rightly identified. This work concerns the doping of group VIB metal in Ag3PO4 to enhance the active site density, accompanied by d-p orbital mixing at the active site/N2 interface. Doping induces compressive strain in the Ag3PO4 lattice and inherently accompanies vacancy generation, the latter is quantified with positron annihilation lifetime studies (PALS). This eventually alters the metal d-electronic states relative to Fermi level and manipulate the active sites for NRR resulting into side-on N2 adsorption at the interface. The charge density deployment reveals Mo as the most efficient dopant, attaining a minimum NRR overpotential, as confirmed by the detailed kinetic study with the rotating ring disk electrode (RRDE) technique. In fact, the Pt ring of RRDE fails to detect N2H4, which is formed as a stable intermediate on the electrode surface, as identified from in-situ attenuated total reflectance-infrared (ATR-IR) spectroscopy. This advocates the complete conversion of N2 to NH3 on Mo/Ag3PO4-10 and the so-formed oxygen vacancies formed during doping act as proton scavengers suppressing hydrogen evolution reaction resulting into a Faradaic efficiency of 54.8% for NRR. © 2024 Wiley-VCH GmbH.

A hybrid material comprising nickel hydroxide (Ni(OH)2) enveloped in a poly(ionic liquid) (PIL-Br), poly(1-butyl-3-vinylimidazolium bromide), is effectively employed as an additive in this study, wherein PIL-Br provides precise control over the shape and arrangement of Ni(OH)2 crystals. The PIL can chemically couple with the as-synthesized Ni(OH)2, imparting a modified surface electronic structure. This innovation introduces a fresh perspective for energy storage applications. Extensive characterization, along with density functional theory calculations, has explored the impact of PIL polymer groups. The findings indicate that these polymers facilitate a more favourable redox response on the surface of Ni(OH)2. The desired morphology of the nanoarchitectonics leads to a high performing solid-state free-standing device with 245 F g?1 specific capacitance at 1 A g?1. When integrated with an activated carbon electrode and a unique polyvinyl 1-butyl-3-methylimidazolium tetrafluoroborate/polyvinyl alcohol (BMIMBF4/PVA) configuration, the hybrid device achieves an ED of 86.2 W h kg?1 at a PD of 800 W kg?1. Profoundly, it retains a capacity retention of 96% even after undergoing 10 000 cycles at 5 A g?1. The utilization of stabilized nanoarchitectonics incorporating redox-active polymers marks a novel direction in various energy applications. © 2024 The Royal Society of Chemistry.

Effective integration of multiple active moieties and strategic engineering of coordinated interfacial junctions are crucial for optimizing the reaction kinetics and intrinsic activities of heterogeneous electrocatalysts. Herein, a simple integrated heterostructure of biphasic Co0.7Fe0.3/Fe3C embedded on in situ grown N-doped carbon sheets is constructed. Rationally designed CoFe/Fe3C-T2 owns more accessible active sites and interfacial junction effects, cooperatively boosting the electron and mass transfer, needed for multifunctional electrocatalysis. Leveraging the synergistic effect of dual active sites, CoFe/Fe3C-T2 demonstrates outstanding oxygen electrocatalytic activity in alkaline medium with an ultra-low potential gap of 0.58 V, surpassing the recently available state-of-the-art catalysts. Moreover, CoFe/Fe3C-T2 air-electrode achieves a high peak power density of 249 mW cm?2, a large specific capacity of 808 mAh g?1 and excellent cycling stability for aqueous Zn-air batteries. Remarkably, the solid-state flexible ZAB also exhibits satisfactory performance, showcasing an open-circuit voltage of 1.43 V and a peak power density of 66 mW cm?2. These outstanding results push this catalyst to the top of the list of non-noble metal-based electrode materials. This work offers a viable method for using the active-site-uniting strategy to create double-active-site catalysts, which may find real-time applications in energy conversion/storage devices. © 2024 Wiley-VCH GmbH.

Water-processable hybrid piezo- and thermo-electric materials have an increasing range of applications. We use the nanoconfinement effect of ferroelectric discrete molecular complex [Cu(l-phe)(bpy)(H2O)]PF6·H2O (1) in a nonpolar polymer 1D-nanofiber to envision the high-performance flexible hybrid piezo- and thermo-electric nanogenerator (TEG). The 1D-nanoconfined crystallization of 1 enhances piezoelectric throughput with a high degree of mechano-sensitivity, i.e., 710 mV/N up to 3 N of applied force with 10,000 cycles of unaffected mechanical endurance. Thermoelectric properties analysis shows a noticeable improvement in Seebeck coefficient (?4 fold) and power factor (?6 fold) as compared to its film counterpart, which is attributed to the enhanced density of states near the Fermi edges as evidenced by ultraviolet photoelectric spectroscopy and density functional based theoretical calculations. We report an aqueous processable hybrid TEG that provides an impressive magnitude of Seebeck coefficient (?793 ?V/K) and power factor (?35 mWm?1K?2) in comparison to a similar class of materials. © 2024 American Chemical Society.

Descriptors are properties or parameters of a material that are used to explain any catalytic activity both computationally and experimentally. Such descriptors aid in designing the material's properties to obtain an efficient catalyst. For transition metals, the d-band center is a well-known descriptor that shows a Sabatier type relationship for several catalytic reactions. However, it fails to explain the activity when considering the same metal active site with a varying local environment. To address this, density functional theory was used for single atom catalysts (SACs) embedded on armchair and zigzag graphene nanoribbons (AGNR and ZGNR). By varying the anchoring nitrogen atoms' orientation and considering pristine and doped cases, 432 active sites were used to test the oxygen evolution reaction (OER) activity. It was observed that S and SO2 dopants help in reducing the overpotential on Co-SAC (? = 0.28 V). Along with the d-band center, a total of 105 possible descriptors were individually tested and failed to correlate with the OER activity. Furthermore, PCA was employed to narrow down unique descriptors, and machine learning algorithms (MLR, RR, SVR, RFR, BRR, LASSO, KNN and XGR) were trained on the two obtained descriptors. Among the models, SVR and RFR models showed the highest performances with R2 = 0.89 and 0.88 on test data. This work shows the necessity for a multi-descriptor approach to explain OER catalytic activity on SACs and the approach would help in identifying similar descriptors for other catalytic reactions as well. © 2024 The Royal Society of Chemistry.

Electrocatalytic nitrogen oxidation reaction (N2OR) offers a sustainable alternative to the conventional methods such as the Haber–Bosch and Ostwald oxidation processes for converting nitrogen (N2) into high?value?added nitrate (NO3?) under mild conditions. However, the concurrent oxygen evolution reaction (OER) and inefficient N2 absorption/activation led to slow N2OR kinetics, resulting in low Faradaic efficiencies and NO3? yield rates. This study explored oxygen?vacancy induced tin oxide (SnO2?Ov) as an efficient N2OR electrocatalyst, achieving an impressive Faradaic efficiency (FE) of 54.2% and a notable NO3? yield rate (22.05 µg h?1 mgcat?1) at 1.7 V versus reversible hydrogen electrode (RHE) in 0.1 m Na2SO4. Experimental results indicate that SnO2?Ov possesses substantially more oxygen vacancies than SnO2, correlating with enhanced N2OR performance. Computational findings suggest that the superior performance of SnO2?Ov at a relatively low overpotential is due to reduced thermodynamic barrier for the oxidation of *N2 to *N2OH during the rate?determining step, making this step energetically favorable than the oxygen adsorption step for OER. This work demonstrates the feasibility of ambient nitrate synthesis on the soft acidic Sn active site and introduces a new approach for rational catalyst design.

Electrochemical carbon dioxide reduction reaction (CO2RR) to valuable fuels and chemical feedstock is a sustainable strategy to lower the anthropogenic CO2 concentration, thereby dynamising the carbon cycle in the environment. CH3OH on the other hand is undoubtedly the most desirable C1 product of CO2RR. However, selective electroreduction of CO2?to?CH3OH is very challenging and only limited catalysts are reported in literature. Pyrolyzing metal?organic frameworks (MOFs) to generate carbon matrix impregnated with metal nanoparticles, heralds exciting electrocatalytic properties. This study unveiled the morphological evolution of a mixed?ligand Ni?MOF (Ni?OBBA?Bpy) during pyrolysis, to generate Ni nanoparticles anchored 0D porous hollow carbon superstructures (Pyr?CP?800 and Pyr?CP?600). This unique morphology invokes high specific surface area and surface roughness to the materials, which synergistically facilitates the selective electroreduction of CO2?to?CH3OH. In comparison to most of the previously reported Ni electrocatalysts that mainly produced CO, Pyr?CP?800 selectively yielded CH3OH with Faradaic efficiency (FE) of 32.46% at ?0.60 V versus RHE (reversible hydrogen electrode) in 1.0 M KOH solution, which is highest among other reported Ni?based electrocatalysts in the literature, to best of our knowledge. Additionally, insights from density functional theory (DFT) calculations revealed that Ni (111) plane to be the active site toward the electrochemical. CO2?to?CH3OH formation.

Ammonia is one of the most essential raw materials for daily life applications. As an alternative to the Haber-Bosch process, scientists are focusing on an important domain of electrocatalysis for ammonia production. Herein, we approached a morphological adaptation of the electrocatalyst (iron phthalocyanine, FePc) based on hollow nanotube and rod types; the catalyst showed different N2-to-NH3 productivity. Under ambient conditions, FePc nanorods showed a good ammonia yield rate and Faradaic efficiency (FE) of 323.44 ?g h-1 mgcat.-1 and 23.33%, respectively, at ?0.4 V vs RHE in 0.05 M H2SO4. However, when the rod was adapted to a hollow nanotube structure by control of the temperature and time parameters, the ammonia productivity further improved. Under the same conditions, FePc nanotubes showed an excellent ammonia yield rate of 425.46 ?g h-1 mgcat.-1 and a corresponding FE of 23.61% at ?0.4 V vs RHE. In addition to experimental observations, theoretical analysis using density functional theory is also provided to establish the reaction mechanism of ammonia synthesis from nitrogen reduction reaction (NRR) using an FePc electrocatalyst. This work opens an avenue showing geometric structural induction of electrocatalytic activity toward future sustainable ammonia production

This study investigates the limited selectivity of the Cu111 surface for C–C bond formation during CO2 reduction and explores the factors influencing selectivity using Cu nanoparticles smaller than 2 nm. The optimal nanoparticle size for C–C bond formation on the 111 facet with minimal overpotential is determined using density functional theory. A suitable supporting surface to enhance the stability and catalytic performance of the Cu-based nanoparticles is identified. Various Cu catalyst geometries, including planar surfaces and cuboctahedral, icosahedral, and truncated octahedral Cu nanoparticles, are considered. Size-dependent effects on the binding energies of reaction intermediates and hydrogen atoms are examined. Carbon-based surfaces, particularly 2SO2-doped graphene nanoribbons, are stable hosts for the Cu nanoparticles and help in retaining the activity for CO2 reduction. Scaling relations between the binding energies of the intermediates suggest COOH binding energy as an energy descriptor. Through multiparameter optimization and with the help of parity line and graphical construction, Cu38 and Cu79 are found to be the most promising surface for C2 product generation. This study provides insights into the factors influencing the selectivity and catalytic performance of Cu nanoparticles, aiding the development of efficient catalysts for CO2 reduction

Producing molecular hydrogen (H) using water provides a sustainable approach for developing clean energy technologies. Herein, we report highly active ruthenium (Ru) clusters supported on iron oxide (Ru/FeO) and FeO/multi-walled carbon nanotubes (Ru/FeO/MWCNTs) by simple electrochemical deposition in a neutral aqueous medium. The supported catalyst exhibits good hydrogen evolution reaction (HER) activity in an acidic environment. Cyclic voltammograms (CVs) of potassium ferrocyanide (K[Fe(CN)]) confirm that MWCNTs enhance the electron transfer process by decreasing the redox formal potential. The overpotentials of Ru/FeO/MWCNTs and Ru/FeO electrocatalysts versus the reversible hydrogen electrode (RHE) were found to be 101 mV and 306 mV to reach a current density of 10 mA cm. As prepared, the catalyst displays good stability and retain its HER activity even after 1000 cycles. Furthermore, the stability of Ru/FeO/MWCNTs was studied using the chronopotentiometric (CP) technique for 12 h and found negligible loss in the catalytic activity towards the HER. To explore the role of Ru and underneath MWCNTs in improving the catalytic performance of FeO, density functional theory (DFT) calculations were carried out. DFT calculations indicate that the octahedral site of Ru/FeO favors the HER with a low overpotential. However, Ru/FeO/MWCNTs are more efficient towards the HER, which could be due to the availability of both octahedral and tetrahedral catalytic sites.

Carbon based electrocatalysts are well known promising candidates for the oxygen reduction reaction (ORR), but the random approach to find the best catalyst using experimental method delayed the screening process and it leads to a huge cost with less proficiency. Using Quantum Mechanics followed by Machine Learning (QM/ML) approach, we can predict the best catalyst faster way and the origin of the cause can be identified for further development of carbon-based catalyst. Using the ? electronic descriptor unveiled using density functional theory, we applied the analytical simple fit method and six different machine learning algorithms to develop a highly effective predictive model to estimate ?G OH. Furthermore, structural relations of ZGNR and AGNR are demonstrated to estimate the D ? (E F ), R-O ?, and ?G OH of different widths of ribbon that reduces additional DFT calculations. By applying both SVR predictive model and structural relations, we predicted the ORR performance of 2500 sites of GNRs and listed a few most ideal active carbon sites with lower overpotential (? < 0.5V). To validate our study, we predicted the ORR performance of different sites in 0D, 1D, 2D doped graphene systems using SVR model and confirmed the values with the DFT computed results.

Metal-free polymeric graphitic carbon nitride (CN) materials are robust and stable visible-light-driven photocatalysts that have recently piqued interest in photocatalytic applications. Its photocatalytic performance is restricted remarkably due to moderate oxidation ability and fast charge carrier recombination rate. To address these issues, we engineered carbon-vacant CN (FCN) using a facile formalin-assisted thermal polymerization of molten CN precursor in which the carbon vacancies (Cv) were regulated by altering formalin dosage. Consequently, FCN catalysts revealed Cv concentration-dependent sonophotocatalytic degradation of Tetracycline (TC) antibiotics over diverse water matrices. The optimal FCN exhibited complete TC degradation efficiency within 60 min with a synergy index of 1.4, which is approximately 2.6 times higher than that of pristine CN. The enhanced sonophotocatalytic performance was mainly due to the synergistic effect of ultrasound and light irradiation. The Cv formation also resulted in enhanced charge carrier transportation and facilitated oxygen adsorption at the Cv site of FCN - supported by both experimental study and theoretical calculation. Subsequently, FCN generated abundant reactive active oxygen species including, •O 2 –, as well as indirectly •OH which played a significant role in the degradation pathway and mineralisation of the TC molecules. This study provides insight into understanding the correlation between controllable defects and sonophotocatalytic degradation properties of the self-doped and deficient FCN.

This work presents decoration of Ru @ Fe 3 O 4 nanoparticles over conductive supports such as reduced Graphene Oxide (rGO) and Super P Carbon Black (SPCB) for hydrogen evolution reaction (HER). It is impressive that, low over potential of 148 mV at a current density 10 mA cm ?2 was achieved for the Ru@Fe 3 O 4 /rGO/SPCB composite. Density functional theory (DFT) endorses that, charge transfer can occur from underneath rGO layer to the Ru @ octahedral site of Fe 3 O 4 due to lower work function and higher Fermi energy level of rGO than Ru/Fe 3 O 4. Density of state calculations reveals that increase in the density of states of Ru/Fe 3 O 4 due to the layer of rGO in Ru/Fe 3 O 4 /rGO system.

An efficient synthesis of alkylboronate esters via alkyl halide borylation catalysed by copper nanoparticles stabilised on nitrogen-doped carbon nanotubes (N-CNT) is reported. This nanocatalyst provides practical access to alkylboronate esters at room temperature in 1 h, with good functional group tolerance. The procedure is also applicable to the borylation of benzyl chlorides and bromides. Radical clock experiments suggest that the reaction involves a radical pathway. The catalyst can be recycled up to ten runs without appreciable loss in the activity. In addition, we demonstrated the use of this supported copper catalyst for the anti-Markovnikov-selective hydroboration of vinylarenes and borylation of aryl halides with Bpin, providing alkyl- and arylboronate esters, respectively, in good to excellent yields.

CO production has grown throughout time because of unwanted chemical reactions; therefore, the design of efficient and stable catalysts with minimal metal loading is in demand in the automobile industry for CO oxidation. Herein, density functional theory is used to study the CO oxidation mechanism on single-atom catalysts (SACs) and metal-boron centered single metal dual site catalysts (SM-DSCs). It is observed that CO oxidation could follow Eley-Rideal (ER) mechanism on single-atom catalysts, such as MN4, MN3, MN2, and MN2op systems, where M is a 3d transition metal. Whereas in the case of SM-DSCs, the inclusion of Boron will make the Langmuir-Hinshelwood (LH) mechanism possible over ER mechanism with less chance of CO poisoning. The Brønsted?Evans?Polanyi (BEP) relations are proposed (as a function of oxygen atom binding) to identify the energy barriers (Ea 1 and Ea 2 ) for the release of the first and second CO 2 and O 2 adsorption energies for any new SM-DSCs system. Further microkinetic model is implemented on 30 SM-DSCs and found that PtBN2op and AgBN2 SM-DSCs own best catalytic activity with high Sabatier activity and Turnover frequency for CO 2 production. Hence, this work provides an approach toward the possibility of LH mechanism in the class of single-metal atom-based catalysts.

One of the promising approaches to synthesize ammonia in ambient conditions is through artificial photocatalytic nitrogen fixation. In order to overcome the hassles of charge carrier recombination and finite light response of photocatalysts, high charge separation efficiency and a wide window for optical absorption are imperative. Herein, Ni-incorporated ZrO 2 /Bi 2 O 3 has been fabricated with p-n heterojunction and a bandgap aligned to absorb visible light up to 560 nm which play an important role in enhancing the production rate of ammonia. The catalyst exhibits a maximum ammonia generation rate of 9668.2 µmol h ?1 g ?1. Further, systematic characterization studies confirm the formation of the desired photocatalyst. This work presents a propitious strategy to configure appropriate visible light responsive photocatalyst that efficiently reduces nitrogen.

The development of two-dimensional (2D) material or heterostructure as an anode material is necessary to enhance the electrochemical performance of Li-ion batteries (LIBs) but finding the correct combination is a challenge. In the present work, using First principles study, we have proposed borophosphene (BP-ML) and graphene-based multilayer heterostructure as a possible anode material. We have found that BP-ML and graphene-based heterostructure are conductive in nature. Here, we have also investigated the role of P z (?) and P y (?) atomic orbital bands of BP-ML and graphene. On Li intercalation, charge transfer is mainly site and interface definitely which helps to improve the specific capacity. The specific capacity of the proposed heterostructure varies from 546 to 427 mA h/g. For maximum Li confirmation, the volume expansion of these heterostructures is about 14–16%. The presence of graphene helps to maintain the open-circuit voltage (OCV) of heterostructure on an average 0.7 V. Also, helps to support the diffusion barrier energy in the range of 0.27–0.71 eV. This proposed 2D heterostructure could be the future material for the LIB's anode material.

The electrocatalytic reduction of CO 2 (CO 2 RR) into value-added hydrocarbons is limited due to high limiting potential (U L ) and competing hydrogen evolution reaction (HER). To find the best catalyst for CO 2 reduction the concept of hydrogen poisoning was not considered in the catalyst screening process. Herein, we present a simple screening method and graphical construction using multiparameter optimization for the design of highly active and selective single-atom catalysts (SAC) using density functional theory calculations. A series of SAC namely, MN4, MBN3 and H@MBN3 (M: metal) are investigated for CO 2 RR. Our results revealed that MN4 and MBN3 SAC are not favorable for CO 2 RR due to high U L  > ?0.85 V and hydrogen poisoning (?G H*  < 0), respectively. H@MBN3 SAC (stable compounds forming H–B bonds) are identified as efficient catalysts with a low value of U L and significantly hinder the competitive HER. Among these, H@CoBN3 and H@FeBN3 SAC show excellent CO 2 RR activity with limiting potential ?0.30 and ?0.44 V respectively for CH 4 production and no chance of HER. Scaling relations reveal the importance of *COOH/*CHO binding energy (E b ) as an energy descriptor to evaluate the catalytic performance. This work provides a new theoretical perspective to design a highly selective catalyst for CO 2 RR.

Tailored metal–organic frameworks with tunable physicochemical properties not only render integration of electroactive species but also facilitate the accessibility of catalytic sites, yet much less discussed for electrocatalysis. Herein, we report a rational shaping of core-shell Zeolitic Imidazolate Frameworks in a scalable seed mediated approach. The Pd encapsulated robust ZIF-8/ZIF-67 nanoarchitectures exhibit highly efficient electrocatalytic oxygen evolution reaction (OER) with low Tafel slope of 85 mV/dec and a 340 mV overpotential. The heterojunction favours a well-matched band energy, efficient charge mobility with exceptional OER with 10 mA cm ?2 anodic current density, high turnover frequency (TOF: 1.21 sec ?1 ), high Faradaic efficiency (91.88 %) and long-term durability as well as stability. The local structure and electrical information of Pd nanoparticles as well as their beneficial cooperative impact on ZIF-8/ZIF-67 affirmed by EXAFS and XANES analyses. Furthermore, DFT studies are harmonious with the experiments, that highly active molecules have a strong synergistic effect for the overall electrocatalytic OER performance exhibited by the catalysts, which elucidate the role of active Pd and Co sites and corroborate the experimental findings.

We describe the design of a flexible solid-state hybrid supercapacitor (FSSHSC) using mixed metal telluride NiLaTe microfibers (MFs) atop Ni foam (NF). The goal of the study is to examine the effect of counter metal ions Ni and La, in addition to Te, in the formation of longer one-dimensional (1-D) architecture. The NiTe MFs and La 2 Te 3 microrods (MRs) were synthesized and compared with bimetallic telluride. La exhibit's slower reaction kinetics than Ni when reacting with Te due to the different crystal structural stability of La 2 Te 3 (cubic phase) and Te (hexagonal phase). Three-electrode investigations incorporating aqueous potassium ferrocyanide (KFC) reveal that the electrochemical performance of NiLaTe MFs is doubled compared to the typical aqueous KOH electrolyte alone. The presence of the redox pair [Fe(CN) 6 ] 3? /[Fe(CN) 6 ] 4? allows for faster ion transport inside the active electrode surface, which improves electrochemical performance. The FSSHSC device was fabricated, comprising NiLaTe as the positive, activated carbon (AC) as the negative electrode, and PVA-KOH-KFC gel, which acts as an electrolyte and a separator. The device performance was compared to that of a liquid system as well as one without a redox additive gel system. The significance of polymer-based gel and KFC for device construction is briefly reviewed. The final built device NiLaTe//AC in gel + KFC system has a maximum areal capacity of 65.6 ?Ah cm ?2 (60.0 mA h g ?1 ) at a current density of 2 mA cm ?2, a maximum energy density of 45.5 Wh Kg ?1 (52.36 ?Wh cm ?2 ), and a maximum power density of 5488.7 W Kg ?1 (6312.0 ?W cm ?2 ). Furthermore, the device outperforms the cyclic stability for 10,000 cycles with an 80.1 % capacity retention and exhibits excellent flexibility at different bending angles. The assembled FSSHSCs device successfully illuminates an LED bulb for 70 s.

Ammonia forms the fundamental agricultural constituent and vital energy provenance of a clean hydrogen mediator. Ammonia production leads to immense energy utilization and drastic environmental repercussion. It is a daunting task to design and synthesize competent catalysts for reduction of nitrogenous species (nitrogen or nitrates, by the nitrogen reduction reaction (NRR) or nitrate reduction reaction (NORR) process, respectively) into ammonia. Cobalt(II) phthalocyanine (CoPc) nanotubes were effectively wrapped by 2D graphene sheets to produce a (1D-2D) heterostructure catalyst, which plays the role of a competent electrocatalyst for the NRR as well as NORR. The electrocatalyst showed an ammonia yield rate and a Faradaic efficiency of 58.82 ?g h mg and 95.12%, respectively, for the NORR and for NRR 143.38 ?g h mg and 43.69%, respectively. Bader charge investigation revealed the transport of charge to Co-N active sites from reduced graphene oxide (RGO), which aids during the production of intermediates NNH* for nitrogen reduction and *NOH for nitrate reduction along with suppression of the parasitic HER, thereby demonstrating good selectivity and Faradaic efficiency. This work showcases new mechanistic discernment about the role of work function, interfacial charge transport, and electrocatalytic overpotential for the nitrogen/nitrate reduction reaction.

The construction of photoactive units in the proximity of a stable framework support is one of the promising strategies for uplifting photocatalysis. In this work, the ultrasmall Pd NPs implanted onto core-shell (CS) metal organic frameworks (MOFs), i.e., CS@Pd nanoarchitectures with tailored electronic and structural properties are reported. The all-in-one heterogeneous catalyst CS@Pd3 improves the surface functionalities and exhibits an outstanding hydrogen evolution reaction (HER) activity rate of 12.7 mmol g h, which is 10-folds higher than the pristine frameworks with an apparent quantum efficiency (AQE) of 9.02%. The bifunctional CS@Pd shows intriguing results when subjected to photocatalytic CO reduction with an impressive rate of 71 ?mol g h of MeOH under visible-light irradiation at ambient conditions. Spectroscopic data reveal efficient charge migrations and an extended lifetime of 2.4 ns, favoring efficient photocatalysis. The microscopic study affirms the formation of well-ordered CS morphology with precise decoration of Pd NPs over the CS networks. The significance of active Pd and Co sites is addressed by congruent charge-transfer kinetics and computational density functional theory calculations of CS@Pd, which validate the experimental findings with their synergistic involvement in improved photocatalytic activity. This present work provides a facile and competent avenue for the systematic construction of MOF-based CS heterostructures with active Pd NPs.

The excess anthropogenic CO depletion via the catalytic approach to produce valuable chemicals is an industrially challenging, demanding, and encouraging strategy for CO fixation. Herein, we demonstrate a selective one-pot strategy for CO fixation into “oxazolidinone” by employing stable porous trimetallic oxide foam (PTOF) as a new catalyst. The PTOF catalyst was synthesized by a solution combustion method using transition metals Cu, Co, and Ni and systematically characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), N sorption, temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS) analysis. Due to the distinctive synthesis method and unique combination of metal oxides and their percentage, the PTOF catalyst displayed highly interconnected porous channels along with uniformly distributed active sites on its surface. Well ahead, the PTOF catalyst was screened for the fixation of CO into oxazolidinone. The screened and optimized reaction parameters revealed that the PTOF catalyst showed highly efficient and selective activity with 100% conversion of aniline along with 96% selectivity and yield toward the oxazolidinone product at mild and solvent-free reaction conditions. The superiority of the catalytic performance could be due to the presence of surface active sites and acid-base cooperative synergistic properties of the mixed metal oxides. A doubly synergistic plausible reaction mechanism was proposed for the oxazolidinone synthesis experimentally with the support of DFT calculations along with bond lengths, bond angles, and binding energies. In addition, stepwise intermediate formations with the free energy profile were also proposed. Also, the PTOF catalyst displayed good tolerance toward substituted aromatic amines and terminal epoxides for the fixation of CO into oxazolidinones. Very interestingly, the PTOF catalyst could be significantly reused for up to 15 consecutive cycles with stable activity and retention in physicochemical properties.

Tellurium (Te) is a metal with the ability to function as a self-sacrificing template and exhibits strong chemical reactivity with counter metals. By the simple inward diffusion of metal ions on its surface, it can form long one-dimensional architect. Utilizing this, a one-dimensional cobalt x nickel (1-x) telluride (Co x Ni (1-x) Te) microfibers (MFs) on nickel foam substrate has been constructed for a bifunctional electrode application. The theoretical and experimental investigations on the Co x Ni (1-x) Te validates the Co 0.75 Ni 0.25 Te superiority over other ratios. The synergistically caused effects at 3:1 Co/Ni ratio reactivity with Te enhance the microstructure bifunctional electrode property with excellent stability during long cycle operation. The density functional theory calculations of Co 0.75 Ni 0.25 Te revealed a better quantum capacitance due to the increased density of states near Fermi levels and achieved the enhanced oxygen evolution reaction activity because of increasing OH coverage. The assembled device Co 0.75 Ni 0.25 Te MF//activated carbon achieves outstanding energy storage performance with a maximum energy density of 50.8 Wh/Kg (58.4 ?Wh/cm 2 ) at a power density of 672.7 W/Kg (773.5 ?W/cm 2 ) and sustains the performance up to 10,000 cycles, with a capacity retention of 90.1%. As an electrocatalyst, Co 0.75 Ni 0.25 Te MF/nickel foam requires a low overpotential ( ? ) of 289 mV to reach a current density ( j ) of 10 mA/cm 2 in 0.1 M KOH for oxygen evolution reaction.

Utilization of bifunctional high-efficiency non-precious electrocatalysts for stable and effective water splitting is crucial to the growth of the clean energy industry. Topologically, the predetermined ordered structures of metal-organic frameworks (MOFs) can be contrived through the judicious assembly of a tailor-made synthesis strategy of layered double hydroxide (LDH) films. Aiming at NiCo-LDH@NH-UiO-66 as a model system, for the first time, we examine the 2-methyl imidazole-induced ultrathin 2D NiCo-LDH nanosheet arrays in NH-UiO-66 as an effective bifunctional electrocatalytic system for overall HO splitting with marvellous performance and robustness in alkaline environments. The progressively tuned NiCo-LDH@NH-UiO-66 catalyst demands overpotential values of 296 and 224 mV to deliver a current density of 50 mA cm for the O evolution reaction (OER) and H evolution reaction (HER) in 1 M KOH aqueous solution, respectively. Tafel studies also revealed favorable reaction kinetics during electrochemical processes. The NiCo-LDH@NH-UiO-66 bifunctional electrode displayed superior activity exhibiting a voltage of 1.65 V at a benchmarking current density of 10 mA cm towards overall water splitting. Importantly, the NiCo-LDH@NH-UiO-66 electrode shows an excellent specific capacitance of 0.00364 mF cm with remarkable durability of the capacitor after 1000 cycles. To compare with the experimental result, we have performed density functional theory (DFT)-based calculation to estimate the HER and OER activity of the NiCo-LDH@NH-UiO-66 heterostructure. From the HER free energy profile and Bader charge analysis, we have confirmed that the presence of NH-UiO-66 helps in H production with 0.10 eV free energy of H adsorption (G). From the OER free energy profile, the estimated overpotential (?) is about 0.96 eV, which confirms that the electrochemical reaction towards the OER is also possible on the NiCo-LDH@NH-UiO-66 structure. This study will bestow a beneficial blueprint for the utilization of an effective, durable, and economical MOF-based bifunctional catalytic system for overall water splitting.

The active sites of electrocatalysts play a crucial role in the material design and mechanistic exploration of an electrocatalytic reaction. Defect-tailored heteroatom-doped carbon-based electrocatalysts for oxygen reduction reaction (ORR) have been much explored, but there is ambiguity in the prediction of active sites responsible for the performance of the material. To find the origin of the activity of this class of catalysts towards ORR, in this work, we use the quantum mechanics/machine learning (QM/ML) approach to derive energy-optimized models with both N-atoms and 5-8-5 defect sites which manifest exemplary ORR activity. Following this approach, we synthesized defect-engineered graphene (DG) using the zinc template method at 1050 °C to achieve optimum N-dopants and intrinsic (5-8-5) defects. The obtained electrocatalyst exhibits hierarchical porosity, high surface area, low nitrogen content, good stability and a satisfying ORR performance with a half-wave potential (E) of 0.82 V, comparable to that of commercial Pt/C (E = 0.82 V). Further, the full energy profile was deduced using density functional theory and the charge redistribution in the material cross-verified a reduced overpotential for ORR. This work provides a strategy for the synthesis of noble-metal-free high-performance electrocatalysts for energy conversion.

Li 3 V 2 (PO 4 ) 3 (LVP) is a well-known cathode material of Li-ion batteries, whereas the specific capacity is limited by the maximum Lithium (Li) de-intercalation probability associated with vacancy energy. The reason behind this limitation is not known yet, which needs to be address, and the modification needs to be done in the electronic structure to get a more specific capacity. In this work, using First-principles calculation, we have found that Li1 (the tetrahedra geometry) is having a higher Li vacancy energy as compared to Li2 and Li3, which limits the Li de-intercalation below x = 1.8, (where x is Li concentration). The change in bandgap of LVP structure after boron (B) substitution is directly correlated to the change in the oxygen (O) occupancy due to B substitution. As of comparing formation energy plot of pristine LVP and B substituted LVBP structure, we have found that in case of LVBP structure formation of x > 2 Li de-intercalation is possible, which help to enhance the specific capacity up to 205 mAh/g. Overall, we identify the cause of the less specific capacity of LVP and provide the solution by suggestion B doping, which also provides less Li diffusion barrier energy.

Ammonia is produced through the energy-intensive Haber-Bosch process, which undergoes catalytic oxidation for the production of commercial nitric acid by the senescent Ostwald process. The two energy-intensive industrial processes demand for process sustainability. Hence, single-step electrocatalysis offers a promising approach toward a more environmentally friendly solution. Herein, we report a 10-electron pathway associated one-step electrochemical dinitrogen oxidation reaction (NOR) to nitric acid by manganese phthalocyanine (MnPc) hollow nano-structures under ambient conditions. The catalyst delivers a nitric acid yield of 513.2 ?mol h g with 33.9% Faradaic efficiency @ 2.1 V versus reversible hydrogen electrode. The excellent NOR performances are achieved due to the specific-selectivity, presence of greater number of exposed active sites, recyclability, and long period stability. The extended X-ray absorption fine structure confirms that Mn atoms are coordinated to the pyrrolic and pyridinic nitrogen via Mn-N coordination. Density functional theory-based theoretical calculations confirm that the Mn-N site of MnPc is the main active center for NOR, which suppresses the oxygen evolution reaction. This work provides a new arena about the successful example of one step nitric acid production utilizing a Mn-N active site-based metal phthalocyanine electrocatalyst by dinitrogen oxidation for the development of a carbon-neutral sustainable society.

The main challenges impeding the widespread use of organic-inorganic lead halide perovskites in modern-day technological devices are their long-term instability and lead contamination. Among other environmentally convivial and sustainable alternatives, CsSnX (X = Cl, Br, and I) compounds have shown promise as ambient-stable, lead-free materials for energy harvesting, and optoelectronic applications. Additionally, they have demonstrated tremendous potential for the fabrication of self-powered nanogenerators in conjunction with piezoelectric polymers like polyvinylidene-fluoride (PVDF). We report on the fabrication of composites constituting solvothermally synthesized CsSnX nanostructures and PVDF. The electroactive phases in PVDF were boosted by the incorporation of CsSnX, leading to enhanced piezoelectricity in the composites. First-principles density functional theory (DFT) studies were carried out to understand the interfacial interaction between the CsSnX and PVDF, which unravels the mechanism of physisorption between the perovskite and PVDF, leading to enhanced piezoresponse. The halide ions in the inorganic CsSnX perovskites were varied systematically, and the piezoelectric behaviors of the respective piezoelectric nanogenerators (PENGs) were investigated. Further, the dielectric properties of these halide perovskite-based hybrids are quantified, and their piezoresponse amplitude, piezoelectric output signals, and charging capacity are also evaluated. Out of the several films fabricated, the optimized CsSnI_PVDF film shows a piezoelectric coefficient (d) value of ?200 pm V and a remanent polarization of ?0.74 ?C cm estimated from piezoresponse force microscopy and polarization hysteresis loop measurement, respectively. The optimized CsSnI_PVDF-based device produced an instantaneous output voltage of ?167 V, a current of ?5.0 ?A, and a power of ?835 ?W across a 5 M? resistor when subjected to periodic vertical compression. The output voltage of this device is used to charge a capacitor with a 10 ?F capacitance up to 2.2 V, which is then used to power some commercial LEDs. In addition to being used as a pressure sensor, the device is employed to monitor human physiological activities. The device demonstrates excellent operational durability over a span of several months in an ambient environment vouching for its exceptional potential in application to mechanical energy harvesting and pressure sensing applications.

The functionalization of nanomaterials offers a significant impact on environmental protection. Three silver composites, silver nanocubes (Ag NCs) with cellulose (Ag-CE), Ag NCs with chitosan (Ag-CH), and Ag NCs with neutral alumina (Ag-NA), were synthesized with the incorporation of a very low concentration of Ag NCs. The synthesized Ag-composites were used for the detection of hazardous analytes, 4-mercaptobenzoic acid (4-MBA), rhodamine 6G (R6G), and methylene blue (MB), via a highly sensitive surface-enhanced Raman scattering (SERS) technique. The enhancement factors for the detection of MB were found to be 1.2 × 10, 1.4 × 10, and 3.7 × 10 using Ag-CE, Ag-CH, and Ag-NA, respectively. Limits of detection of 1 nM, 100 pM, and 100 ?M were achieved for MB using Ag-CE, Ag-CH, and Ag-NA, respectively. The Ag-CH composite achieved excellent sensitivity and enhancement for the detection of MB compared to the other two Ag-composites. The order of detection efficiency of MB using Ag-composites was measured theoretically and follows the order Ag-CH > Ag-CE > Ag-NA. A real-time filtration unit showed excellent efficiency for MB removal. The present method can be employed in commercial filtration processes for the benefit of the environment and sustainable development.

Despite numerous advantages over the traditional light absorbing materials, colloidal cesium lead halide (CsPbX, X = Cl, Br, or I) perovskite nanocrystals (NCs) suffer from enormous defect density, leading to shorter lifetime of charge carriers and material instability. A large number of positively and negatively charged ionic defects are inevitably formed from crystallization via high temperature. Herein, we have studied a simple post-synthesis defect passivation of blue emitting CsPbCl NCs using monovalent metal ion LiCl as a dual-passivating agent. The observed effect (on optical properties) went up by leaps and bounds. Photoluminescence (PL) quantum yield increases from 2.8 to 47.6%, while PL life time increases from 0.56 to 20.79 ns. Various other chloride salts (CaCl, NHCl, KCl, and NaCl) and Li salts (LiBr and LiI) with different cation and anion combinations, respectively, did not give this effect. All these together with the enhanced overall stability of NCs suggest the synergistic effect of dual passivation and deep defect passivation that leads to significant suppression of non-radiative recombination. An X-ray photoelectron spectroscopy study also reveals that this simple strategy promotes simultaneous passivation of both defects (vacancies) formed from negatively (chlorine) and positively charged ions (lead) of CsPbCl Theoretical study and experimental analysis in this work, together delivers a perceptive understanding of cationic and anionic vacancy healing by LiCl in CsPbCl NCs, thus enhancing its utilization as efficient blue light emitters.

Hydrogen as a fuel is a promising alternative to harmful fossil fuels, thereby its production by electrocatalytic hydrogen evolution reaction (HER) is an important research problem. Using density functional theory, H evolution through the Volmer-Tafel (V-T) pathway is studied on borophene sheets. The results reveal that the sheets exhibit high activity, comparable to platinum. A better theoretical understanding of the mechanism that explains the experimental results is an existing issue. To address this issue, we have proposed that H evolves through a bond-exchange mechanism in the Tafel step. The activation energy through this mechanism is drastically reduced, compared to the existing model of direct H evolution and matches well with the experimental results in terms of activation energy for HER. It is also tested and observed on other HER catalysts, such as nitrogen-doped graphene, 2H-MoS, and Pt(111), which proves the proposed mechanism is correct for HER. An electronic property-based descriptor is proposed that shows a good correlation with HER activity on the borophene sheets. This work sheds insights into theoretical modeling of HER and can further lead to better methods toward the understanding of the reaction. Also the electronic descriptor can be tested on similar boron allotropes and reactions.

Ammonia is a crucial biochemical raw material for nitrogen containing fertilizers and a hydrogen energy carrier obtained from renewable energy sources. Electrocatalytic ammonia synthesis is a renewable and less-energy intensive way as compared to the conventional Haber-Bosch process. The electrochemical nitrogen reduction reaction (eNRR) is sluggish, primarily due to the deceleration by slow N diffusion, giving rise to competitive hydrogen evolution reaction (HER). Herein, we have engineered a catalyst to have hydrophobic and aerophilic nature via fluorinated copper phthalocyanine (F-CuPc) grafted with graphene to form a hybrid electrocatalyst, F-CuPc-G. The chemically functionalized fluorine moieties are present in the second coordination sphere, where it forms a three-phase interface. The hydrophobic layer of the catalyst fosters the diffusion of N molecules and the aerophilic characteristic helps N adsorption, which can effectively suppress the HER. The active metal center is present in the primary sphere available for the NRR with a viable amount of H to achieve a substantially high faradaic efficiency (FE) of 49.3% at ?0.3 V vs. RHE. DFT calculations were performed to find out the rate determining step and to explore the full energy pathway. A DFT study indicates that the NRR process follows an alternating pathway, which was further supported by an in situ FTIR study by isolating the intermediates. This work provides insights into designing a catalyst with hydrophobic moieties in the second coordination sphere together with the aerophilic nature of the catalyst that helps to improve the overall FE of the NRR by eliminating the HER.

Eight-electron nitrate reduction (NORR) offers a cost-effective and environmentally friendly route of ammonia production and wastewater remediation. However, identification and reinforcement of the metal-ligand interaction responsible for the catalytic activity in transition-metal phthalocyanine-based heterostructures still remain unclear due to their complexity. Herein, directed by computation, we present a heterostructure approach to couple 2D graphene sheets with 1D manganese (II) phthalocyanine to produce a pyrrolic-N coordinated electron-deficient Mn center that interacts to generate the vital intermediates of the NORR process. The catalyst system delivers an ammonia yield rate of 20,316 ?g h mg, a faradaic efficiency (FE) of 98.3%, and an electrocatalytic stability of 50 h. Mechanistic investigations verified by FTIR spectroscopy and theoretical calculations to identify Mn coordinated pyrrolic-N as the active sites in MnPc and RGO reinforce the active sites by orbital interaction for enhancing the charge transfer in the formation of *NOH @ NORR intermediates while suppressing the competitive hydrogen evolution reaction (HER), resulting in high selectivity and FE.

The oxygen reduction reaction (ORR) is largely influenced by material conductivity as well as electron transfer mobility. Usually, covalent porous polymers are fascinating in terms of the surface area and availability of abundant functionalities serving as active sites. However, this class of materials largely suffers from electronic conductivity issues, which limits their extensive application in electrocatalytic reactions. To overcome this long-standing issue, herein, we have developed a metallo [Fe(ii)]-porphyrin-pyrene based pi-conjugated porous polymer (FePP), which was further modified with electrophoretically exfoliated graphene (FePP@G). The interfacing of these two units via ?-? interaction introduces the flexibility of >C-C< bond rotation resulting in-plane flipping of the bridging -Ph ring from out of plane orientation. The ring flipping-induced co-planarity was investigated through experimental and computational studies. In situ FTIR and operando Raman studies reveal that the ORR process with the FePP@G catalyst follows a 4e reduction pathway. This phenomenon drives axial as well as equatorial charge mobility within the system influencing the active FeN site toward lowering the overpotential for the ORR.

This work showcases a novel strategy for the synthesis of shape-dependent alloy nanostructures with the incorporation of solid substrates, leading to remarkable enhancements in the electrocatalytic performance. Herein, an aqueous medium approach has been used to synthesize an octahedral PdCu alloy of different Pd:Cu ratios to better comprehend their electrocatalytic potential. With the aim to outperform high activity and efficient stability, zirconium oxide (ZrO), graphene oxide nanosheets (GONs), and hexagonal boron nitride nanosheets (hBNNs) solid substrates are occupied to decorate the optimized PdCu catalyst with a minimum 5 wt % metal loading. When compared to the counterparts and different ratios, the PdCu@hBNNs catalyst exhibited an optimal activity for hydrogen evolution reaction (HER). The lower overpotential and Tafel values observed are 64 and 51 mV/dec for PdCu@hBNNs followed by PdCu@ZrO, which showed a 171 mV overpotential and a 98 mV/dec Tafel value, respectively. Meanwhile, the PdCu@GONs were found to have a 202 mV overpotential and a 110 mV/dec Tafel value. The density functional theory, which achieves a lower free energy (?G) value for PdCu@hBNNs than the other catalysts for HER, further supports its excellent performance in achieving the Volmer-Heyrovsky mechanism path. Moreover, the superior HER activity and sturdier resilience after 8 h of stability may be due to the synergy between the metal atoms, monodisperse decoration, and the coordination effect of the support material.

Defect engineering through modification of their surface linkage is found to be an effective pathway to escalate the solar energy conversion efficiency of metal-organic frameworks (MOFs). Herein, defect engineering using controlled decarboxylation on the NH-UiO-66 surface and integration of ultrathin NiCo-LDH nanosheets synergizes the hydrogen evolution reaction (HER) under a broad visible light regime. Diversified analytical methods including positron annihilation lifetime spectroscopy were employed to investigate the role of Zr-rich defects by analyzing the annihilation characteristics of positrons in NH-UiO-66, which provides a deep insight into the effects of structural defects on the electronic properties. The progressively tuned photophysical properties of the NiCo-LDH@NH-UiO-66-D-heterostructured nanocatalyst led to an impressive rate of HER (?2458 ?mol h g), with an apparent quantum yield of ?6.02%. The ultrathin NiCo-LDH nanosheet structure was found to be highly favored toward electrostatic self-assembly in the heterostructure for efficient charge separation. Coordination of Zr on the surface of the NiCo-LDH nanosheet support through NH-UiO-66 was confirmed by X-ray absorption spectroscopy and electron paramagnetic resonance spectroscopy techniques. Femtosecond transient absorption spectroscopy studies unveiled a photoexcited charge migration process from MOF to NiCo-LDH which favorably occurred on a picosecond time scale to boost the catalytic activity of the composite system. Furthermore, the experimental finding and HER activity are validated by density functional theory studies and evaluation of the free energy pathway which reveals the strong hydrogen binding over the surface and infers the anchoring effect of the ultrathin layered double hydroxide (LDH) in the vicinity of the Zr cluster with a strong host-guest interaction. This work provided a novel insight into efficient photocatalysis via defect engineering at the linker modulation in MOFs.

Using first-principles calculations, we investigate a family of doped graphene nanoribbons (GNRs) for their suitability as cathode hosts in lithium-sulfur batteries. We probe the role played by the lone pairs of the dopants in confining the lithium polysulfides (LiPS) to understand the mechanism of binding. Our results show that the Li bond between the polysulfides and the doped GNRs is analogous to a hydrogen bond and also dipole-dipole interactions play a key role in anchoring the polysulfides. A critical donor-Li-acceptor angle of 180° is found to be essential for proper adsorption of LiPS, highlighting the importance of the directionality of lone pairs. The charge lost by the sulfur atom of the polysulfide upon adsorption and shape of the lone pair basins and the value of Electron Localization Function (ELF) at the dopant position can provide a quick estimate of the strength of the bond. Significant contractions in the ELF profiles are also observed upon LiS adsorption, further providing evidence for the hydrogen bond-like nature of the Li bond. Our results corroborate the fact that all acceptors capable of forming hydrogen bonds can be employed as suitable dopants for carbon-based cathode hosts in Li-S batteries.

In borophene, vacancy is a major reason for stability. However, a detailed understanding relating to vacancy and electronic property remains unexplored. Using Density Functional Theory (DFT) the effect of vacancy and doping on stability, electronic and catalytic properties of borophene is addressed in this work. It is shown how vacancy increases ?-electrons and decreases ?-electrons of the neighboring boron atoms with the magnitude decreasing from 4 to 6-coordinated atoms, thereby contributing to their stability. The role of single and dual carbon doping on ?- and ?-occupancy is explored. In addition, we have shown that dual carbon doping on ? 12 -borophene analogue reduces the overpotential for oxygen evolution reaction (OER). We observed that the charge deficient boron atom helps in the reduction of oxygen binding and can decrease the overpotential towards OER. Overall, this work would help in fundamental understanding towards borophene stability and aid in choosing the suitable dopant for catalytic applications considering the stability.

Selective epoxidation of olefins is a very important reaction as epoxides are widely been used as platform chemical in polymer and pharmaceutical industries. Unlike conventional oxidants like molecular O 2 or peroxides, the use of CO 2 as a soft oxidant for the oxidation of olefins is very challenging as it offers the utilization of waste and plentiful CO 2 together with the potential for the mitigation of its harmful environmental effect. Thus, this process is cost effective and environmentally challenging. Herein, we report the synthesis of a new crystalline porous organosilica material TSOS-1 with orthorhombic crystal structure by using a tailor made bridging organoslilane precursor prepared through the Schiff base condensation of p -terphenyl-4,4?'-dialdehyde and 3-aminopropyl-trimethoxysilane. This novel crystalline material TSOS-1 has been synthesized hydrothermally in the absence of any structure-directing agent and it showed high BET surface area (220 m 2 g ?1 ) and nanoscale porosity. TSOS-1 is used as a support for stabilizing tiny AgNPs to obtain a robust nanocatalyst Ag@TSOS-1, which efficiently catalyses the conversion of styrene into predominantly styrene oxide (SO) using CO 2 as a soft oxidant in an autoclave reactor under mild reaction conditions.

Tuning the electronic structure of perovskite oxides via aliovalent substitution is a promising strategy to attain inexpensive and efficient electrocatalysts for energy conversion and storage devices. Herein, following the d-band center positions and using a simple sol-gel method followed by a pyrolysis step, LaNi1-xCo0.5xFe0.5xO3 (LNFCO-x; x = 0.0, 0.4, 0.5, and 0.6) electrocatalysts are designed and synthesized for oxygen redox reactions in 1 M KOH. Among them, LNFCO-0.5 has exhibited the lowest overpotential and the highest charge transfer kinetics in oxygen redox reactions. Overall, a 90 mV lower overpotential was observed in oxygen redox activity of LNFCO-0.5 compared to that of pristine LaNiO3. The mass activity of LNFCO-0.5 in the oxygen reduction reaction (at 0.7 V vs RHE) and oxygen evolution reaction (1.60 V vs RHE) was calculated to be 2.5 and 2.13 times higher than that of LaNiO3, respectively. The bifunctionality index (potential difference between the oxygen evolution at a current density of 10 mA cm-2 and the oxygen reduction at a current density of -1 mA cm-2) of LNFCO-0.5 was found to be 0.98. The substitution of Fe and Co for the Ni-site shifted the d-band center close to the Fermi level, which can increase the binding strength of the *OH intermediate in the rate-determining step. Also, the surface was enriched with Fe3+?, Co3+, and partially oxidized Ni3+ states, which is susceptible to tune the eg-orbital filling for superior oxygen redox activity.

Trirutile NiTaO has been studied under high pressure by in situ Raman and angle-dispersive synchrotron X-ray diffraction techniques. It undergoes a new quenchable phase at high pressures above 11.8 GPa accompanied by softening of the internal modes ?(A), ?(E), and ?(E), and it is denser by 15% compared with its ambient phase. Various Raman-active modes of NiTaO diminished at high pressures due to the distortion of edge-sharing TaO octahedra, which was further confirmed by X-ray diffraction and density functional theory results. The equation of state has been determined using the second-order Birch-Murnaghan equation, and the obtained bulk modulus is 199(4) GPa. The pressure and volume dependence of optical lattice vibrational frequencies and their corresponding Grüneisen parameters are calculated, indicating the inconsistency of the trirutile structure at high pressures, which was accompanied by the strong deformation of TaO octahedra. Pressure-induced structural metamorphosis and soft-mode-driven displacive transition related to the mechanical instability of NiTaO are examined and decompression results recommend the transition is irreversible.

The design and development of new and light weight two-dimensional (2D) heterostructures as anode materials to enhance the electrochemical properties for Li-ion batteries (LIB’s) is a challenge. In this work, using first-principles study, we have demonstrated that the ratio of two-dimensional polyaniline (C 3 N) and graphene in the multilayer heterostructures plays a major role to define the Li storage properties and to provide metallicity for easy conduction of electrons. We have found that charge transfer between Li and the host depends on the interface and site, which helps in the improvement in specific capacity. The proposed heterostructures shows specific capacity varies from 558 mAh/gm to 423 mAh/gm. The specific capacity is high for heterostructures with more graphene in ratio which is correlated to higher charge accumulation in the host. Also, graphene helps to minimize the open-circuit voltage (OCV) of C 3 N and maintained an average of 0.4 V. The volume expansion for fully lithiated heterostructures is within 22 %. Li diffusion barrier energy varies in the range of 0.57 to 0.25 eV. The proposed 2D heterostructures could be a future material for anode in LIB’s and the description of the interface effect on Li storage properties will help for further development of 2D heterostructure materials.

To cease the ever-increasing energy demand, additional enthusiastic focus has been given to generate more sustainable energy from alternative renewable sources. Storage of these energies for future usage solely banks on energy storage devices. A diversity of electrode materials based on two-dimensional (2D) transition metals and their derivatives have enticed the whole world owing to their tunable properties. Transition metal trichalcogenides (MX3 type) are the emergent class of 2D materials, which gathered a lot of interest because of their quasi-one-dimensional anisotropic properties with the van der Waals force of attraction in between the layers. Herein, TiS3 being a MX3-type of material is preferred as the battery type-supercapacitor electrode for energy storage applications with detailed theoretical predications and experimental validations. The highest capacitance attained for TiS3 is found to be 235 F/g (105 C/g) at 5 mV/s with a battery type of charge storage mechanism. The asymmetric hybrid device is fabricated using Ti3C2Tx MXene nanosheets as a negative electrode, and a brilliant 91% of capacitance retention is accomplished with an extensive potential window of 1.5 V. The investigational discoveries are substantiated by theoretical simulation in terms of the quantum capacitance assessment and charge storage mechanisms.

Particulate matter (PM) in air frequently poses a serious threat to human health. Smaller PM can easily enter into the alveolus and blood vessels with airflow. This work reports the first polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) polymer blend nanofiber filter media for effectively capturing PM. Density functional theory (DFT) calculations are used to investigate the effect of the blending of two polymers on the dipole moment and the electrostatic potential. Based on the DFT calculations of the intermolecular interactions between nanofibers and PM, the PAN/ PVP heteromolecular percentage is considered for experimental synthesis, which can provide better performance in the filtration of pollutants. The composite PAN/PVP fiber network was successfully developed and optimized to cope with complex environments during the actual filtration process. The role of the blending ratio of PAN and PVP in wt % was explored on PM capture, and the refined ratio overcame the conflict between high filtration efficiency and low air pressure resistance. The air filter medium PAN/PVP (6:2) possesses an extremely high air filtration efficiency of 92% under a very low pressure drop of 18 Pa for a 0.5 g m basis weight. Both polar and nonpolar functional groups in blend nanofibers promoted significantly the electrostatic attraction and improved the filtration efficiency under static and dynamic airflow. The PAN/PVP nanofiber membranes maintain outstanding air filtration under different temperature and humidity conditions. This study will shed light on the fabrication of high-efficiency low-basis weight nanofiber filter media as an end product.

An effective modulation of the active sites in a bifunctional electrocatalyst is essentially desired, and it is a challenge to outperform the state-of-the-art catalysts toward oxygen electrocatalysis. Herein, we report the development of a bifunctional electrocatalyst having target-specific Fe-N/C and Co-N/C isolated active sites, exhibiting a symbiotic effect on overall oxygen electrocatalysis performances. The dualism of N-dopants and binary metals lower the d-band centers of both Fe and Co in the Fe,Co,N-C catalyst, improving the overpotential of the overall electrocatalytic processes (?E = 0.74 ± 0.02 V vs RHE). Finally, the Fe,Co,N-C showed a high areal power density of 198.4 mW cm and 158 mW cm in the respective liquid and solid-state Zn-air batteries (ZABs), demonstrating suitable candidature of the active material as air cathode material in ZABs.

The exclusive characteristic properties of two-dimensional (2D) materials have enticed most of the researchers and scientific community to employ a plethora of pioneering stratagems in order to puzzle out modern-day problems. Some of the possibilities are currently are at theoretical phases, while some of them are well-explored experimentally. Nanoribbon-like structures of the 2D materials are ancillary entrants for 2D nanosheets with tunable and enhanced properties. Protuberant properties like abundant and highly exposed active sites on the edges facilitated electron transfer, and superior charge mobility, etc. make them poles apart from their bulk counterparts. Nowadays, these nanoribbon-like structures are contributing to countless applications such as solar cells, photodetectors, sensing, field emission, energy storage, and catalysis. Accordingly, we have put an overview of recent advancements in the properties, preparations, and applications of nanoribbon-like structures based on 2D materials. The contemporary review thoroughly recapitulates the numerous properties of nanoribbon-like materials including crystal structure, bandgap, optical, electrical, magnetic, and catalytic properties. Moreover, the review also addresses the tuning approaches used to optimize the properties of nanoribbon materials. The most recent synthesis approaches used for the preparation of nanoribbon-like structures are also highlighted along with their exceptional implementation in various intriguing applications. Furthermore, this comprehensive review put the finishing touches on a discussion of the present-day outlook and some of the crucial scientific challenges which have to be addressed to improve the performances of nanoribbons of 2D materials-based devices.

Green synthesis of urea under ambient conditions by electrochemical co-reduction of N and CO gases using effective electrocatalyst essentially pushes the conventional two steps (N + H = NH and NH + CO = CO(NH)) industrial process at high temperature and high pressure, to the brink. The single step electrochemical green urea synthesis process has hit a roadblock due to the lack of efficient and economically viable electrocatalyst with multiple active sites for dual reduction of N and CO gas molecules to urea. Herein, copper phthalocyanine nanotubes (CuPc NTs) having multiple active sites (such as metal center, Pyrrolic-N3, Pyrrolic-N2, and Pyridinic-N1) as an efficient electrocatalyst which exhibits urea yield of 143.47 µg hmg and faradaic efficiency of 12.99% at –0.6 V versus reversible hydrogen electrode by co-reduction of N and CO are reported. Theoretical calculation suggests that Pyridinic-N1 and Cu centers are responsible to form CN bonds for urea by co-reduction of N to NN* and CO to *CO, respectively. This study provides the new mechanistic insight about the successful electro-reduction of dual gases (N and CO) in a single molecule as well as rational design of efficient noble metal-free electrocatalyst for the synthesis of green urea.

Concerns have grown in recent years about the widespread use of the pesticide thiram (TRM), which has been linked to negative effects on local ecosystems. This highlights the critical need for quick and accurate point-of-need pesticide analysis tools for real-time applications. The detection of TRM using gold nanorods (Au NRs) with a limit of detection of 10M (10 pM) and an enhancement factor of 2.8 × 10along with 6.2% of signal homogeneity (with respect to the peak at 1378 cm) is achieved through surface-enhanced Raman scattering (SERS). The formation of an Au-S bond emphasizes the adsorption of TRM on Au NRs. The addition of Au NRs to TRM of higher and lower concentrations yields a side-by-side assembly (SSA) and a bridging facet assembly (BFA), respectively, and exhibited excellent hotspots for the ultralow detection of TRM. Bridging facets of Au NRs, such as (5 12 0) and (5 0 12) planes, are mainly responsible for the BFA. This kind of interaction is observed for the first time and not reported elsewhere. The detailed facets of Au NRs, namely, side facets, bridging facets, and pyramid facets were demonstrated with the 3D model of Au NRs. The computational studies confirming the SSA and BFA for Au NRs with varying concentrations of TRM are in well agreement with the experimental results. The interaction of Au NRs with TRM is highly sensitive, and the ultralow detection of hazardous TRM through SERS is an ideal technique for environmental protection, real-time applications, and analysis of one-of-a-kind materials.

The hydrogen-bonded organic frameworks (HOFs) have gained significant attention due to their various alluring applications in the fascinating field of supramolecular chemistry. Herein, we report the electrocatalytic activity of HOFs toward the hydrogen evolution reaction (HER) by utilizing the molecular adduct of cyanuric and trithiocyanuric acid with various organic substrates (melamine and 4,4?-bipyridine). Both the experimental and theoretical findings provide insights and validate the electrocatalytic activity toward HER applications. This work contributes significantly to designing novel highly efficient metal-free HOF-based electrocatalysts for the HER.

The orthorhombic nanostructured NdNiO3 is prepared by the sol-gel auto-combustion method, and its temperature-dependent magnetic and electrical transport properties are studied. The electric field emission with density functional theory and current voltage characteristics are also investigated at room temperature. The low-temperature magnetic measurement (magnetization with field and temperature) shows that NdNiO3 undergoes a magnetic phase transition (TN) near 176 K from paramagnetic to spin-canted antiferromagnetic state. The temperature-dependent magnetic susceptibility (?) reinforced the signature of magnetic phase transition, and it is fitted by the modified Curie-Weiss law. A metal to insulator (MIT) phase transition (?178 K) is observed above TN from temperature- and frequency-dependent conductivity measurement. It originates due to higher distortion of NiO6 octahedra and bandwidth constriction of NdNiO3 nanostructured compound. The variation of the frequency exponent (n) with temperature illustrates the continuous-time random walk conduction model with bipolaron condensation near MIT and the non-overlapping small polaron tunneling model above room temperature. The spin-resolved density of states calculation exhibits the room temperature paramagnetic phase and metallic nature and helps us to calculate local work function (?) ?5.44 eV. Low turn-on field at 1 ?A/cm2 ?10.5 V/?m and high field emission current density 203 ?A/cm2 at 21 V/?m are observed for layered NdNiO3 with a field enhancement factor (?) ?1230, which promotes NdNiO3 as an efficient field emitter. The current-voltage characteristics of NdNiO3/p-Si heterostructures are also explored for future technological applications.

The growing demands for ammonia in agriculture and transportation fuel stimulate researchers to develop sustainable electrochemical methods to synthesize ammonia ambiently, to get past the energy-intensive Haber-Bosch process. However, the conventionally used aqueous electrolytes limit N solubility, leading to insufficient reactant molecules in the vicinity of the catalyst during electrochemical nitrogen reduction reaction (NRR). This hampers the yield and production rate of ammonia, irrespective of how efficient the catalyst is. Herein, we introduce an aqueous electrolyte (NaBF), which not only acts as an N-carrier in the medium but also works as a full-fledged “co-catalyst” along with our active material MnN to deliver a high yield of NH (328.59 ?g h mg) at 0.0 V versus reversible hydrogen electrode. BF-induced charge polarization shifts the metal d-band center of the MnN unit close to the Fermi level, inviting N adsorption facilely. The Lewis acidity of the free BF molecules further propagates their importance in polarizing the N?N bond of the adsorbed N and its first protonation. This push-pull kind of electronic interaction has been confirmed from the change in d-band center values of the MnN site as well as charge density distribution over our active model units, which turned out to be effective enough to lower the energy barrier of the potential determining steps of NRR. Consequently, a high production rate of NH (2.45 × 10 mol s cm) was achieved, approaching the industrial scale where the source of NH was thoroughly studied and confirmed to be chiefly from the electrochemical reduction of the purged N gas.

The diverse coordination environment on the surface of carbon-based nanomaterials contributes significantly to their unique adsorption properties. Here, we perform first-principles calculations to determine the sensitivity and selectivity of pristine, 1B, and homonuclear 2B-doped graphdiyne, pentagraphene, and phagraphene structures toward toxic phosgene (COCl) gas molecule. The strength of the phosgene gas adsorption on the perfect surfaces is negligible, while the substitution of homonuclear boron on the studied substrates can make inert carbon allotropes into an active material for capturing the COClgas molecule. Further, the charge density difference and Lowdin charge analysis were computed to provide additional insights for understanding the phenomenon clearly, and the results are completely consistent with the observed trends. The prominent changes in the electronic structure of homonuclear boron-doped surfaces indicate strong reactivity toward phosgene gas molecules, thereby inducing significant variations in the conductivity or resistivity of the sensing device. The ?electron occupancy is correlated with the sensing of carbon materials toward phosgene. Overall, homonuclear 2B-doped graphidyne and 1B/2B-doped pentagraphene display high selectivity and sensitivity with better performance, which makes them potential candidates toward target phosgene gas molecules. These fundamental atomic-scale insights may furnish novel outcomes into the rational design of defect engineered carbon-based nanomaterials for the detection of toxic phosgene gas molecules.

As a promising candidate for low-cost and eco-friendly thin-film photovoltaics, the emerging quaternary chalcogenide based solar cells have experienced rapid advances over the past decade. Here, we propose quaternary semiconducting chalcogenides CuZn2AlSe4 (CZASe) through cross-substitutions (cation mutations). The nonexistence of imaginary modes in the entire Brillouin zone of CZASe represents the inherent dynamic stability of the system. The electronic, optical, and defect properties of stannite CZASe quaternary semiconducting material was systematically investigated using density functional theory calculations. We have found that the chemical-potential control is very important for growing good-quality crystals and also to avoid secondary-phase formations such as ZnSe, Al2ZnSe4, and Cu3Se2. The observed p-type conductivity is mainly due to antisite defect CuZn, which has the lowest formation energy with a relatively deeper acceptor level than that of the Cu vacant site (VCu). The electronic band structures of vacancies and antisite defects by means of hybrid functional calculations show energy band shifting and energy band narrowing or broadening, which eventually tunes the optical band gap and improves the solar energy-conversion performance of semiconducting CZASe. Our results suggest that the stannite CZASe quaternary chalcogenides could be promising candidates for the efficient earth-abundant thin-film solar cells.

With the emergence of wearable and portable electronics, solid-state supercapacitors are considered as a promising candidate to power electronic devices because of their interesting features compared to existing energy storage devices. Polyaniline is a promising candidate for energy storage and conversion applications due to its high theoretical capacitance and intrinsic conductivity. Still, relatively sluggish rate capability and energy storage performance should be addressed to compete with existing high-performance electrode materials. Here, we fabricated a solid-state supercapacitor electrode with an organic-inorganic hybrids of polyaniline (PANI) and black phosphorus (BP) to overcome the sluggish electrochemical performance. The fabricated supercapacitor device provides an exceptional specific capacitance of 350 mF cm (116 F g) at a current density of 0.4 mA cm and displays a high energy density of 31.1 ?W h cm at a power density of 330 mW cm along with good cycling stability of 83.3% after 10 000 charge-discharge cycles. Also, this material shows a decent electrocatalytic HER performance with an overpotential value of 128 mV at a current density of 10 mA cm, a Tafel slope of 71 mV dec, and outstanding stability up to 24 h. Finally, DFT studies confirmed that the PANI/BP hybrid is a more promising electrode material for supercapacitor applications with higher C due to a larger density of states near the Fermi level as compared to pristine BP and PANI.

The electrochemical nitrogen reduction reaction (eNRR) offers the possibility of ammonia synthesis under mild conditions; however, it suffers from low yields, a competing hydrogen evolution reaction pathway, and hydrogen poisoning. We present a systematic approach toward screening single atom catalysts (SACs) for the eNRR, by focusing on key parameters computed from density functional theory and relationships between them. We illustrate this by application to 66 model catalysts of the types, TM-Pc, TM-NC, and TM-N, where TM is a 3d transition metal or molybdenum. We identified the best SACs as Sc-Pc, Cr-N, Mn-Pc, and Fe-NC; these show eNRR selectivity over the HER and no hydrogen poisoning. The catalysts are identified through multi-parameter optimization which includes the condition of hydrogen poisoning. We propose a new electronic descriptor O, the valence electron occupancy of the metal center that exhibits a volcano-type relationship with eNRR overpotential. Our multi-parameter optimization approach can be mapped onto a simple graphical construction to find the best catalyst for the eNRR over the HER and hydrogen poisoning.

The use of tetracycline (TC) for the treatment of infectious diseases caused by bacteria has been humongous over the past few decades. However, the presence of untreated TC in freshwater leads to antimicrobial resistance. To prevent this concern from damaging the freshwater system, a stable sensor with high selectivity and rapid detection towards TC is desirable. Metal-Organic Frameworks (MOFs) are organic-inorganic hybrid structures with excellent stability, multifunctional ability, and tuneable pore structure that find extensive applications in detection techniques. The structural adaptability, excellent porosity and large surface area of MOFs prove advantageous in terms of adsorption of antibiotics. With this insight, a highly stable Zn-based Luminescent Metal-Organic Framework (LMOF) for the selective detection of tetracycline was developed. It is worth mentioning that, the LMOF-based sensor showed no depreciation in luminescence activity and can be reused more than 10 times. Moreover, a very low detection limit of 0.11 ?M and a Stern-Volmer quenching constant (K sv ) value of 1.16 × 10 4  M ?1 indicate its sensitivity precision towards TC detection. A significant inner filter effect of TC was observed in addition to adsorption of TC on the MOF through hydrogen bonding. Further, test strips based on IRMOF-3 showed satisfactory recovery in real-time samples. Thus, the stimuli-responsive sensor reports a simple strategy for excellent sensing performance towards TC.

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Two dimensional material based heterostructures have been widely investigated for high performance energy storage applications due to their distinctive advantages. These heterostructures remove most of the congenital shortcomings belonging to each individual structure. In this study, electrochemical energy storage performance of the chromium diselenide (CrSe)/TiC MXene heterostructure is examined. CrSe is a lesser explored layered TMD and is a promising candidate for energy storage applications. MXene on the other hand is an emerging material and is being extensively studied for its unique intrinsic energy storage abilities. The CrSe/TiC MXene heterostructure electrode displays an enhanced energy storage performance in a basic electrolyte medium. The multi-dimensional hierarchical architecture of CrSe/TiC MXene results in an increased number of active sites for electrochemical activities and improves the electrochemical stability. The synergistic interplayed effect triggered by fast ionic/electronic transportation, reduced agglomeration and volume expansion, etc. can be accounted for the enhanced electrochemical performance of the heterostructure. An all-solid-state supercapacitor is fabricated to utilize and demonstrate the energy storage capability of CrSe/TiC MXene in real time applications. The fabricated device showed a compelling performance during the electrochemical assessment.

Visible light-mediated photoredox catalysis has emerged to be a fascinating approach for the activation of CO2 and its subsequent fixation into valuable chemicals utilizing renewable and inexhaustible solar energy. Although great progress has been made in CO2 photoreduction, visible light-assisted organic synthesis using CO2 as a reactive substrate is rarely explored. Herein, we report an efficient, facile, and economically viable photoredox-mediated approach for the synthesis of important ?-thioacids via carboxylation of olefins with CO2 and thiols over a porous functionalized metal-organic framework (MOF), Fe-MIL-101-NH2, as a photocatalyst under ambient conditions. This multicomponent reaction offers wide substrate scope, mild reaction conditions, easy work-up, cost-effective and reusable photocatalysts, and higher product selectivity. Computational studies suggested that CO2 interacts with the thiophenol-styrene adduct to facilitate the synthesis of ?-thioacids in almost quantitative yields.

Ammonia has been recognized as the future renewable energy fuel because of its wide-ranging applications in H storage and transportation sector. In order to avoid the environmentally hazardous Haber–Bosch process, recently, the third-generation ambient ammonia synthesis has drawn phenomenal attention and thus tremendous efforts are devoted to developing efficient electrocatalysts that would circumvent the bottlenecks of the electrochemical nitrogen reduction reaction (NRR) like competitive hydrogen evolution reaction, poor selectivity of N on catalyst surface. Herein, we report the synthesis of an oxygen-functionalized boron carbonitride matrix via a two-step pyrolysis technique. The conductive BNCO architecture, the compatibility of B-2p orbital with the N-2p orbital and the charging effect over B due to the C and O edge-atoms in a pentagon altogether facilitate N adsorption on the B edge-active sites. The optimum electrolyte acidity with 0.1 M HCl and the lowered anion crowding effect aid the protonation steps of NRR via an associative alternating pathway, which gives a sufficiently high yield of ammonia (211.5 ?g h mg) on the optimized BNCO catalyst with a Faradaic efficiency of 34.7% at ? 0.1 V vs RHE. This work thus offers a cost-effective electrode material and provides a contemporary idea about reinforcing the charging effect over the secured active sites for NRR by selectively choosing the electrolyte anions and functionalizing the active edges of the BNCO catalyst.[Figure : see fulltext.].

Layered two-dimensional (2D) materials demonstrate exceptional performance as supercapacitor electrodes due to their unique intrinsic properties. A hybrid 2D/2D heterostructured electrode material can synergize the individual energy storage features of each of the layered 2D materials. TiC MXene is an emergent 2D material with enriched energy storage capabilities but suffers from certain vulnerabilities during the charge storage process. Vanadium ditelluride (VTe) is an interesting yet unexplored layered material within the 2D transition metal dichalcogenide (TMD) family. Owing to the unique structural features, VTe showcases certain advantages in energy storage. The formation of the VTe/TiC MXene heterostructure for energy storage applications has not been reported until now. Herein, we report a facile and simple hydrothermal synthesis approach to prepare bare VTe and the VTe/MXene heterostructure for supercapacitor applications. The energy storage mechanism in the heterostructure is systematically analyzed. The synergistically induced interplaying effects enhance the specific capacitance of the heterostructure to 250 F g along with excellent durability during long cycle operation. Consequently, an asymmetric system is constructed with VTe/MXene as the positive electrode and MoS/MXene as the negative electrode. The 2D/2D heterostructure-based asymmetric supercapacitor delivers excellent performance with an energy density of 46.3 W h kg and a highest power density of 6400 W kg. Furthermore, the density functional theory calculations predict that the enhancement of electronic Te 5P states near the Fermi level due to MXene leads to improved performance of the VTe/TiC hybrid for supercapacitor applications.

Conjugated polymers and titanium-based metal-organic framework (Ti-MOF) photocatalysts have demonstrated promising features for visible-light-driven hydrogen production. We report herein a strategy of anisotropic phenanthroline-based ruthenium polymers (PPDARs) over Ti-MOF, a tunable platform for efficient visible-light-driven photocatalytic hydrogen evolution reaction (HER). Several analytical methods including X-ray absorption spectroscopy (XAS) revealed the judicious integration of the surface-active polymer over the Ti-MOF reinforcing the catalytic activity over the broad chemical space. PPDAR-4 polyacrylate achitecture led to a substantial increase in the H evolution rate of 2438 µmolgh (AQY: 5.33%) compared to pristine Ti-MOF (238 µmol g h). The separation of photogenerated charge carriers at the PPDAR-4/Ti-MOF interface was confirmed by the optical and electrochemical investigations. The experimental, as well as theoretical data, revealed their physical and chemical properties which are positively correlated with the H generation rate. This offers a new avenue in creating polymer-based MOF robust photocatalysts for sustainable energy.

The composition of two different categories of anode materials, i.e. layered and alloy type is the future of anode material in Li-ion batteries. In our work, using First-principles approach, we proposed multilayer heterostructure of graphene/graphite (layered type) with silicon monolayer (Si-ML) (origin is alloy type), as a potential anode material for LiB’s. The synergetic effect of the delocalized ? electron of carbon and localized ? electron of Si-ML plays a crucial role in maintaining the electron and ion conductivity increases the stability and specific capacity with moderate open circuit voltage. The model structures proposed in this work shows high specific capacities in the range of 748 to 438 mAh-gm ?1. This indicates that we can tune the specific capacity using the different ratio of carbon and silicon layers. The localized ? electron helps to restrict the volume expansion within 15% for a fully lithiated model structure. The low interlayer diffusion energy of Li-ion makes all the heterostructure as a potential anode material. The proposed study will help to understand the Li storage properties of the carbon/silicon based composite to develop the anode materials with a certain approach.

A novel route to fabricate Cu 2 O/CuO heterojunction electrodes using an atmospheric pressure plasma jet (APPJ) is demonstrated. This process promotes favourable band alignment and produces nanoscale CuO surface features from Cu 2 O with low density of interfacial defects. This electrode can operate without any transparent current collector, showing remarkable currents and stability towards oxygen evolution reaction (OER) (6 mA cm ?2 for 2 h at pH14) as well as photocatalytic hydrogen evolution reaction (HER) activity (?1.9 mA cm ?2 for 800 s at pH7). When the electrocatalytic oxygen evolution (OER) activity was measured for Cu 2 O/CuO electrode deposited on FTO substrate the currents increased to ~40 mA cm ?2 at 0.8 V vs SCE in 1 M KOH without compensating for the electrode electrolyte surface resistance ( iR correction). The composite films also exhibited a high rate towards photo degradation of Methylene Blue (MB) and phenol in the visible spectra, indicating efficient charge separation. We modelled the electronic structure of this epitaxially grown Cu 2 O/CuO heterojunction using density functional theory. The calculations revealed the distinctive shifts towards Fermi level of the p -band centre of O atom in Cu 2 O and d -band centre of Cu atom in CuO at the interface contribute towards the increased catalytic activity of the heterostructure. Another factor influencing the activity stems from the high density of excited species in the plasma introducing polar radicals at the electrode surface increasing the electrolyte coverage. This work presents the potential of APPJ functionalization to tune the surface electronic properties of copper oxide based catalysts for enhanced efficiency in OER and HER water splitting.

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Descriptor based model can be efficient in identifying an optimal carbon-based catalyst for oxygen evolution reaction (OER). Here, we correlate the O-atom adsorption strength with the OER activity of graphene nanoribbon systems and define the energy parameters (?G O -?G OH ) to identify the overpotential (?). The ? electron based descriptor can predict the catalytic activity of the graphene surfaces. Machine learning algorithms like Multiple Linear Regression, Random Forest Regression and Support Vector Regression (SVR) are trained on the data generated by density functional theory to predict the overpotential. An optimal active site for OER using proposed SVR model is identified with overpotential (0.29 V) and then validate through DFT calculations. To generalize the study, we used SVR model on N doped GNR to predict the site-specific activity towards OER. Such a combined approach can be extended to estimate the site-specific OER activity of different carbon catalysts at a dramatically reduced computational cost.

A novel memory capacitor structure has been presented with AlO/AlO bilayer dielectrics on high mobility Epitaxial-GaAs substrate. We have demonstrated the chemical and electrical properties of metal–electrode/AlO/AlO/epi-GaAs-based memory device in detail. Sputter-grown non-stoichiometric AlO has been used for both the charge trapping layer and blocking layer due to its intrinsic charge trapping capability and high bandgap. Ultra-thin tunneling layer of thicknesses 5 nm and 15 nm were prepared by atomic layer deposition technique and memory properties were compared on promising high mobility Epitaxial-GaAs/Ge heterostructure. The proposed device shows excellent charge trapping properties with a maximum memory window of 3.2 V at sweep voltage of ± 5 V, with good endurance and data retention properties. Oxygen-deficient AlO layer acted as a charge trapping layer without any additional blocking layer which is impressive for non-volatile memory application on high mobility epi-GaAs substrate. In addition, density Functional Theory (DFT) has been employed to understand the physical origin of the intrinsic charge trapping defects in AlO dielectric layer.

Ambient particulate matter air pollution has become a serious environmental issue and poses grave threats to public health globally. The indoor and outdoor air protection could be achieved by filtering devices and facial masks. The development of air filter to eliminate particulate matter pollution from the air is necessary for human safety. To realize this, here a class of nanofiber air filter is reported with high efficiency and very low pressure drop. By controlling the surface chemistry through cetyltrimethylammonium bromide, it is achieved a >99.9% removal efficiency under extreme hazardous air-quality conditions for PM2.5 with quality factor of 0.469 Pa-1 and low ?11 Pa pressure drop. The dipole moment and intermolecular interaction between the nanofibers and PM2.5 are investigated by density functional theory calculations. A long-term 15 day filtration test has proven that the nanofiber air filter maintains an excellent efficiency of 99%. This work pushes forward a significant step toward the design and development of high efficiency and a very low pressure drop air filter for various applications.

The development of low-cost molecular electrocatalysts for the ER from water remains scarce. The efficient electrocatalytic hydrogen volution reactions (HER) with a series of sterically encumbered carbene igated silver(I), gold(I) and nickel(II) complexes established here demonstrate he potential of molecular catalyst in hydrogen production from water. Tuning he benzannulation on the coumarin-substituted N-heterocyclic carbene (NHC) ligands afforded six new silver(I) (5-10), two new gold(I) (11 and 2), and two reported nickel(II) (13 and 14) NHC complexes, which differ by he steric bulk around the metal atom and the counterion. Benefiting from the esirable structure and appropriate porous morphology, complexes 6, 9, 10, and 11 exhibited significant electrocatalytic HER activity in acidic medium with n overpotential of-226.4,-445,-243 and-310 mV vs RHE, respectively, to rive a current density of 10 mA/cm2 when immobilized on glassy carbon lectrode, which is analogous to that of several transition metal-based anomaterials. The kinetic parameters such as Tafel slope value and exchange current density for the active complexes and the ormer observation authenticated the Volmer-Heyrovsky mechanism. Theoretical studies advocate the potential of developing novel eries of carbene-ligated HER electrocatalysts based on the controlled ligand field following scalable and viable protocols.

Electrocatalytic ammonia (NH3) synthesis through the nitrogen reduction reaction (NRR) under ambient conditions presents a promising alternative to the famous century-old Haber-Bosch process. Designing and developing a high-performance electrocatalyst is a compelling necessity for electrochemical NRR. Specific transition metal based nanostructured catalysts are potential candidates for this purpose owing to their attributes such as higher actives sites, specificity as well as selectivity and electron transfer, etc. However, due to the lack of a well-organized morphology, lower activity, selectivity, and stability of the electrocatalysts make them ineffective at producing a high NH3 yield rate and Faradaic efficiency (FE) for further development. In this work, stable ?-cobalt phthalocyanine (CoPc) nanotubes (NTs) have been synthesized by a scalable solvothermal method for electrochemical NRR. The chemically synthesized CoPc NTs show excellent electrochemical NRR due to high specific area, greater number of exposed active sites, and specific selectivity of the catalyst. As a result, CoPc NTs produced a higher NH3 yield of 107.9 ?g h-1 mg-1cat and FE of 27.7% in 0.1 M HCl at -0.3 V vs RHE. The density functional theory calculations confirm that the Co center in CoPc is the main active site responsible for electrochemical NRR. This work demonstrates the development of hollow nanostructured electrocatalysts in large scale for N2 fixation to NH3.

Support-catalyst interface plays a critical role in electrocatalytic processes as the rates of involved reactions are directly linked with the interfacial charge transfer efficiency. Here, we are presenting nitrogen doped exfoliated graphite foil (NGF) as the 3D support which offers electronically coupled interface to catalytic heterostructure comprises of nickel-iron based oxide and its borate. As developed hybrid (NGF/NiFe/Borate) show excellent oxygen evolution reaction (OER) under alkaline condition with low overpotential of 281?mV at current density of 10?mA?cm ?2 and Tafel slope 62?mv?dec ?1. The results beat most nonprecious metal catalysts and noble commercial IrO 2 deposited over same NGF substrate with outstanding long-term durability over 10?h at high current density 300?mA?cm ?2. Efficient electron injection from NGF support and its low resistance leads to enhancement in current density by more than 136 % at operative potential of 1.55?V, in comparison to un-doped exfoliated graphite foil support. Beside electronically tuned support, high catalytic efficiency is also linked with planner growth of borate nanosheets that helps in fast interfacial charge transfer in its transverse direction to the catalytic site. Our work highlights the importance of electronic tuning of catalyst support to enhance the performance of supported borate catalyst and to rationally design low cost, highly active OER catalyst.

To enhance the catalytic efficiency of graphene quantum dot (GQD) for ORR, the role of S-dopant and S-linker is explored here by utilizing the first-principles density functional theory-based approach. The ORR efficiency is found to be changed on different active sites with the variation of dopant position and dopant configuration on the sulfurized GQD. Charge transfer from the dopant site to the active sites and to the intermediates, as well as the binding energy of intermediates on the active sites play an important role to realize the potential determining step, onset potential and the overpotential for ORR. The increase in the doping concentration of S or the presence of oxygen is found to drastically enhance the ORR efficiency of GQD. Furthermore, S-linkers are exploited to connect two GQDs entangled or twisted with each other and resulting in a rather complex system. The combined effect of entangling, S-linkers and presence of a single N dopant at the meta position of the active site resulted in the adsorption of the intermediates with optimum binding strength. Consequently, the ORR activity is found to be enhanced, thereby resulting in a metal-free and cost-effective electrocatalyst with efficiency similar to the Pt-based metal catalysts.

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The burst of energy produced from the sustainable energy sources need to be harnessed by energy storage systems. Development of novel and advanced energy storage devices such as supercapacitors discover an enormous future ahead. Recently, hybrid supercapacitors (electric double layer capacitor (EDLC) and pseudocapacitors) trend to be used as energy storage interfaces for their improved efficacy in energy density without altering the power density. In the ongoing workplan, transition metal selenides MnSe 2 and its hybrid with multiwalled carbon nanotubes (MWCNTs) are synthesized by a simplistic hydrothermal protocol. Certainly, cubic phases of MnSe 2 -MWCNT(MS/CNT) manifested superior electrochemical performance in both symmetric and asymmetric full cell configurations in contrast to prestine MnSe 2 (MS). The asymmetric MS/CNT cell achieved an excellent charge storage capability with an high energy density of 39.45 Wh kg ?1 at a power density of 2.25 kW kg ?1 maintaining an energy density of 14.5 Wh kg ?1 at a high power density of 4.5 kWh kg ?1 and also revealed long term stability over 5000 consecutive charge/discharge cycles (capacitance retention of 95.2%). Furthermore, the preferable growth along (2 0 0) direction in the presence of MWCNTs favoured in enriching the supercapacitive property of MS. The quantum capacitance of MnSe 2 surfaces and MS/CNT heterostructure has been estimated using density functional theory simulation to confirm the experimental outcomes. Theoretical investigation simultaneously exposed the contribution of (2 0 0) plane of MnSe 2 and MWCNTs cultured in enhanced DOS (density of states) near the Fermi level that remarkably promoted the energy storage efficiency of MS/CNT.

Graphitic carbon nitride (g-C 3 N 4 ), a 2D-organic semiconductor, has rapidly emerged as a potential alternative to the 2D-inorganic semiconductors in photocatalysis, but rare studies have been made hitherto about its applicability in optoelectronic devices. Considering the specific requirements of light-emitting diodes with efficient recombination of injected-carriers and photodetector devices with better charge separation, this work deals with synthesizing two variants of g-C 3 N 4 samples with exclusively modified optical/electronic properties while keeping its basic structural framework. One sample is two-coordinated nitrogen deficient g-C 3 N 4 (Nd-gCN) having very high photoluminescence (PL) and the other is hydrogen substituted g-C 3 N 4 (H-gCN) exhibiting vanishingly low PL and ?0.66 eV smaller bandgap than Nd-gCN. Role of nitrogen-vacancy and hydrogen substitution towards modulating optical/electronic properties of g-C 3 N 4 are studied by combining experiments and density functional theory. Following strong luminescence, Nd-gCN sample manifests visibly blue emission in light-emitting devices; contrarily H-gCN sample shows potential in demonstrating efficient broadband photodetection. Besides moderate self-powered feature, photodetectors perform best at –5.0 V, corresponding to the highest responsivity R?=0.34A/W, EQE?=59% and response time (0.18/0.29 sec). Efficient broadband photodetection performance of the heterojunction-devices is ascribed to the conjunct effects of drastic reduction in photogenerated carrier recombinations (PL quenching) and broadening of absorption regime facilitated by reduced bandgap and Si self-absorption.

Development of an inexpensive electrocatalyst for hydrogen evolution (HER) and oxygen evolution reactions (OER) receives much traction recently. Herein, we report a facile one-pot ethyleneglycol (EG) mediated solvothermal synthesis of orthorhombic Co 2 P with particle size ~20–30 nm as an efficient HER and OER catalysts. Synthesis parameters like various solvents, temperatures, precursors ratios, and reaction time influences the formation of phase pure Co 2 P. Investigation of Co 2 P as an electrocatalyst for HER in acidic (0.5 M H 2 SO 4 ) and alkaline medium (1.0 M KOH), furnishes low overpotential of 178 mV and 190 mV, respectively to achieve a 10 mA cm ?2 current density with a long term stability and durability. As an OER catalyst in 1.0 M KOH, Co 2 P shows an overpotential of 364 mV at 10 mA cm ?2 current density. Investigation of Co 2 P NP by XPS analysis after OER stability test under alkaline medium confirms the formation of amorphous cobalt oxyhydroxide (CoOOH) as an intermediate during OER process.

Electrochemical ammonia synthesis by the nitrogen reduction reaction (NRR) using an economically efficient electrocatalyst can provide a substitute for the Haber-Bosch process. However, identification of active sites responsible for the origin of catalytic activity in transition metal phthalocyanine is a difficult task due to its complex structure. Herein, density functional theory (DFT) is applied to identify the probable active sites of nickel phthalocyanine (NiPc) for the NRR as well as the origin of catalytic activity which is associated with the d band center and density of states (DOS) of Ni in NiPc. Accordingly, NiPc nanorods (NRs), synthesized by a solvothermal method in large scale, exhibit an NHyield rate about 85 ?g hmgand a faradaic efficiency (FE) of 25% at ?0.3 Vvs.RHE. Moreover, the catalyst shows long term stability up to 30 hours while maintaining the NHyield and FE. The isotopic labelling experiment and other control investigation led to validation of the nitrogen source in NHformation. This study provides brand new insightful understanding of the active sites and the origin of the catalytic activity of NiPc for their NRR applications.

We garnered three important factors simultaneously, namely, wormhole mesoporosity of TiOwith well-designed interfaces for effective charge transfers, precise loading of MoSfor plasmon induction, and increased surface area with exposed surface atoms and active sites. The controlled loading of MoSon porous TiO(MPT) forms a heterojunction that effectively modulates the interface engineering and thereby greatly enhances hydrogen evolution. The synthesis of a photocatalyst is based on a simple hydrothermal process that is well characterized. The resulting composite materials were tested for hydrogen evolution reactions. At optimum loading, MPTinduced a maximum hydrogen evolution rate of 1376 ?mol hgwith 2.28% apparent quantum yield (AQY), which was 10-fold higher compared to the MCT(MoS-commercial TiO) Hevolution rate of 138 ?mol hgwith 0.23% AQY under similar reaction conditions. The shorter decay component, lower emission intensity, and higher estimated lifetime of MPTsuggest its superiority over other materials. Density functional theory (DFT) calculations have further revealed the active sites of MPT and hierarchical porous TiO(HPT) to support the experimental hydrogen evolution reaction (HER). This study suggests an avenue to design an efficient noble-metal-free photocatalyst for solar fuel productions.

We report a cost-effective electro-catalyst for oxygen reduction reaction (ORR) by developing a composite between graphene oxide and carbon nanotubes and simultaneously doping with a nitrogen atom. The nitrogen-doped carbon nanotube/graphene oxide composites were prepared by chemical oxidation method followed by annealing process. Such composite enhances the active adsorption sites, electrical conductivity and corrosion resistance leading to better impact toward ORR. The N-graphene oxide/functionalized carbon nanotube catalyst that furnishes both pyridinic-N and pyridinic-N-O (or oxidic-N) shows higher efficiency toward electrocatalytic ORR performance in alkaline conditions. More interestingly, as-prepared electrocatalyst shows durability test up to 20 000 potential cycles without loss in its half-wave potential (E) while commercial Pt/C catalyst shows a huge loss in E value under similar conditions, indicating sustainability in the performance of former, especially compared to the reported metal or metal-free electrocatalysts. The origin of high catalytic activity of oxidic-N is correlated with ?-electron density at the Fermi level studied by density functional theory and considered as an electronic descriptor.

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1T Molybdenum disulfide (1T-MoS 2 ) has been widely studied experimentally as an electrode for supercapacitors due to its excellent electrical and electrochemical properties. Whereas the capacitance value in MoS 2 is limited due to the lower density of electrons near the Fermi level, and unable to fulfill the demand of industry i.e. quantum capacitance preferably higher than 300 ?F/cm 2. Here, we investigated the performance of 2H, 1T, and 1T? phases of MoS 2 in its pristine form and heterostructures with carbon-based structures as an electrode in the supercapacitors using density functional theory. Specifically, we reported that the underneath carbon nanotube (CNT) is responsible for the structural phase transition from 1T to 1T? phase of MoS 2 monolayer in 1T?-MoS 2 /CNT heterostructure. This is the main reason for a large density of states near Fermi level of 1T?-MoS 2 /CNT that exhibits high quantum capacitance (C Q ) of 500 ?F/cm 2 at a potential of 0.6 V. Also, we observed that the nitrogen doping and defects in the underneath carbon surface amplify the C Q of heterostructure for a wider range of electrode potential. Therefore, the 1T?-MoS 2 /N doped CNT can be explored as an electrode for next-generation supercapacitors.

Hydrogen evolution reaction (HER) by electrochemical water splitting is one of the most active areas of energy research, yet the benchmark electrocatalysts used for this reaction are based on expensive noble metals. This is a major bottleneck for their large-scale operation. Thus, development of efficient metal-free electrocatalysts is of paramount importance for sustainable and economical production of the renewable fuel hydrogen by water splitting. Covalent organic frameworks (COFs) show much promise for this application by virtue of their architectural stability, nanoporosity, abundant active sites located periodically throughout the framework, and high electronic conductivity due to extended ?-delocalization. This study concerns a new COF material, C-TRZ-TFP, which is synthesized by solvothermal polycondensation of 2-hydroxybenzene-1,3,5-tricarbaldehyde (TFP) and 4,4?,4??-(1,3,5-triazine-2,4,6-triyl)tris[(1,1?-biphenyl)-4-amine]. C-TRZ-TFP displayed excellent HER activity in electrochemical water splitting, with a very low overpotential of 200 mV and specific activity of 0.2831 mA cm together with high retention of catalytic activity after a long duration of electrocatalysis in 0.5 m aqueous HSO. Density functional theory calculations suggest that the electron-deficient carbon sites near the ? electron-donating nitrogen atoms are more active towards HER than those near the electron-withdrawing nitrogen and oxygen atoms.

We employed a facile approach to synthesize a ‘two dimensional/three dimensional (2D/3D)’ heterostructure of hexagonal boron nitride and reduced graphite oxide (h-BN/rGO). Interestingly, 2 wt% h-BN loaded heterostructure (i.e. BN/rGO-2) exhibits a superior capacitive performance, including specific capacitance (C sp ) of 304 and 226 F g ?1 at 1 A g ?1 in alkaline and acidic conditions respectively with an excellent rate capability (~98% retention @10k cycles). Importantly, the electrochemical analysis confirms the accumulation of charge solely on the surface/near-surface reactions (capacitive contribution) and not due to the diffusion-limited processes. The solid-state symmetric supercapacitor cell exhibits specific energy of 1.25 Wh kg ?1 corresponding to the high power density of 1800 W kg ?1. The enhancement in the C sp is mainly attributed to the non-hierarchical assembly of a 2D/3D heterostructure, which provides a special interface to the electroactive species. Furthermore, the mechanically activated GO (A-GO) plays a crucial role by enhancing the specific surface area and mesoporosity, thus establishing a positive synergistic effect on capacitive properties, upon composite formation with h-BN. Our theoretical assessment shows that the surface functionalities of GO, as well as h-BN, help to enhance the quantum capacitance of graphene-related materials.

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Van der Waals (VDW) interaction-based heterostructures are known for enhanced photon absorption. However, the origin of these phenomena is not yet completely understood. In this work, using first-principles calculations, we provide a comprehensive study to show the effect of vdW interactions on the optical and electrical characteristics of the device and its origin. Herein, MoS/2D (where 2D varies as graphene, black and blue phosphorene, and InSe) vdW heterojunctions are considered as model structures. The change in the band gap of the heterostructures is because of hybridisation and the non-linearity of the exchange-correlation functional. Hybridisation is correlated with strain and the difference in interstitial potential between layers of the heterostructure and the vacuum level. Significantly, the estimated values of energy conversion efficiency are high in the case of MoS/InSe and MoS/BlackP vdW heterostructures as compared to MoS/GR and MoS/BlueP, suggesting their potential application in efficient and atomically thick excitonic solar cell devices.

Electric field emission (FE) properties are measured on self-assembled NiCrO nanosheets in a planner “diode” arrangement at a base pressure of ?1.0 × 10 mbar. The turn-on field at FE current density 1 ?A cm and the threshold field at FE current density 10 ?A cm are observed as 4.10 and 4.94 V ?m, respectively. The local work function (?) is calculated as 4.358 eV, using density functional theory (DFT) in Quantum Espresso code and field enhancement factor (?) intensified up to 2074 from the sharp edges of the NiCrO nanosheet arrays’ emitter surface. An exemplary FE current stability is observed from the current–time plot over a period of 4.5 h. The field enhancement factor (?), inferior turn-on field, and superior stability compared with any other pristine nanosheet compound recommend its potential application in flat panel display and vacuum micro-/nanoelectronics.

Microstructural NiO-SnO nano-ceramic matrix was synthesized via a solgel auto-combustion technique with a perspective to investigate its noteworthy electric field emission and temperature-induced conduction anomaly. Exceptional field emission performance of nickel-tin oxide composites was discovered with a low turn-on field of 3.9 V/?m and a threshold field of 5.30 V/?m with a good field emission current density of 110.44 ?A/cm and current stability. Density functional theory was employed to estimate its local work function (?) 3.365 eV, and the field enhancement factor (?) was obtained as 1570 by Fowler-Nordheim plot. The anomalies in conductivity spectra at 523 K were detected by a number of physical properties measurement including impedance, conductivity, dielectric, and differential scanning calorimetry with thermal expansion. These phenomena can be rationalized in terms strain-dependent thermal hysteresis effects and localized/delocalized e g electron with a transition from inferior conductive linkage [Ni-O-Ni] and [Sn/Sn-O-Sn/Sn] to higher conductive linkage [Ni-Ni] and [Sn-Sn] of coupled NiO-SnO matrix. The temperature dependence frequency exponent (n), ln ?, R, R, C, and C support additionally the conduction anomaly behavior, and the variation of dielectric constant (?) and loss (tan ?) with temperature around 523 K has been explained in terms of the reduction of space charge layers due to reversal movement of delocalized e g electrons from the grain boundary limit. The frequency dispersing impedance, conductivity, and dielectric spectra with elevated temperature were also demonstrated to comprehend its conduction mechanism with theoretical correlation.

The cornerstone of the emerging hydrogen economy is hydrogen production by water electrolysis with concomitant oxygen generation. Incorporating a third element in metal phosphides can tune the crystalline and electronic structure, hence improving the electrocatalytic properties. In this work, Mn-doped NiP with varying ratios of Mn and Ni has been explored as excellent catalysts for water splitting. A complete cell made of the best catalyst NiMnP electrodes showed low voltage of 1.75 V at a current density of 10 mA cm due to enhanced electrical conductivity, induction of tensile stress, enhanced electrochemical surface area, and increased electric dipole upon Mn incorporation.

BiFeO 3 -based composite materials are important due to their versatile multiferroic properties which can be further tuned upon doping. 0.5BiNd x Fe 1-x O 3 -0.5PbZrO 3 (x?=?0.05, 0.1, and 0.2) polycrystalline ceramic samples were prepared by solid-state reaction technique at high temperature. X-ray diffraction (XRD) and Rietveld refinement process confirm the presence of mainly rhombohedral ( R 3 c ) phase. Dielectric studies reveal the presence of Maxwell-Wagner type polarization. Electric impedance and modulus values of the samples were studied over a wide range of temperature and frequency. Complex impedance and modulus studies shows the presence of non-Debye type of relaxation in the materials. ac conductivity results can be fitted with Jonscher's power law and indicates the dominance of correlated barrier hopping mechanism in charge transport. Furthermore, density of states calculated from ac conductivity shows variation as a function of dopant content which is further corroborated from density functional theory-based results.

The electric field-induced sterling electron emission of NiMnO microporous networks synthesized via the sol-gel auto combustion route was investigated. Some primary characterization techniques such as x-ray diffraction, Fourier-transform infrared spectroscopy, and Raman spectroscopy were performed to confirm the pure crystallinity and metal oxide (Ni-O and Cr-O) stretching vibrations and also to provide a molecular fingerprint of the NiMnO porous network. The distinct field emission (FE) properties of the NiMnO microporous network was observed which was correlated with an electric field induced electron tunneling F-N (Fowler-Nordheim) model from a nearly planner conducting emitter surface with triangular potential-energy barrier approximation. A low turn-on field of 4.15 V µm and threshold field of 5.25 V µm were detected to draw emission current densities of 1 µA cm and 10 µA cm respectively. The local work function (?) of 5.509 eV for the NiMnO porous network was computed using density functional theory (DFT) and it exhibits an impressive field enhancement factor (?) of 3381 with good FE current stability. These results demonstrate the potential application of this material for future vacuum micro/nanoelectronics and FE panel display applications.

A hierarchical NiO-[CdO] 2 nanocomposite has been synthesized by a sol–gel auto-combustion route and characterized with a view to studying the electric field emission and conduction mechanism therein. The structural features, surface morphologies, and elemental compositions of the as-prepared samples have been characterized by XRD, Raman, FESEM, and TEM techniques. A low turn-on field (4.50 V/?m) and threshold field (5.04 V/?m) were found to be sufficient to draw emission current densities of 1 ?A/cm 2 and 10 ?A/cm 2 from NiO-[CdO] 2 -modified cathodes. A maximum emission current density of 121 ?A/cm 2 at a low applied electric field of 6.5 V/?m and long emission current stability were achieved at a preset value of 5 ?A. The field enhancement factor (?) was determined as 1854 in the high-field region by computing the local work function (?) through density functional theory (DFT), and the entire field emission (FE) performances have been compared with those of various pristine compounds. The temperature-dependent electrical conduction mechanism has been further explained with the help of impedance analysis over the temperature range 323–623 K and a wide frequency range from 5 Hz to 1 MHz. The grain and grain boundary contributions were well distinguished by impedance and a modulus formalism, with respective activation energies of E g  = 0.25–0.26 eV and E gb  = 0.31–0.32 eV. The temperature-dependent frequency exponents for grains (n 1 ) and grain boundaries (n 2 ) demonstrate two different conduction mechanisms, namely quantum mechanical tunneling for grains, and correlated barrier hopping for grain boundaries. Maxwell–Wagner-type dielectric polarizations are explained by our experimental results, and the highest real dielectric constant (? r ) 1893 was calculated at 623 K.

A fundamental understanding of the spillover mechanism is an open and challenging problem and plays an important role in catalysis. In particular, bond-exchange spillover mechanism is considered to be effective for reversible storage and release of hydrogen at near ambient conditions. For this, three critical steps are needed: finding the right support (acceptor), the right catalyst to split H 2, and ensuring that once H 2 is split, the H atoms can migrate on the surface with the help of secondary catalysts and eventually hydrogenate the entire material. In this paper we address these challenges using density functional theory. We show that BH 3, a secondary catalyst, can be produced by symmetrically splitting its stable precursor, B 2 H 6, on doped metal-free surfaces such as graphene and h-BN as well as on MOF5. In addition, to reduce computational cost, we develop structural descriptor and predictive model equation to effectively screen potential BH 3 binding sites. Symmetrical splitting of B 2 H 6 on different types of materials can address the hydrogen spillover challenge, making efficient storage of hydrogen possible.

This article presents the experimental and theoretical insights into defect-engineered MoO2 nanostructures (NSs) in terms of oxygen vacancy and OH- occupancy toward oxygen evolution reaction (OER). Two categories of ?-MoO2 NSs are grown on a silicon substrate via a hydrogenation process from pregrown ?-MoO3 structures. The postgrown MoO2 system gets OH- occupancy after 7 h of annealing (MoO2+OH-). On increasing the annealing duration to 9 hrs, both oxygen vacancies and OH- occupancy have been made into the MoO2 system (MoO2-x+OH-). The as-grown materials have been assessed for promising energy conversion applications toward electrocatalytic OER. The as-grown MoO2-x+OH- very efficiently catalyzes the OER at a lower overpotential and yields a higher current density compared to the as-grown MoO2+OH- and commercial MoO2. Both the oxygen vacancy and OH- occupancy in the MoO2 system play a synergistic role in enhancing the OER properties. The experimental observations are validated theoretically and plausibly explained with the help of a state-of-the-art density functional study. The simulation calculations reveal that the introduction of oxygen vacancy and OH- occupancy lowers the overpotential of OER. The OH- ions act passively on the surfaces of MoO2 that decrease the binding of reaction intermediates and aid in easy desorption of O2 molecules. Besides, the oxygen defect sites reduce the charge-transfer resistance, which eventually reduces the OER overpotential. Our empirical findings with theoretical supports render a significant shrewdness to the electrocatalytic performances of the defect-engineering MoO2 systems toward OER applications.

The design of stable, highly active heterogeneous nanocatalyst with no CO poisoning is a challenge for the catalytic converter industry. This can be achieved by defining electronic descriptor and by understanding the bonding mechanism. We present results using density functional theory to design optimal metal nanoalloy catalysts for CO oxidation. The adsorption configuration of O 2 and O on different active sites is studied in detail to find the efficient reaction pathway for CO oxidation. The varying extent of back-donation of charge is found to be the factor deciding the CO tolerance. The trade-off between the activity and CO tolerance signifies that there is an upper limit for alloying Pt with Ni and Co. An electronic descriptor based on the occupancy of the d orbital and d band center of the host atom is defined to explain the site dependent activity of nanocatalysts. The role of underneath carbon surface on the CO oxidation activity of metal sites and CO poisoning is described.

Presence of curvature is considered as a tuning parameter to activate the hydrogen storage capability of carbon nanostructures. Here, we explicate the role of ‘intra-curvature’ in a set of single-walled carbon nanohorns (SWCNHs), to adsorb light metal ad-atoms (M) e.g. Li, Na, Ca and subsequently explore the metal-doped systems for hydrogen storage application using density functional theory. The binding strength of ad-atoms on SWCNHs of different curvature is correlated with the ? electron occupancy of the corresponding carbon ring. Higher ? electron occupancy causes significantly high binding energy of the metal ad-atoms (M), thereby indicating high stability of those M?C bonds for intra-curvature values more than 11?, even at a higher temperature. After full hydrogenation, Li-doped SWCNHs are found to contain a maximum of 7.5 wt % of hydrogen. Overall, our results indicate that Li-doped SWCNHs with intra-curvature values higher than 11?, is a potential candidate for hydrogen storage.

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A generalized method for sorting nanoparticles based on their cores does not exist; it is an immediate necessity, and an approach incorporating cost-effectiveness and biocompatibility is in demand. Therefore, an efficient method for the separation of various mixed core-compositions or dissimilar metallic nanoparticles to their pure forms at the nano-bio interface was developed. Various simple core-combinations of monodispersed nanoparticles with dual cores, including silver plus gold, iron oxide plus gold and platinum plus gold, to the complex three-set core-combinations of platinum plus gold plus silver and platinum plus iron plus gold were sorted using step-gradient centrifugation in a sucrose suspension. Viscosity mediated differential terminal velocities of the nanoparticles permitted diversified dragging at different gradients allowing separation. Stability, purity and properties of the nanoparticles during separation were evaluated based on visual confirmation and by employing advanced instrumentations. Moreover, theoretical studies validated our experimental observations, revealing the roles of various parameters, such as the viscosity of sucrose, the density of the particles and the velocity and duration of centrifugation, involved during the separation process. This remarkably rapid, cost-efficient and sustainable strategy can be adapted to separate other cores of nanoparticles for various biomedical research purposes, primarily to understand nanoparticle induced toxicity and particle fate and transformations in natural biotic environments.

The earth abundant and non-toxic solar absorber material kesterite CuZnSn(S/Se) has been studied to achieve high power conversion efficiency beyond various limitations, such as secondary phases, antisite defects, band gap adjustment and microstructure. To alleviate these hurdles, we employed screening based approach to find suitable cationic dopant that can promote the current density and the theoretical maximum upper limit of the energy conversion efficiency (P(%)) of CZTS/Se solar devices. For this task, the hybrid functional (Heyd, Scuseria and Ernzerhof, HSE06) were used to study the electronic and optical properties of cation (Al, Sb, Ga, Ba) doped CZTS/Se. Our in-depth investigation reveals that the Sb atom is suitable dopant of CZTS/CZTSe and also it has comparable bulk modulus as of pure material. The optical absorption coefficient of Sb doped CZTS/Se is considerably larger than the pure materials because of easy formation of visible range exciton due to the presence of defect state below the Fermi level, which leads to an increase in the current density and P(%). Our results demonstrate that the lower formation energy, preferable energy gap and excellent optical absorption of the Sb doped CZTS/Se make it potential component for relatively high efficient solar cells.

Anode materials that exhibit high energy density, high power density, long life cycle, and better safety profile for lithium-ion batteries are necessary for the development of electric vehicles. Computational and experimental studies to describe the relevant aspects of carbon allotropes as anode materials are discussed, toward the significant improvement of specific power and energy capacity. The role of types of carbon ring and mixed hybridization (sp, sp, and sp) in carbon-based anode materials for Li storage explored. An overview is provided on the procedures used to analyze the storage properties of anode materials using first-principles theoretical methods such as intercalation energy, volume expansion, and open circuit voltage. Finally, the progress, importance, design, and the challenges of carbon-based anode materials are comprehensively discussed.