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Electrocatalytic activities for the oxygen reduction reaction (ORR) of Au electrodes modified by as prepared and size selected (0.45–1.0, 0.22–0.45, and 0.1–0.22 µm) h-BN nanosheet (BNNS), which is an insulator, were examined in O2 saturated 0.5M H2SO4 solution. The overpotential was reduced by all the BNNS modifications, and the smaller the size, the smaller the overpotential for ORR, i.e., the larger the ORR activity, in this size range. The overpotential was reduced by as much as ∼330 mV compared to a bare Au electrode by modifying the Au surface by the BNNS of the smallest size range (0.1–0.22 µm). The overpotential at this electrode was only 80 mV more than that at the Pt electrode. Both the rotation disk electrode experiments with Koutecky–Levich analysis and rotating ring disk electrode measurements showed that more than 80% of oxygen is reduced to water via the four-electron process at this electrode. These results strongly suggest and theoretical density functional theory calculations support that the ORR active sites are located at the edges of BNNS islands adsorbed on Au(111). The decrease in size of BNNS islands results in an effective increase in the number of the catalytically active sites and, hence, in the increase in the catalytic activity of the BNNS/Au(111) system for ORR. [ABSTRACT FROM AUTHOR]

In the realm of sustainable and environmentally friendly "green-hydrogen" fuel demand, water electrolysis stands as a pathway of hope for the extraction of renewable hydrogen. However, the durability and efficiency of electrocatalysts have been a major challenge in this process, owing to factors like the high costs of noble catalysts (Pt, Ir, Ru, etc.) and their limited stability. Layered Nickel-iron double hydroxides (NiFe-LDH) have shown potential as low-cost and efficient electrocatalysts because of their suitable electronic configuration and distinguished orbital confinement. However, their durability In the realm of sustainable and environmentally friendly "green-hydrogen" fuel demand, water electrolysis stands as a pathway of hope for the extraction of renewable hydrogen. However, the durability and efficiency of electrocatalysts have been a major challenge in this process, owing to factors like the high costs of noble catalysts (Pt, Ir, Ru, etc.) and their limited stability. Layered Nickel-iron double hydroxides (NiFe-LDH) have shown potential as low-cost and efficient electrocatalysts because of their suitable electronic configuration and distinguished orbital confinement. However, their performance and durability in corrosive alkaline water at high current density remain limited. In this regard, one can make the nano-composites of this NiFe-LDH with high electronic conductivity materials and layered structures like VSe 2. With this motivation, this work presents a novel electrocatalyst, NiFe-LDH, supported with VSe 2 nanosheets ( V Se 2 / NiFe − LDH), designed to address these challenges and enhance water splitting efficiency. Experimental results demonstrate that the heterostructure synergistically reduces charge transfer resistance, increases exposure of active sites, and enhances oxygen gas evolution ability. Consequently, the V Se 2 / NiFe − LDH electrocatalyst demonstrated superior sustainability, maintaining an elevated current density (500 mA cm − 2 ) for over 50 h of continuous electrolysis without noticeable degradation. This research opens up new possibilities and shows that nano-compositing can be a good option for achieving efficient and durable electrocatalysts in alkaline water splitting, thereby contributing to sustainable hydrogen production. [Display omitted] • Facile hydro/solvothermal preparation of composites of NiFe-LDH and VSe 2. • Enhanced Oxygen and Hydrogen evolution were observed. • Decreased charge transfer resistance was noticed. • Durable up to about 50 h for overall water splitting at a high current density of 500 mA cm − 2. [ABSTRACT FROM AUTHOR]

We demonstrate the key role played by the structural transformation of MOF cocatalyst on BiVO 4 photoanode in PEC water splitting. Owing to the significantly reduced overpotential and enhanced hole extraction, the highest photocurrent density of 4.0 mA/cm2 at 1.23 V RHE have been obtained. [Display omitted] • A facile electrochemical activation method was developed to transform CoZn-MOFs to CoOOH on BiVO 4 photoanode. • CoOOH cocatalyst with rich active sites could significantly enhance the hole extraction and reduce the OER overpotential. • The highest photocurrent density of 4.0 mA/cm2 at 1.23 V RHE have been obtained in this work. • This work provides a new insight in understanding the key role of the structural transformation of MOF cocatalyst. Photoelectrochemical (PEC) water splitting has been widely investigated for solar-to-hydrogen conversion. However, issues like high charge recombination rate and slow surface water oxidation kinetics severely hinder its (PEC) conversion efficiency. Herein, we constructed MOF-derived CoOOH cocatalyst on BiVO 4 photoanode, using a feasible electrochemical activation strategy. The BiVO 4 -based photoanode obtained shows a high photocurrent density of 3.15 mA/cm2 at 1.23 V RHE and low onset potential. Detailed experiments and theoretical calculations show that during the activation of CoZn-MOFs, there was a partial breakage of 2-methylimidazole (mIM) linker, an increase in the oxidation state of Cobalt ion (Co), and increased O2–. The high PEC performance is mainly attributed to the MOF-derived CoOOH, which provides rich active sites for hole extraction and reduces the overpotential for oxygen evolution reaction. Furthermore, when CoZnNiFe-LDHs were decorated on BiVO 4 using the ions exchange method, the photocurrent density of BiVO 4 /CoZnNiFe-LDHs photoanode got to 4.0 mA/cm2 at 1.23 V RHE , accompanied with high stability. This study provides insights into understanding the key role played by the structural transformation of MOF cocatalyst in PEC water splitting processes. [ABSTRACT FROM AUTHOR]

Hydrogen, renowned for its abundance and versatility, stands as a significant green energy alternative, especially when produced through water electrolysis. In this study, 2D/2D van der Waals heterostructure with graphene and WS 2 monolayer (GW) is constructed as electrocatalyst for hydrogen evolution reaction (HER). The cohesive energy and the binding energy per area for the GW heterostructure are found to be −0.39 eV and −18.9 meV/Å2 which confirms the structural stability as well as the weak binding of two monolayers. Furthermore, ten 3d transition metals are introduced as single atom catalyst (SAC) in the GW heterostructure (TM@GW) to enhance the catalytic performance. The ΔG H* for all TM@GW shows that there is an enrichment in the HER performance by 47–96 % upon the introduction of SAC, showcasing the superiority of Zn@GW heterostructure with an overpotential of 80 mV and the lowest kinetic barrier of 0.51 eV for the Volmer-Tafel reaction. This investigation provides valuable insight for modeling both van der Waals heterostructures and SACs to enrich catalytic performance. [Display omitted] • HER performance of Graphene/WS 2 van der Waals heterostructure is studied using DFT. • HER performance of TM@GW heterostructure is enhanced by about 47–96%. • Zn@GW vdW heterostructure is found to lowest overpotential of 80 mV. • Zn@GW has the lowest kinetic barrier of 0.51 eV for the Volmer-Tafel reaction. [ABSTRACT FROM AUTHOR]

In this study, a three-dimensional Multiphysics field model of a planar solid oxide fuel cell (SOFC) is established based on computational fluid dynamics methods. The study introduces a new interconnector design known as the triangular interconnector. The results indicate that compared with the conventional interconnector, the discrete arrangement of ribs has a positive impact on the uniformity of oxygen distribution and hydrogen consumption rate. Furthermore, the triangular interconnector under counter-flow effectively increases the value of current density under the ribs, and the triangular interconnector achieved optimal performance in counter-flow configuration. Compared with conventional interconnector in counter-flow, the peak power increased by 28.64%, even when considering pressure drop, the increased parasitic power only accounts for 4.19% of the cell output power. Moreover, compared to the conventional interconnector structure; the activation overpotential, concentration overpotential, ohmic overpotential, and contact overpotential of the triangular interconnector structure under counter-flow configuration are reduced by 27.6%, 63.9%, 39.3%, and 20%, respectively. In addition, the total overpotential is reduced by 42.6%, indicating that optimizing fuel cell performance by rearranging the ribs is a reliable method. • Design a triangular interconnector to enhance the oxygen concentration under the ribs. • The flow distribution dominates the temperature distribution, but the interconnector influences the highest temperature. • Triangular interconnectors improve both cell power and net power. • Triangular interconnectors under counter-flow reduce overpotential. [ABSTRACT FROM AUTHOR]

Cu2O doped with atomically dispersed Rh (Rh:Cu2O) is synthesized with a wet chemical method. It shows higher activity and faradaic efficiency at lower overpotential for reduction of CO2 to C2+ products, especially C2H4, than pristine Cu2O. We found that introducing Rh promotes CO2 adsorption, *CO hydrogenation to *CHO and their coupling to O*CCHO intermediates, which contributes to enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

A novel Fe, Co-CeO 2 /CeF 3 @MXene heterostructure with Fe-Co dual active sites and oxygen vacancies has been prepared for alkaline water/real seawater OER. [Display omitted] • Fe, Co-CeO 2 /CeF 3 @MXene heterostructure with Fe-Co dual active sites was synthesized by energy-free consumption co-deposition method. • Fe，Co-CeO 2 /CeF 3 @MXene can function as highly effective electrocatalyst toward OER. • The adsorption evolution mechanism and the lattice oxygen mechanism synergistically enhanced the OER activity. • Wind and solar-energy-assisted water electrolysis devices show their promising prospects for green hydrogen production sustainably. Exploring low-cost, high-activity, and structurally stable nonprecious metal electrocatalysts for sluggish oxygen evolution reaction (OER) is paramount for water electrolysis. Herein, we successfully prepare a novel Fe,Co-CeO 2 /CeF 3 @MXene heterostructure with Fe–Co dual active sites and oxygen vacancies for alkaline OER using an energy-free consumption co-deposition method. Impressively, Fe,Co-CeO 2 /CeF 3 @MXene achieves an ultralow overpotential of 192 mV and a long-term stability of 110 h at 10 mA cm−2 without structural changes, thereby outperforming the commercial IrO 2 (345 mV). In addition, Fe,Co-CeO 2 /CeF 3 @MXene exhibits much superior activity (271 mV) and durability to IrO 2 (385 mV) in the real seawater OER. Wind- and solar energy-assisted water electrolysis devices show their promising prospects for sustainable green hydrogen production. Characterization techniques and theoretical calculations reveal that the Fe,Co co-implanted CeO 2 /CeF 3 heterostructure effectively degrades the energy barrier of the OER and optimizes the adsorption strength of *OH, *O, and *OOH intermediates. It exhibits the dual coupling mechanism of the adsorbed evolution and lattice oxygen mechanisms, which synergistically improves the OER performance. This work provides a facile and efficacious strategy for synthesizing a new class of heterostructures to achieve significant enhancement in the activity and stability of OER catalysts. [ABSTRACT FROM AUTHOR]

Modern civilization has been highly suffering from energy crisis and environmental pollutions. These two burning issues are directly and indirectly created from fossil fuel consumption and uncontrolled industrialization. The above critical issue can be solved through the proper utilization of green energy sources where no greenhouse gases will be generated upon burning of such materials. Hydrogen is the most eligible candidate for this purpose. Among various methods of hydrogen generation, electrocatalytic process is one of the most efficient methods because of easy handling and high efficiency. In these aspects Co‐based nanomaterials are considered to be extremely significant as they can be utilized as efficient, recyclable and ideal catalytic system. In this article a series of Co‐based nano‐electrocatalysts has been discussed with proper structure‐property relationship and their medium dependency. Therefore, such type of stimulating summary on recently reported electrocatalysts and their activity may be helpful for scientists of the corresponding field as well as for broader research communities. This can be inspiration for materials researchers to fabricate active catalysts for the production of hydrogen gas in room temperature. [ABSTRACT FROM AUTHOR]

The novel two–dimensional MXene material Ti3C2Tx has the advantages of a large specific surface area, adjustable band gap, good electrical conductivity, and high stability. However, the precipitation of hydrogen via electrolytic water splitting over Ti3C2Tx has unacceptably slow kinetics. In this paper, Co nanoparticles were incorporated on the Ti3C2TxMXene surface via electrostatic adsorption by utilizing the intrinsic MXene defects generated during the etching process. Next, a Fe−Co alloy structure was also constructed on the Ti3C2TxMXenesurface by wet chemical impregnation method using the principle of galvanic coupling substitution. The prepared catalyst had an overpotential of 118 mV at a current density of 10 mA‐cm−2 and a Tafel slope of 97.56 mV dec−1. The Fe−Co alloy structure accelerated the kinetic hydrogen precipitation step, and Fe−Co/Ti3C2Txshowed excellent stability when used in a water electrolysis process for 11 h. This work offers a promising strategy for the synthesis of intrinsically defective synthetic alloy MXene structures. [ABSTRACT FROM AUTHOR]

The study examines the oxygen evolution reaction (OER) electrocatalytic efficiency of various stainless‐steel mesh (SSM) sizes in electrolytic cells. Stainless steel is chosen due to its widespread availability and stability, making it an economically viable option. The primary objective of this investigation is to determine the optimal stainless‐steel mesh size among those currently widely available on the market. The classification of stainless‐steel mesh sizes as SS304 is confirmed by the minimal compositional variations observed across all mesh sizes through electron dispersive X‐ray (EDX) spectra and X‐ray fluorescence (XRF) analyses. Remarkably, CV experiments carried out at different scan rates indicate that SSM 200 has the maximum specific electrochemical surface area (ECSA). As a result, SSM 200 demonstrates superior performance in terms of current density response and shows the lowest overpotential in the alkaline medium compared to other stainless‐steel mesh sizes. Furthermore, the SSM 200 exhibits a low overpotential of 337 mV at a current density of 10 mA/cm2 and a Tafel slope of 62.2 mV/decade, surpassing the performance of several previously reported electrodes for the OER. Stability tests conducted under constant voltage further confirm the remarkable stability of SSM 200, making it an ideal anode for electrolytic cell applications. These findings emphasize the cost‐effectiveness and high stability of SSM 200, presenting intriguing possibilities for future research and advancements in this field. [ABSTRACT FROM AUTHOR]

A systematic theoretical study probing the catalytic potential of metal-doped SnO2(110) was conducted. The incorporation of metals such as Zr, Ti, W, V, Hf, and Ge is shown to drive electron transfer to Sn. The increased charge of Sn is injected into anti-bonding orbitals, finely tuning the catalytic activity and reducing the overpotential to −0.34 V. AIMD simulations show the stability of the modified structures. This work sheds light on the rational design of low-cost metal oxides with a high catalytic performance for CO2ER to formate. [ABSTRACT FROM AUTHOR]

The paper reports the development of Cu-doped NiCo 2 O 4 ternary inverse spinel oxides through microwave-assisted hydrothermal method as effective catalysts for alkaline hydrogen evolution reaction (HER). The effective and controlled doping of Cu to NiCo 2 O 4 lattice by the partial replacement of Ni2+/Ni3+ with Cu+/Cu2+ results in the fine-tuning of structural, morphological, and electronic characteristics, favourable for electrocatalytic HER. The study effectively correlates the influence of variation in the percentages of Cu-doping on the material properties and thereby the electrocatalytic characteristics. The experimental results indicate that Cu 0.10 Ni 0.90 Co 2 O 4 electrode having optimum Cu-doping (10%) as the best electrocatalyst with the lowest onset potential for hydrogen evolution (242.7 mV) and reduced overpotential (72.5 mV) values by following a Volmer – Heyrovsky mechanism during HER. The improvement in HER performance after Cu-doping is due to the generation of greater number of active sites and reduction in electronic band gap. The present work advantageously utilises the scope of microwave-assisted transition metal doping strategy to fine tune the physicochemical and electronic characteristics, favourable for electrocatalytic HER, and this may pave a new way for tuning the electrochemical properties of metal oxides for various applications. • Microwave-assisted hydrothermal synthesis is used effectively to develop Cu-doped NiCo 2 O 4. • Cu-doping to NiCo 2 O 4 lattice creates more oxygen vacancies and improves electronic conductivity. • Cu 0.10 Ni 0.90 Co 2 O 4 with 10% Cu-doping exhibits promising electrocatalytic activity towards HER. • Cu-doped NiCo 2 O 4 follows Volmer – Heyrovsky mechanism during alkaline HER. [ABSTRACT FROM AUTHOR]

Water splitting is considered a renewable and eco−friendly technique for future clean energy requirements to realize green hydrogen production, which is, to a large extent, hindered by the oxygen evolution reaction (OER) process. In recent years, two−dimensional (2D) carbon−based electrocatalysts have drawn sustained attention owing to their good electrical conductivity, unique physicochemical properties, and excellent electrocatalytic performance. Particularly, it is easy for 2D carbon−based materials to form nanocomposites, which further provides an effective strategy for electrocatalytic applications. In this review, we discuss recent advances in synthetic methods, structure−property relationships, and a basic understanding of electrocatalytic mechanisms of 2D carbon−based electrocatalysts for water oxidation. In detail, precious, non−precious metal−doped, and non−metallic 2D carbon−based electrocatalysts, as well as 2D carbon−based confined electrocatalysts, are introduced to conduct OER. Finally, current challenges, opportunities, and perspectives for further research directions of 2D carbon−based nanomaterials are outlined. This review can provide significant comprehension of high−performance 2D carbon−based electrocatalysts for water-splitting applications. [ABSTRACT FROM AUTHOR]

Herein, a novel Pt anchoring WO3 nanoarray catalyst is reported and its application as HzOR and HER bifunctional electrocatalysts which shown to have superior bifunctional performance for HzOR/HER under alkaline conditions. The Pt/WO3/NF requires an ultrasmall overpotential of 34.6 and 226.38 mV to achieve 10 and 100 mA cm−2 for the hydrazine oxidation reaction (HzOR), respectively. When used for HER-HzOR electrolysis, Pt/WO3/NF requires low voltages of 0.717 V and 1.049 V at 100 and 200 mA cm−2, respectively. [ABSTRACT FROM AUTHOR]

Developing an accessible and durable catalyst with minimal overpotentials to split water to produce both H 2 and O 2 is challenging. The hydrothermal-deposition precipitation route was adopted to synthesize α-Ag 2 WO 4 (20–80%) supported on α-Mn 3 O 4 (AgW/Mn). The 60%AgW/Mn catalyst, which is structurally made up of Mn platelets decorated with AgW nanoparticles, confirmed the existence of the MnO 2 (200) active sites, surpassing the Ag nanoparticles (54.3%), and the proportion of the birnessite Mn3+/4+ moieties. In comparison to other catalysts, it presented more selectivity for OER in 1.0 M KOH with a low overpotential (0.28 V) at 10 mA cm−2, a Tafel slope of 50.7 mV dec−1, an O 2 -equivelent amount of 221.5 mmolg−1, and a TOF of 1.17 s−1. Similarly, it produced HER at an overpotential of 0.089 V at η10, a Tafel slope of 73.35 mV dec−1, an H 2 -generated amount of 429.4 mmol g−1, and a TOF of 1.59 s−1. [Display omitted] • α-Ag 2 WO 4 (20–80%) supported on α-Mn 3 O 4 was synthesized by deposition precipitation. • Mn platelets including Mn3+, Mn4+, and Mn2+ decorated by Ag@α-Ag 2 WO 4 nanoparticles. • 60%AgW/Mn catalyst is an efficient water splitting electrocatalyst. • The overall splitting of the 60% catalyst indicates a potential of 1.54 V at η10. • The highest activity was based on the birnessite and Mn2+ ratio and Ag nanoparticles. [ABSTRACT FROM AUTHOR]

The objective of this study was to report electrocatalytic activity of tin selenide (SnSe) for oxygen evolution process (OER) and hydrogen evolution reaction (HER). Simple and inexpensive SnSe thin films were deposited onto a steel substrate using an electrodeposition method. Orthorhombic SnSe required a low overpotential value of 325, 317, 314 mV for OER and a low overpotential value of 273, 219, 194 mV for HER for SnSe-1, SnSe-2, and SnSe-3 electrodes, respectively, to reach a current density of 10 mA/cm2. The thickness of thin film increased over time 50, 60, and 70 min for each successive SnSe-1 to SnSe-3 samples. SEM image indicated crystalline in nature with compact grain-like morphology on the entire surface of the substrate. The SnSe-3 sample displayed low Tafel slopes of 90 and 68 mV/dec for OER and HER, respectively. EDX showed that atomic percentage ratio of Sn: Se was 54:46 for SnSe-3 thin film. Overall results suggest that electrochemically synthesized SnSe is a promising candidate as an efficient electrocatalyst for overall water splitting. [Display omitted] • Electrodeposited SnSe thin films were successfully synthesized. • The influence of deposition time on catalytic performance was examined. • Electrocatalytic analysis of SnSe was performed to capabilities of OER and HER. • The catalytic activity exhibited stability over a period of 12 h. [ABSTRACT FROM AUTHOR]

Various strategies have been adopted to enhance the characteristics of the MoO 2 nanoparticles electrode structures. Meanwhile the alkaline medium exhibits the sluggish kinetic and an acidic medium can donate the excess protons to promote the hydrogen evolution reaction. The annealing temperature may sputter the environmental oxygen from the surface and enhance the characteristics of the electrocatalysts. MoO 2 nanoparticles have been synthesized successfully using the hydrothermal process; later on, the synthesized structure was treated at temperatures of 400 and 600 °C under the flow of N 2 gas for 6 h. The heat treatment process at 600 °C influenced the characteristics of MoO 2 nanoparticles and enhanced the electrical conductivity, electrochemical and specific surface area and mesoporous features of MoO 2 -600 nanoparticles. Owing to boosted characteristics, MoO 2 -600 nanoparticles reveal a good overpotential of 56 mV at the current density of 10 mA cm−2 in 0.5 M H 2 SO 4 due to the excess availability of the protons, which is better than pre-annealed MoO 2 -basic and MoO 2 -400 nanoparticles. MoO 2 -600 nanoparticles exhibit a good Tafel slope of 22 mV dec−1 and follow the Tafel mechanism, while MoO 2 -600 nanoparticles show a Tafel slope of 64 and 67 mV dec−1 in buffer solution and 1 M KOH electrolyte, respectively. Moreover, the turnover frequency of MoO 2 -600 nanoparticles has been found as 191 ms−1 at the fixed reversible hydrogen potential of 800 mV RHE in 0.5 M H 2 SO 4 , which is greater than the buffer solution and 1 M KOH electrolyte. The results indicate that MoO 2 -600 nanoparticles are an effective electrocatalyst for hydrogen evolution reactions. • The annealing temperature may sputter the environmental oxygen from the surface. • MoO 2 -600 nanoparticles exhibited a greater electrical conductivity area. • MoO 2 -600 nanoparticles reveal a good overpotential of 56 mV in 0.5 M H 2 SO 4. • MoO 2 -600 nanoparticles exhibit a good Tafel slope of 22 mV dec−1 in 0.5 M H 2 SO 4. • The electrocatalyst MoO 2 -600 nanoparticles showed a higher TOF of 191 m s−1. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) is the key anode reaction of electrolytic water. To improve the slow OER kinetics, we synthesize nanoflower‐like Co−Fe‐Cr−Mo‐Mn high‐entropy spinel (HES) nanosheets on nickel foam (NF) by one‐step solvothermal method, which exhibit an overpotential (η10) of only 188 mV at 10 mA cm−2, much lower than bimetallic CoFeOx/NF (233 mV), trimetallic CoFeCrOx/NF (211 mV), and tetrametallic CoFeCrMoOx/NF (200 mV). The OER overpotential decreases with the increase of the number of metals, indicating that the formation of HES has a positive effect on the improvement of electrocatalytic performance, since the synergistic effect between different metals enhances the charge transfer rate and decreases reaction barrier. In‐situ Raman spectra demonstrate that the formation of γ‐NiOOH on the HES surface is a crucial active species for the OER. This work demonstrates a simple and efficient synthesis method to prepare nanoflower‐like high‐entropy electrocatalysts for efficient OER electrocatalysis. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4), as a carbon support material with excellent stability and abundant active sites, has found widespread applications in various fields, including photocatalytic water splitting, electrolysis of water, and CO2 reduction. Presently, research on the modification of g-C3N4 primarily focuses on atomic doping, defect engineering, and the decoration of metal nanoparticles. In this study, a method involving the high-temperature pyrolysis of a solution containing thiourea and urea was successfully employed to synthesize sulfur-doped porous g-C3N4 (S-C3N4) nanosheets. Subsequently, PtCu nanoparticles were loaded onto the S-C3N4 through a hydrothermal process. In the case of Pt loading of less than half of 20% Pt/C, this catalyst exhibited a low overpotential of only 10 mV at a current density of 10 mA cm−2, which is significantly better than the 35 mV overpotential of 20% Pt/C. Furthermore, after a long period of continuous current stability testing, the overpotential of the catalyst did not increase by more than 30 mV, demonstrating excellent stability. The porous S-C3N4 nanosheets possess a large specific surface area, providing abundant active sites for the HER reaction. This research introduces a fresh method for creating innovative catalysts based on Pt alloys supported by a carbon carrier. [ABSTRACT FROM AUTHOR]

Graphdiyne (GDY) is considered a very attractive support for metal nanocatalysts due to its unique structure and superior properties. The metal–GDY interaction can significantly affect the performance of catalysts. Herein, GDY nanotubes abundant in in situ formed Cu quantum dots (QDs) (Cu-GDYNT) are prepared using the electrospun polyacrylonitrile nanofibers collected on the surface of electrolytic Cu foil as templates. The diameter of the Cu-GDYNT is controllable and the uniform size of the embedded Cu QDs is about 2.2 nm. And then, the uniformly dispersed and highly active supported catalysts of ruthenium nanoparticles (Rux/Cu-GDYNT) are produced using the Cu-GDYNT as the support. Among them, the Ru3/Cu-GDYNT exhibit outstanding HER performance at all pH levels. Only 17, 67 and 83 mV overpotential is required to reach a current density of 10 mA cm−2 in 1.0 M KOH, 0.5 M H2SO4 and 1.0 M neutral PBS solutions, respectively. The sample exhibits 3000 CV cycle stability and 20 h continuous electrolysis without performance degradation in an alkaline medium. This work provides a new idea for constructing the GDY-supported metal nanocatalysts. [ABSTRACT FROM AUTHOR]

Low-cost and highly efficient cathode and anode materials are required for proton exchange membrane and alkaline water electrolyzers. The present work demonstrates the development of a bifunctional cathode and anode material for hydrogen and oxygen evolution reactions (HER/OER) in an alkaline environment. The bimetallic Ni–Mo selenide is fabricated over the MXene (Ti 3 C 2 T x) grown over the activated carbon fibers by an inexpensive, simple one-step and eco-friendly approach. The electrocatalyst NiMoSe/Ti 3 C 2 T x @CC is developed via a hydrothermal method wherein NiMoSe is observed to grow highly dense nanoporous structure as confirmed by various characterization techniques. Highest activity for HER is observed using NiMoSe/Ti 3 C 2 T x @CC with only overpotential of 203 mV at 10 mA cm−2 with low Tafel slope (45 mV dec−1). The catalyst is also proven to support OER activity with requirement of 320 mV as overpotential at 10 mA cm−2, thus better than commercial IrO 2 (η 10 = 380 mV). The Tafel slope obtained by NiMoSe/Ti 3 C 2 T x @CC for OER is found to be minimum (189 mV dec−1) along with a very low charge transfer resistance (3.04 Ω) and high electrochemical surface area (0.0378 mF cm−2). The NiMoSe/Ti 3 C 2 T x @CC is found to be highly stable for HER/OER with 1000 LSV cycles. The work highlights the development of a cost-effective and efficient Ti 3 C 2 T x (MXene) based bifunctional electrocatalyst for oxygen evolution and hydrogen evolution reactions (OER/HER) in an alkaline medium (1 M KOH). The bimetallic Ni–Mo selenide is fabricated over the MXene on the activated carbon fibers by an inexpensive, simple, one-step hydrothermal method. The highly dense nanoporous structure shows an overpotential of 203 mV at 10 mA cm−2 for HER in alkaline medium. The corresponding overpotential for OER is 320 mV which has been found better than commercial IrO 2 catalyst (η 10 = 380 mV). In addition, NiMoSe/Ti 3 C 2 T x @CC bears a high electrochemically active surface area (0.0378 mF cm−2), low charge transfer resistance (3.04 Ω), and high stability (1000 LSV cycles) for both OER and HER. [Display omitted] • Bifunctional NiMoSe/Ti 3 C 2 T x @CC was synthesized via one step hydrothermal route. • Overpotential (η 10) for HER was found to be 203 mV. • For OER, overpotential (η 10) was found 320 mV, better than commercial IrO 2. • 1000 LSV cycle and 30 h stability was conducted for HER and OER. [ABSTRACT FROM AUTHOR]

Due to its cost-effectiveness and high product selectivity, tin oxide has been regarded as a promising catalyst for the electrochemical conversion of CO2 to formate. However, formate production is hindered by the high overpotential; there is a need to reduce the overpotential to enhance energy efficiency and lower electricity cost for the implementation of carbon utilization technology. Here, we report a facile synthesis method for 1 nm-sized SnO2 cluster catalysts, which can be used for CO2-to-formate conversion. SnO2 clusters were prepared through impregnation of porous carbon with a tin precursor solution. The SnO2 clusters showed a low overpotential, generating a current density of 10 mA cm-2 at a potential of -0.34 V vs. RHE in 1 M KOH. They also achieved high Faradaic efficiencies of 90.5% and 81.5% at 200 and 300 mA cm−2, respectively. Their electrocatalytic performance was strongly dependent on the annealing conditions, which affected the particle size, electrochemical active surface area, and metal oxidation state. This paper presents a versatile method for synthesizing metal oxide cluster catalysts, apart from providing insights into the catalytic activity for the electrochemical conversion of CO2 to formate. [ABSTRACT FROM AUTHOR]

We present a facile and scalable method to synthesize Pt/C catalysts with high Pt loading (10–30 wt.%) using sodium polyacrylate resin (PAANa) as a multifunctional agent. PAANa can absorb H 2 PtCl 6 solution and form a gel, which can be converted into Pt/C catalysts by pyrolysis. PAANa acts as a water absorber, a Pt stabilizer, and a carbon precursor. The optimized catalyst, pyrolyzed at 800 °C with a 20 wt.% Pt loading, demonstrates Pt nanoparticles measuring 3.5 nm in size. It exhibits excellent stability and achieves a low overpotential of 43 mV at a current density of 10 mA cm−2 for the hydrogen evolution in alkaline media. The enhanced catalytic activity is due to the combined influence of the nanoscale Pt particles, the higher degree of graphitization, and the porous carbon substrate with a large surface area. We also demonstrate the scalability of the method by producing 100 g of the catalyst in the laboratory. [Display omitted] • Using PAANa as a multifunctional agent solves challenge of synthesizing high Pt loading Pt/C. • Pt/C catalyst demonstrates excellent performance with low overpotential and high stability. • Scalable method enables synthesis of Pt/C (100 g) for potential industrial applications. [ABSTRACT FROM AUTHOR]

IrO2 is a current state-of-the-art catalyst for polymer electrolyte membrane water electrolyser (PEMWE) applications due to its high stability during the oxygen evolution reaction (OER). However, its activity needs to be significantly improved to justify the use of such a high-cost material. In this study, the activity of the IrO2 catalyst was improved by optimising and comparing two synthesis methods: the modified Adams fusion method (MAFM) and the molten salt method (MSM). Optimum OER performances of the IrO2 catalysts synthesised with the two synthesis methods were obtained at different temperatures. For the MAFM, a synthesis temperature of 350 °C produced the IrO2 catalyst with an overpotential of 279 mV and the highest OER stability of ~ 82 h at 10 mAcm-2. However, for the MSM, the lowest overpotential of 271 mV was observed for IrO2 synthesised at 350 °C, while the highest stability of ~ 75 h was obtained for the IrO2 synthesised at 500 °C. [ABSTRACT FROM AUTHOR]

The high overpotential caused by the slow kinetics of oxygen reduction (ORR) and oxygen evolution (OER) has greatly limited the practical application of lithium‐oxygen (Li−O2) batteries. The adoption of force‐field‐assisted system based on a newly developed piezocatalysis is promising in reducing the overpotential. Herein, a force‐assisted Li−O2 battery is first established by employing MoS2/Pd nanocomposite cathode, in which the piezoelectric polarization as well as built‐in electric field are formed in MoS2 piezoelectric catalyst under ultrasound activation, leading to the continuously separated electrons and holes to enhance the ORR and OER kinetics. Moreover, the introduction of Pd can promote the electrons transfer and further inhibit the complexation of electron–hole pairs, contributing to enhanced catalytic activity in the decomposition/generation of discharge products, resulting in reduced discharge/charge overpotentials. Thus, the force‐assisted MoS2/Pd‐based Li−O2 battery is capable of adjusting the output and input energies by the assisted ultrasonic wave. An ultra‐low charging platform of 2.86 V and a high discharging platform of 2.77 V are achieved. The proposed unique force‐assisted strategy can also be applied to lithium carbon dioxide battery system through the effective reduction and separation of CO2 and CO32−, providing significant insights in achieving efficient energy conversion for metal−air batteries. [ABSTRACT FROM AUTHOR]

The practical application of CO2 electroreduction to CO driven by renewable electricity should simultaneously meet the requirements of low overpotential, high CO faradaic efficiency (FE), and low cost. Herein, a new strategy is reported to construct a porous nanoflower Ni–Al NC catalyst with excellent catalytic activity via p–d orbital hybridization of Al and Ni. The optimized Ni–Al NC catalyst exhibits an outstanding CO2 electroreduction activity with the maximum CO FE of 98%, low onset potential of −0.5 V vs. RHE, and wide FECO plateau (>90% from −0.7 to −1.0 V vs. RHE), showing great promise for practical applications. The experimental results showed that the p–d hybrid Ni–Al NC catalyst not only enriched its reaction sites but also withstood potential changes in the highly selective reduction of CO2 to CO. This study provides a catalyst design strategy for the efficient electrocatalytic reduction of CO2 to CO under varying potentials. [ABSTRACT FROM AUTHOR]

Nickel-iron oxy/hydroxides (NiFeOxHy) emerge as an attractive type of electrocatalysts for alkaline water oxidation reaction (WOR), but which encounter a huge challenge in stability, especially at industrial-grade large current density due to uncontrollable Fe leakage. Here, we tailor the Fe coordination by a MXene-mediated reconfiguration strategy for the resultant NiFeOxHy catalyst to alleviate Fe leakage and thus reinforce the WOR stability. The introduction of ultrafine MXene with surface dangling bonds in the electrochemical reconfiguration over Ni-Fe Prussian blue analogue induces the covalent hybridization of NiFeOxHy/MXene, which not only accelerates WOR kinetics but also improves Fe oxidation resistance against segregation. As a result, the NiFeOxHy coupled with MXene exhibits an extraordinary durability at ampere-level current density over 1,000 h for alkaline WOR with an ultralow overpotential of only 307 mV. This work provides a broad avenue and mechanistic insights for the development of nickel-iron catalysts toward industrial applications. [ABSTRACT FROM AUTHOR]

The collaborative interaction between the diatoms can enhance the catalytic activity of the transition metal atoms and facilitate the activation of nitrogen molecules. Based on first-principles calculations, the feasibility of electrocatalytic nitrogen fixation as a diatomic catalyst (TMs@MoSSe) formed by transition metal dimers (V, Cr, Mn, Fe, Co, and Ni) dispersed on a two-dimensional Janus MoSSe monolayer is systematically investigated. The results demonstrate that the MoSSe monolayer loaded with double chromium atoms (Cr2@MoSSe) exhibits exceptional catalytic activity, showcasing an extremely low overpotential of 0.17 V in the enzymatic mechanism. Specifically, this research elucidates the nitrogen reduction capacity of the electrocatalyst by considering its magnetic moment and work function, concluding that a lower work function corresponds to enhanced catalytic activity. Additionally, the product of the magnetic moment and valence electron numbers of the transition metal atoms ( μ T M ⋅ d T M ) exhibits an inverted volcano relationship with the overpotential. These findings can provide valuable insights for the design of diatomic catalysts. [ABSTRACT FROM AUTHOR]

Designing efficient electrocatalysts for hydrogen generation is desirable for electrochemical water splitting and fuel cells as they are a part of clean and sustainable energy system. Here, we are reporting the utilization of clean method for the production of platinum deposited chromium disulphide (CrS 2) particles and their application for hydrogen generation via photo-assisted electrochemical water splitting. Photoelectrochemical studies of CrS 2 show a close to zero onset potential, ultralow overpotential (8.3 mV), small Tafel slope (54 mV/decade), and low impedance (1.8 Ω) in acidic media. The chronoamperometric study of prepared catalyst reveals that it is sustainable as having a long-term stability. The post electrochemical study of electrode surface reveal the presence of traces of Pt deposited over CrS 2. The detailed compositional analysis of electrolyte has also been performed. This study opens up a pathway for electrochemically modifying the composition of the catalysts for harnessing their potential as efficient electrocatalyst during water splitting. [Display omitted] • Monoclinic CrS 2 Particles were obtained via one step pyrolysis method. • Platinum has been deposited electrochemically on CrS 2. • Prepared nanocomposites show excellent HER activity at near-zero onset potential. [ABSTRACT FROM AUTHOR]

The metal–organic framework (MOF) materials with large active sites and excellent catalytic properties have attracted widespread attention and are expected to be promising for oxygen evolution reaction (OER) for water splitting. Herein, we report a new and efficient heterogeneous nanostructure OER system constructed by a bimetallic 2D-layered porous metal–organic framework (Cu/Ni-MOF) and semiconductor nano-TiO2 particles. The bimetallic MOF can control its porous layered morphology by adjusting the ratio of surfactants. The OER performance of the hybrid system can be enhanced by introducing nano-TiO2 particles, and the performance of reducing the overpotential value is about 2.4 times higher than the pure Cu/Ni-MOF. Under illumination, the overpotential (η=10) is only 79 mV, which is much lower than the pure Cu/Ni-MOF (189 mV). At the same time, it can still maintain a low overpotential value of 168 mV after a 24 h stability test. This study also briefly tested the catalytic performance of the material in hydrogen evolution reaction (HER), and under the illumination conditions, the overpotential (η = 10) is 209 mV. Furthermore, it revealed the key role of bimetallic synergy and P–N heterojunction (via electrical and simulated photo-excited electrons) in boosting the OER performance of the system. The finding and proposed concept provide a new approach for synthesizing multi-metal MOFs and combining them with semiconductors to enhance the photoelectrochemical water splitting and open a new avenue to design high-performance MOF heterojunctions for photo-electrocatalysis. [ABSTRACT FROM AUTHOR]

Force-assisted lithium-carbon dioxide battery relies on piezoelectric catalysis principle to generated electrons and holes promote carbon dioxide reduction and evolution to improve battery performance, providing a new strategy for developing lithium-carbon dioxide battery in energy storage. [Display omitted] The use of light-assisted cathode is regarded as an effective approach to reduce the overpotential of lithium carbon dioxide (Li − CO 2) batteries. However, the inefficient electron-hole separation and the complex discharge–charge reactions hamper the efficiency of CO 2 photocatalytic reaction in battery. Herein, a highly reversible force-assisted Li − CO 2 battery has been established for the first time by employing a Bi 0.5 Na 0.5 TiO 3 nanorods piezoelectric cathode. The high-energy electron and holes generated by the piezoelectric cathode with ultrasonic force can effectively enhance the carbon dioxide reduction reaction (CDRR) and carbon dioxide evolution reaction (CDER) kinetics, thereby reducing the overpotentials during the discharge–charge processes. Moreover, the morphology of the discharge product (Li 2 CO 3) can be modified via the dense surface electrons of the piezoelectric cathode, resulting in the promoted decomposition kinetics of Li 2 CO 3 in charging progress. Thus, the force-assisted Li − CO 2 battery with the unique piezoelectric cathode can adjust the output and input energy by ultrasonic wave, and provides an ultra-low charging platform of 3.52 V, and exhibits excellent cycle stability (a charging platform of 3.42 V after 100 h cycles). The investigation of the force-assisted process described herein provides significant insights to solve overpotential in the Li − CO 2 batteries system. [ABSTRACT FROM AUTHOR]

Heterogeneous interface engineering is an ideal technique for the rational design of efficient and low-cost electrocatalysts for oxygen evolution reactions (OER). In this study, a complex hydrothermal-electrodeposition composite approach was used to insert a Ni(OH) 2 interlayer into the tiny gaps between the layers of NiFe layered double hydroxides (NiFe LDHs), and the interlayer's influence on OER performance was examined. Benefiting from the support of Ni(OH) 2 interlayer, the resulting Ni(OH) 2 /NiFe LDHs could withstand 5000 CV-AST tests with just a 6 mV overpotential increase, as well as 50 h of long-term operation with negligible activity loss on a potential of 1.724 V RHE. Meanwhile, in the OER process, the Ni(OH) 2 /NiFe LDHs exhibit 220 mV overpotential and 48.5 mV dec−1 Tafel slope in 1 M KOH solution, which is superior to NiFe LDHs, RuO 2 , and IrO 2. Additionally, Ni(OH) 2 /NiFe LDHs show a high-polarization-potential stability during i-t tests. At 1.824 V RHE , the Ni(OH) 2 /NiFe LDHs could afford 12 h operation with ∼0.35 % activity loss, which was better than on a low potential of 1.624 V RHE (12 h, ∼8.4 % activity loss). This composite strategy may provide an effective method for optimizing other LDHs, as well as a new route for building high-activity and durable OER catalysts for practical water splitting. [ABSTRACT FROM AUTHOR]

MoS 2 nanostructures are famous electrocatalysts in hydrogen evolution reaction (HER). The presence of graphene was already reported to boost the electrocatalytic activity of MoS 2. This work reports the influence of Sulphur deficiency and economically synthesizable green carbon dot (GCD) incorporation into hydrothermally synthesized MoS 2 nanostructures on the electrocatalytic activity of HER. All as-synthesized nanocatalysts are Sulphur deficient (MoS 2−x and GCD-MoS 2−x) and exhibited superior HER activity as compared to commercial MoS 2. MoS 2−x 220 exhibited a Tafel slope of 43 mV/Dec indicates the reaction mechanism as Volmer-Heyrovsky with Heyrovsky as rate determining step. Best electrocatalytic parameters are observed for the same catalyst with overpotential: 247 mV at 10 mA/cm2, Turnover frequency: 0.42 s−1, double layer capacitance: 23.8 mF/cm2 and electrochemically active surface area: 595/cm2. The obtained preferable HER parameters suggest that Sulphur deficiency and incorporation of GCD in MoS 2 are playing a vital role in HER electrocatalysis. [Display omitted] • HER activity of MoS 2 nanostructures on sulphur deficiency and GCD incorporation. • The effect of electrocatalytic activity of MoS 2 in the presence of GCD: A novel study. • Detailed examination of HER mechanism. • MoS 2−x 220 exhibited best overpotential:247 mV, Tafel slope:43 mV/Dec, TOF:0.42 s−1. [ABSTRACT FROM AUTHOR]

Recent experiments have demonstrated that 1T phase of transition-metal dichalcogenides exhibits superior electro-catalytic activity for hydrogen evolution reaction (HER). Herein, we compare the HER performance of as obtained 2H-phase MoSe 2 (bare) with hydrothermally synthesized 1T-2H mixed phase MoSe 2 and its composites with reduced graphene oxide. Obtained MoSe 2 /rGO composite has displayed a Tafel slope of 55 mV dec−1 compared with mixed-phase (113 mV dec−1) and 2H–MoSe 2 (125 mV dec−1, bare). Composite of MoSe 2 with very small amount of rGO has shown increased HER activity with low overpotential (88 mV at 10 mA cm−2), smaller Tafel slope, longer durability and high value of turn over frequency. The weight ratio between MoSe 2 and rGO is crucial in determining the HER performance of the composite. The Present work offers a facile and attractive methodology for enhancing the HER performance of 2D materials-based electrocatalysts. • MoSe 2 /rGO composites were synthesized via facile hydrothermal route. • Presence of 1T/2H–MoSe 2 phase improved the catalytic properties. • Weight ratio between MoSe 2 and rGO plays a key role in HER kinetics. • MoSe 2 /rGO composite with ideal weight ratio possesses lower Tafel slope (55 mVdec−1). • Lower overpotential and charge transfer resistance give smaller Tafel slope in composite. [ABSTRACT FROM AUTHOR]

In this study, the pristine MgO, MgO/CNT and Ni-MgO/CNT nanocomposites were processed using the impregnation and chemical vapor deposition methods and analyzed for hydrogen evolution reaction (HER) using the electrochemical water splitting process. Furthermore, the effect of nickel on the deposited carbon was systematically elaborated in this study. The highly conductive carbon nanotubes (CNTs) deposited on the metal surface of the Ni-MgO nanocomposite heterostructure provides a robust stability and superior electrocatalytic activity. The optimized Ni-MgO/CNT nanocomposite exhibited hierarchical, helical-shaped carbon nanotubes adorned on the surface of the Ni-MgO flakes, forming a hybrid metal–carbon network structure. The catalytic HER was carried out in a 1M alkaline KOH electrolyte, and the optimized Ni-MgO/CNT nanocomposite achieved a low (117 mV) overpotential value (ɳ) at 10 mA cm−2 and needed a low (116 mV/dec) Tafel value, denotes the Volmer–Heyrovsky pathway. Also, the high electrochemical active surface area (ECSA) value of the Ni-MgO/CNT nanocomposite attained 515 cm2, which is favorable for the generation of abundant electroactive species, and the prepared electrocatalyst durability was also performed using a chronoamperometry test for the prolonged duration of 20 h at 10 mA cm−2 and exhibited good stability, with a 72% retention. Hence, the obtained results demonstrate that the optimized Ni-MgO/CNT nanocomposite is a highly active and cost-effective electrocatalyst for hydrogen energy production. [ABSTRACT FROM AUTHOR]

Heterogeneous interface engineering is an ideal technique for the rational design of efficient and low-cost electrocatalysts for oxygen evolution reactions (OER). In this study, a complex hydrothermal-electrodeposition composite approach was used to insert a Ni(OH) 2 interlayer into the tiny gaps between the layers of NiFe layered double hydroxides (NiFe LDHs), and the interlayer's influence on OER performance was examined. Benefiting from the support of Ni(OH) 2 interlayer, the resulting Ni(OH) 2 /NiFe LDHs could withstand 5000 CV-AST tests with just a 6 mV overpotential increase, as well as 50 h of long-term operation with negligible activity loss on a potential of 1.724 V RHE. Meanwhile, in the OER process, the Ni(OH) 2 /NiFe LDHs exhibit 220 mV overpotential and 48.5 mV dec−1 Tafel slope in 1 M KOH solution, which is superior to NiFe LDHs, RuO 2 , and IrO 2. Additionally, Ni(OH) 2 /NiFe LDHs show a high-polarization-potential stability during i-t tests. At 1.824 V RHE , the Ni(OH) 2 /NiFe LDHs could afford 12 h operation with ∼0.35 % activity loss, which was better than on a low potential of 1.624 V RHE (12 h, ∼8.4 % activity loss). This composite strategy may provide an effective method for optimizing other LDHs, as well as a new route for building high-activity and durable OER catalysts for practical water splitting. [ABSTRACT FROM AUTHOR]

An important, yet difficult problem is the rational design and controlled production of an electrocatalyst for hydrogen evolution reaction (HER) using graphene-based bimetallic sulphide. Here, a novel electrocatalyst for HER was designed and created using a spherical-shaped structure grown on a graphene sheet with a conductive Cu-CoS2 support (rGO@CuCoS2). It takes advantage of the synergistic effect between the copper and cobalt sulphide phases, the naturally low resistance of the bimetal substrate, and the uniform spherical structure. With overpotentials of 84 mV at a current density of 10 mA cm−2 in alkaline electrolytes, the self-supported rGO@CuCoS2 composite catalyst demonstrates outstanding electrocatalytic activity for HER in an alkaline pH range, respectively. The created rGO@CuCoS2 catalyst impressively exhibits steady electrocatalytic activity and high durability in HER processes. The electrocatalytically accessible sites were also discovered to be 15.02 x 1017 sites at a 5 mV s−1 scan rate. This novel mix of methods is intended to offer a workable plan for the advancement of human energy and is promising much beyond the realm of water electrolysis. [ABSTRACT FROM AUTHOR]

Aqueous zinc ion batteries (AZIBs) with high safety, low cost, and eco‐friendliness advantages show great potential in large‐scale energy storage systems. However, their practical application is hindered by low Columbic efficiency and unstable zinc anode resulting from the side reactions and deterioration of zinc dendrites. Herein, tripropylene glycol (TG) is chosen as a dual‐functional organic electrolyte additive to improve the reversibility of AZIBs significantly. Importantly, ab initio molecular dynamics theoretical simulations and experiments such as in situ electrochemical impedance spectroscopy, and synchrotron radiation‐based in situ Fourier transform infrared spectroscopy confirm that TG participates in the solvation sheath of Zn2+, regulating overpotential and inhibiting side reactions; meanwhile, TG inhibits the deterioration of dendrites and modifies the direction of zinc deposition by constructing an adsorbed layer on the zinc anode. Consequently, a Zn‐MnO2 full cell with TG electrolyte exhibited a specific capacity of 124.48 mAh g‐1 after 1000 cycles at a current density of 4 A g‐1. This quantitative regulation for suitable solvation sheath and adsorbed layer on zinc anode, and its easy scalability of the process can be of immediate benefit for the dendrite‐free, high‐performance, and low‐cost energy storage systems. [ABSTRACT FROM AUTHOR]

Exploring non-noble metal dual-functional electrocatalysts with high activity and stability for water splitting is highly desirable. In this study, using zeolitic imidazolate framework-L (ZIF-L) nanoarrays as the precursor, manganese oxide-decorated porous nickel–cobalt phosphide nanosheet arrays have been prepared on nickel foam (denoted as MnOx/NiCoP/NF) through cation etching, phosphorization and electrodeposition, which are utilized as an efficient dual-functional electrocatalyst for overall water splitting. The hierarchical porous nanosheet arrays provide abundant active sites for the electrochemical process, while the MnOx modification induces strong interfacial interaction, benefiting charge transfer. Thus, the MnOx/NiCoP/NF exhibits excellent electrocatalytic activity toward the hydrogen evolution reaction (HER, overpotential of 93 mV at 10 mA cm−2), oxygen evolution reaction (OER, overpotential of 240 mV at 10 mA cm−2) and overall water splitting (cell voltage of 1.59 V at 10 mA cm−2). Furthermore, it shows superior stability during continuous overall water splitting for 200 h. This work provides a simple and effective approach for developing efficient non-noble metal dual-functional catalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

The electrocatalytic mechanisms of CO2 reduction catalyzed by pyridine-oxazoline (pyrox)-based Mn catalysts were investigated by DFT calculations. In-depth comparative analyses of pyrox-based and bipyridine-based Mn complexes were carried out. C–OH cleavage is the rate-determining step for both the protonation-first path and the reduction-first path. The free energy of CO2 activation (ΔG1) and the electrons donated by CO ligands in this step are effective descriptors in regulating the C–OH cleavage barrier. The reduction of carboxylate complex 6 (E6) is the potential-determining step for the reduction-first path. Meanwhile, for the protonation-first path, the initial generation (E2) or the regeneration (E8) of active catalyst might be potential-determining. Hirshfeld charge and orbital contribution analysis indicate that E6 is definitely based on the heterocyclic ligand and E2 is related to both the heterocyclic ligand and three CO ligands. Therefore, replacement of the CO ligand by a stronger electron donating ligand can effectively boost the catalytic activity of CO2 reduction without increasing the overpotential in the reduction-first path. This hypothesis is supported by the mechanism calculations of the Mn complex in which the axial CO ligand is replaced by a pyridine or PMe3. [ABSTRACT FROM AUTHOR]

The electrocatalytic splitting of water to produce hydrogen is regarded as an efficient and promising strategy but is limited by its large overpotential; thus, a highly efficient electrocatalyst is urgently needed. Mixed metal doping is an important strategy in defect engineering because the heteroatoms can change the intrinsic structure to form defects by affecting the atomic coordination mode and adjusting the electronic structure, which is often accompanied by morphological changes. Herein, two-dimensional layered bimetallic Co–pydc containing axially coordinated water molecules was selected by producing surface defects through Fe doping in Co centers as bifunctional electrocatalysts for OER and HER. The optimized Co0.59Fe0.41–pydc possesses outstanding OER performance with the lowest overpotential of 262 mV to reach j = 10 mA cm−2, and Co0.75Fe0.25–pydc possesses superior HER performance with the lowest overpotential of 96 mV at j = 10 mA cm−2. Furthermore, the overall water splitting device assembled with Co0.59Fe0.41–pydc@NF//Co0.59Fe0.41–pydc@NF affords a current density of 10 mA cm−2 at only 1.687 V. This work emphasizes the surface defects formed by tuning the electronic structure of metal centres accompanied with morphological changes of bimetallic dopants for efficient overall water splitting. [ABSTRACT FROM AUTHOR]

Enhanced oxygen evolution reaction (OER) kinetics plays an important role in the large-scale production of hydrogen via water electrolysis. In this regard, the crystallinity of FeVO 4 is tuned from amorphous to semicrystalline and fully crystalline via precipitation followed by controlled thermal treatment. The prepared FeVO 4 samples show a uniform distribution of spherical nanoparticles (40–60 nm). The tailored amorphous, semicrystalline, and fully crystalline FeVO 4 samples are immobilized on nickel foam and their OER performance was studied. The OER performance of amorphous, semicrystalline, and fully crystalline FeVO 4 shows in the order of amorphous FeVO 4 > semicrystalline FeVO 4 > fully crystalline FeVO 4. The amorphous FeVO 4 demonstrates magnificent enhanced OER kinetics with a small overpotential and high current density compared to the semicrystalline and fully crystalline FeVO 4. The amorphous FeVO 4 exhibits an overpotential of 310 mV at a high current density of 1000 mA cm−2 and also exhibits exemplary stability over 95 h, while semicrystalline FeVO 4 and fully crystalline FeVO 4 respectively require 360 mV and 390 mV to drive a relatively lower current density of 500 mA cm−2. [ABSTRACT FROM AUTHOR]

Single-atom catalysts (SACs), distinguished by their exceptional atomic efficiency and modifiable coordination structures, find wide-ranging applicability, notably in the context of the hydrogen evolution reaction (HER). Herein, we synthesized a Ti3C2Tx-based Ni single-atom catalyst (Ni SA@N-Ti3C2Tx) by immersing a single Ni atom into the Ti vacancies of Ti3C2Tx and using a N-doping strategy. X-Ray adsorption fine structure revealed the formation of local Ni-N1C1 and an unsaturated C–Ni–N bridge configuration for isolated Ni species. Moreover, Ni SA@N-Ti3C2Tx exhibited an excellent HER performance with an overpotential of 63 mV at 10 mV cm−2. This work could enable use of MXene-based SACs in the HER. [ABSTRACT FROM AUTHOR]

Developing a cost-effective, efficient, and eco-friendly electrocatalyst made from non-noble materials for the hydrogen evolution reaction (HER) is challenging. This research paper presents an application of the nickel sulfide (Ni 3 S 2) nanowires-filled multiwalled carbon nanotubes (CNTs) synthesized on carbon cloth (CC) (Ni 3 S 2 @CNTs/CC) as an efficient HER electrocatalyst. The performance of Ni 3 S 2 @CNTs/CC as a working electrode was examined for its hydrogen evolution ability. In a 1.0 M KOH solution, Ni 3 S 2 @CNTs/CC requires cathodic overpotentials of 381 mV and 549 mV to generate current densities of 10 mA/cm2 and 100 mA/cm2, respectively. Electrochemical impedance measurements showed a low charge transfer resistance value of 3.3 Ω for Ni 3 S 2 @CNTs/CC. The evaluation of the electrochemically active surface area revealed that Ni 3 S 2 @CNTs/CC has more electrochemical active sites and a higher roughness factor than pristine CC. Most importantly, the current density of Ni 3 S 2 @CNTs/CC did not significantly degrade after 3000 CV cycles and 12 h of constant HER. These findings suggest that Ni 3 S 2 @CNTs/CC is a cost-effective, highly functional, and stable electrode material for HER in a strongly alkaline medium. [Display omitted] • Application of novel Ni 3 S 2 @CNTs/CC acting as an electrocatalyst for HER is reported for the first time. • The synthesized Ni 3 S 2 @CNTs promote water dissociation by facilitating the electron transfer process. • The enhanced catalytic HER activity of Ni 3 S 2 @CNTs/CC is attributed to the synthesized Ni 3 S 2 @CNTs on the CC substrate. • Ni 3 S 2 @CNTs/CC acts as a binder-free, flexible HER electrocatalyst. [ABSTRACT FROM AUTHOR]

The construction of efficient, sustainable, and low-cost nonprecious metal electrocatalysts for oxygen evolution reaction (OER) is necessary for the realization of electrocatalytic overall water splitting. Herein, the PW 6 Mo 6 /ZIF-67@NF is prepared using a simple coprecipitation method. Characterization results indicate that the PW 6 Mo 6 induces the exposure of Co nodes in ZIF-67, which can act as catalytic active sites for OER. Meanwhile, the introduction of PW 6 Mo 6 improves the conductivity and electrochemical active surface area of ZIF-67, which further enhances the OER performance. The electrochemical test results show that the PW 6 Mo 6 /ZIF-67@NF exhibit an ultralow overpotential of 201 mV at 10 mA cm−2 and a small Tafel slope of 55 mV dec−1 for OER, which is lower than that of ZIF-67@NF (329 mV, 286 mV dec−1). Our study demonstrates the potential of polyoxometalate and ZIF composites to decrease the barriers of OER and provides a feasible approach for exploring economical and practical electrocatalysts. The etching of PW 6 Mo 6 induces the exposure of Co active sites in ZIF-67, thereby PW 6 Mo 6 /ZIF-67@NF exhibit an ultralow overpotential of 201 mV at 10 mA cm−2 and a small Tafel slope of 55 mV dec−1 for OER. [Display omitted] • The PW 6 Mo 6 /ZIF-67@NF with exposed Co nodes was successfully prepared using a coprecipitation method. • The introduction of PW 6 Mo 6 improved the conductivity and electrochemical active surface area of ZIF-67. • The ZIF-67 framework prevents the dissolution of PW 6 Mo 6 in the electrolyte, thus increasing the stability. • The PW 6 Mo 6 /ZIF-67@NF exhibited an ultralow overpotential and a small Tafel slope for OER. [ABSTRACT FROM AUTHOR]

As traditional non-renewable energy sources become scarcer, researchers are exploring effective strategies for producing sustainable and renewable energy. Oxygen evolution reaction through electrocatalytic water splitting (EC-OER) on the surface of a semiconductor has drawn much more attention in the worldwide as it has the principal role towards the several kind of energy applications viz. fuel cell, metal-ion rechargeable batteries and water oxidation. It is extremely difficult to develop eco-friendly, plentiful, and cost-effective nanomaterials as catalysts in order to achieve high efficiency of hydrogen production through water splitting. Furthermore, hierarchical nanostructures will become more valuable in future energy conversion applications due to their excellent physicochemical properties. Herein, we have synthesized total six different kinds of multi-metal-doped porous silica nanomaterials by utilizing the combination of nickel, iridium, and ruthenium metal slats in order to explore them as potential catalysts for electrochemical water oxidation process. We present a simple strategy to synthesize multi-metal-doped silica materials with spherical morphology, deploying a cation surfactant template (CTAB) as a structure directing agent in water-ethanol solvent mixtures. These materials are thoroughly characterized with the help of powder X-ray diffraction (PXRD), UV–Vis, FT-IR, X-ray photoelectron spectroscopy (XPS), high resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscopy (FE-SEM), nitrogen-sorption isotherm, thermogravimetric (TGA) analysis. The particles are 550–600 nm in size with a fine-looking spherical morphology and surface area in the range of 111–419 m2/g. Among all of these metal-silica, Ni–Ir–Ru-doped mesoporous silica particles (NIRS) exhibit excellent electrocatalytic activity towards oxygen evolution reaction (100 mA/cm2 current density@0.5V) with long-term durability up to 10 h, and the Tafel slope is also very low (∼68 mV/dec) in 1 M KOH medium. The excellent electrical conductivity of Ni–Ir–Ru-doped silica makes it a superior electrocatalyst due to its spherical morphology, synergistic effects of the multi metallic components, and its hierarchical nanoporous structure. [Display omitted] • A facile method for multi-metal-doped mesoporous silica was developed. • The particle sizes were 550–600 nm and surface area were up to 419 m2/g. • Multi-metal-doped mesoporous silica particles were spherical particles. • NIRS generated 100 mA/cm2 and current density@0.5V during OER in pH=14. • NIRS exhibited high durability up to 10 h with Tafel slope of 68 mV/dec in pH=14. [ABSTRACT FROM AUTHOR]

Constructing bifunctional electrocatalysts is essential for efficient water splitting. Rational interface engineering is an effective method for modifying active sites and promoting electronic charge transfer, resulting in improved water splitting efficiency. In this study, we designed a metal-free, 2D structure of graphene and boron nitride (h-BN). 2D stacking of two different layers generated abundant interfaces as well as huge electrochemical active sites. As a result, the graphene/h-BN stacked structure has a very low overpotential of 28 mV (for 10 mA/cm2 current density) for hydrogen evolution. At the same time, a significantly low overpotential of 360 mV (for 50 mA/cm2 current density) was achieved for oxygen evolution. The stacked structure of graphene/h-BN has been effectively utilized as a promising cathode and anode in a two-electrode system for accomplishing overall water splitting. Thus, our investigation suggests that rational construction of heterogeneous interfaces by stacking different 2D nanostructures can accelerate the overall water splitting by maximizing the electrochemical performance. [Display omitted] • Graphene layer was engineered by stacking h-BN • 2D stacking generated abundant interfaces as well as huge electrochemical active sites • A very low overpotential of 28 mV (for 10 mA/cm2 current density) for hydrogen evolution • Overpotential for OER was significantly low 360 mV (for 50 mA/cm2 current density) [ABSTRACT FROM AUTHOR]

In electrocatalytic water decomposition technology, particularly in alkaline solutions, hydrogen evolution with transition metal catalysts has received significant interest. In this study, an efficient HER electrocatalyst with nickel foam base was produced by electrodeposition. Compared with other catalysts, the synthesized CoMo@EDTA electrocatalyst showed significant electrocatalytic activity against HER in alkaline electrolytes. By changing the type of complexing agent, it is found that the overpotential is the lowest after adding EDTA-2Na in 1 mol/l NaOH solution. The overpotential of the CoMo@EDTA catalyst is 29 mV, When the current density is −10 mA/cm2, The outstanding HER performance of CoMo@EDTA electrocatalysts is mainly due to the interaction of molybdenum and cobalt and the effect of complexing agents. After the stability measurement for up to 6 h, the catalyst has a minimal overpotential loss, indicating that the catalyst has excellent stability. This work provides a useful pathway for the application of transition metals in hydrogen evolution electrocatalysts. [Display omitted] • The catalyst preparation steps are simple and the time is short (40 min). • The prepared catalyst has low overpotential (29 mV) and low tafel slope. • The prepared catalyst has the characteristics of strong stability (6 h without obvious overpotential loss). • We analyzed the effects of different complexing agents on the catalyst and found that EDTA-2Na had the best effect. [ABSTRACT FROM AUTHOR]

Designing an ideal bi-functional electrocatalyst for the overall water splitting plays significant function in alternative energy construction. Based on the previous literatures, the Co 3 O 4 /g-C 3 N 4 nanocomposite has been investigated as the bi-functional electrocatalyst. In the present study, the facile hydrothermal route was approached to synthesize the Co 3 O 4 /g-C 3 N 4 nanocomposite to enhance the electrocatalytic activity towards oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Further, Co 3 O 4 /g-C 3 N 4 electrochemical analysis was undergone in an aqueous alkaline solution of 1 M potassium hydroxide for both OER and HER. High electrocatalytic nature of prepared Co 3 O 4 /g-C 3 N 4 nanocomposite delivered the low 170 mV overpotential value and 151 mV at 20 mA/cm2 with Tafel values 188 mV/dec and 176 mV/dec for OER and HER. Also electrochemical surface area (ECSA) of prepared Co 3 O 4 /g-C 3 N 4 nanocomposite was estimated from double layer capacitance (C dl) values, and calculated ECSA values are 0.027 cm2 and 0.097 cm2 for OER and HER respectively. The resultant Co 3 O 4 /g-C 3 N 4 nanocomposite reached the low charge transfer resistance value of 15.9 Ω for OER and 22.7 Ω for HER which could acts as strong parameter to improve conductivity of the prepared electrode for both half reactions. Along with that, stability of Co 3 O 4 /g-C 3 N 4 nanocomposite exhibits the outstanding performance at the current density of 10 mA/cm2 with only minimum amount of loss even after 16 h for both OER and HER. Hence, the synthesized Co 3 O 4 /g-C 3 N 4 nanocomposite was act as an optimistic choice of the bi-functional electro catalyst for sustainable energy production. • Attempted Co 3 O 4 /g-C 3 N 4 for bi-functional electrochemical water splitting. • Co 3 O 4 /g-C 3 N 4 delivered 170 and 151 mV at 20 mA/cm2 with low Tafel values 188 and 176 mV/dec for OER and HER. • Stability of Co 3 O 4 /g-C 3 N 4 for long duration up to 16 h results 74% and 60% retention for both OER and HER. • Co 3 O 4 /g-C 3 N 4 was optimistic choice of the bi-functional electrocatalyst. [ABSTRACT FROM AUTHOR]