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Developing new forms of flexible zinc–air (Zn–air) batteries is crucial to economic growth. Nevertheless, the absence of an oxygen evolution reaction catalyst with high catalytic efficiency and low-cost causes instability of Zn–air battery cycling and economic unviability, respectively. In this paper, a leaf-like N-doped carbon structure with CoS2 nanoparticles self-supported on carbon fiber paper (CoS2-CZ@CFP) was developed as an air electrode for Zn–air batteries, which not only uses nonprecious metal elements, but also has a self-supporting configuration, enhancing the contact between the catalyst and electrode while facilitating the transfer of electrons. Sulfur as the source gas was introduced into Co-doped metal–organic skeletons (Co-ZIFs) anchored on carbon fiber paper (CFP) for in situ vulcanizing transition metal Co, which successfully ensures the uniform distribution of sulfide particles in the carbon matrix, hence enriching active catalyst sites. The CoS2-CZ@CFP demonstrated an overpotential of 1.611 V at J = 50 mA cm−2, superior to RuO2@CFP (1.814 V). A Zn–air battery fabricated using the synthesized CoS2-CZ@CFP exhibited an extended life cycle of 117 h. This research paves the way for a novel method of designing self-supporting configurations of sulfides and carbon matrix composites as promising air electrodes applicable to Zn–air batteries. [ABSTRACT FROM AUTHOR]

It is significant to develop low-cost and highly efficient electrocatalysts for the hydrogen evolution reaction (HER) via electrochemical water splitting. Herein, we constructed P-doped NiCo2S4 nanowire arrays on carbon fiber paper (NiCo2S4−xPx/CFP) as a HER electrocatalyst in both acidic and alkaline media. Benefitting from P doping into NiCo2S4, the as-prepared NiCo2S4−xPx/CFP exhibits low HER overpotentials of 80 and 132 mV in acidic and alkaline media at a cathodic current density of 10 mA cm−2, respectively, which are far superior to counterparts of NiCo2S4 nanowire arrays on the carbon fiber paper (NiCo2S4/CFP). Meanwhile, the NiCo2S4−xPx/CFP presents excellent HER stability of 20 hours in acidic and alkaline media. From the results of density functional theory calculations, P doping can not only optimize the hydrogen adsorption energetics on each kind of atomic site of catalysts, but also strengthen the H2O molecule binding ability on the catalyst surface for the alkaline HER and favor kinetics of hydrogen adsorption and H2 formation on the catalyst surface for the acidic HER, eventually improving overall HER performances. The investigation of the HER mechanism modulated by P doping in our work offers novel inspiration to develop highly efficient ternary metal sulfides for the HER. [ABSTRACT FROM AUTHOR]

A well-designed support material between catalyst and substrate can always significantly enhance the performance of an electrode on water oxidation. In this work, a functional Ni and N-doped carbon layer (NNC) was designed on carbon paper (CP) via pyrolysis by using a controlled electrodeposited polyporphyrin as a precursor. Consequently, the fabricated NiFe-LDH/NNC/CP achieved a catalytic current density of 100 mA cm−2 at a small overpotential of 231 mV with a low Tafel slope of 26.0 mV dec−1, as well as high durability for more than 360 h. The insights are that N-doping reinforces the hydrophilicity and the catalyst binding capacity, while Ni-doping intensifies the conductivity. [ABSTRACT FROM AUTHOR]

Searching and developing earth-abundant electrocatalysts with predominant activity and favorable stability are significant to resolve increasing environmental pollution and serious energy crisis. In this paper, Mo-based nanowire arrays (NWAs) were synthesized on carbon fiber paper (CFP), and then Ru–MoP NWAs/CFP was successfully assembled through impregnation of Ru and phosphorization. The as-obtained Ru–MoP NWAs/CFP exhibited excellent performance over a broad pH range. As a result, overpotentials of 39.0, 49.9, and 67.1 mV were required to reach the current density of 10 mA cm−2 in 0.5 M H2SO4, 1 M KOH, and 1 M PBS, respectively. The outstanding performance of Ru–MoP NWAs/CFP is mainly related to the introduction of Ru and P atoms, which may enhance the conductivity of the catalyst and develop additional HER active sites. Our work may afford a novel designing approach to develop high performance HER electrocatalysts. [ABSTRACT FROM AUTHOR]

Exploring Earth-abundant and efficient electrocatalysts to replace Ir and Ru for the acidic oxygen evolution reaction (OER) is essential to reduce the cost of clean hydrogen production. Here, we show that trace amounts of electronegative non-metallic element fluorine (F)-doped Co3O4 nanoneedles improve the activity and stability of Co3O4. The F-doped Co3O4 nanoneedles supported on carbon paper (F-Co3O4/CP) exhibit an overpotential of 350 mV at 10 mA cm-2 for the acidic OER. In addition, their performance remains consistent after continuous operation for 80 h. Detailed investigations reveal that introducing an anion promotes the enrichment of OH on the surface of Co3O4 and prevents acid corrosion, thereby enhancing the intrinsic OER activity and stability. Theoretical calculations further indicate that F doping can effectively improve electron transfer and optimize the energy barrier for the formation of *OOH intermediates, which significantly improves OER performance. This study provides guidance for designing efficient and stable non-noble metal acidic water oxidation catalysts. [ABSTRACT FROM AUTHOR]

High entropy materials (HEM) have been attracting much attention as emerging catalysts for electrochemical water splitting. HEM catalysts have unique properties such as an interesting cocktail effect, broad design space, customizable electronic structure, and excellent entropy stabilization effect compared with single-digit catalysts. This paper provides a comprehensive overview of the use of HEM as a catalyst for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and water splitting. HEM design strategies including phase structure modulation, defect engineering, electrode configuration engineering, and computational aids are discussed to develop HEM catalysts with high performance and stability. In particular, the importance of density functional theory, high-throughput screening techniques, and machine learning for the discovery and design of HEM catalysts is emphasized. Finally, the challenges and imminent difficulties are prospected, and the corresponding strategies to deal with these challenges are put forward to promote the development of HEM catalysts in the field of electrochemical water splitting. [ABSTRACT FROM AUTHOR]

As one of the effective methods for hydrogen production, water electrolysis has been widely studied. However, the high overpotential challenge faced by the anode and the limitation of the electron transfer rate in this process significantly inhibit the efficiency of hydrogen production, which has become the main obstacle to overcome in the current research. The use of thermodynamically more favorable organic compounds to oxidize at the anode instead of traditional water oxidation (OER) is an effective strategy to optimize the process of electrolytic hydrogen production. In this paper, Ni3S2 catalysts co-doped with non-noble metals Li and Mn were prepared on nickel foam and used for the glycerol oxidation reaction (GOR) coupled with the hydrogen evolution reaction (HER). In alkaline solution, Li, Mn–Ni3S2@NF exhibits good GOR and HER performance. Specifically, overpotentials of 1.58 V vs. RHE and 0.54 V vs. RHE are required to reach a current density of 200 mA cm−2, respectively, and the catalytic performance of the material remains good after a long-term test. Li, Mn–Ni3S2@NF as a bifunctional catalytic material oxidizes glycerol to formate, and its faradaic efficiency (FE) is as high as 91%, and the volume of hydrogen production is close to the theoretical value. In addition, the replacement of the OER by the GOR can reduce the energy consumption by about 17.44%. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. The issue includes various articles and papers on topics such as organic charge transfer complexes, metal organic frameworks, mechanical properties of cocrystals, and scintillation crystals. The journal is published by The Royal Society of Chemistry, a leading chemistry community that reinvests its profits back into the chemistry community. [Extracted from the article]

Platinum-based catalysts exhibit outstanding electrocatalytic performance in the hydrogen evolution reaction (HER). However, platinum-based catalysts face significant challenges due to their rarity and high cost. This paper endeavors to shed light on a promising alternative: polyoxometalate (POM)-based catalysts, which possess significant potential for the synthesis of non-noble metal-based catalysts for the HER. Utilizing POMs as raw materials to assemble POM-derived materials, including POM-derived crystalline materials, metal sulfides, phosphides, carbides, nitrides, and so on, has emerged as an effective approach for the synthesis of hydrogen evolution electrocatalysts. This approach offers advantages in both stability and electrocatalytic performance. This comprehensive review navigates through latest progress in the assembly strategy and HER performance of POM-based crystal materials, alongside discussion on transition metal compounds derived from POMs, such as carbides, phosphides, and sulfides. Besides, future developments in POM-derived electrocatalyst regulation of the electrochemical HER are prospected. [ABSTRACT FROM AUTHOR]

Hybrid water electrolysis (HWE) is a promising pathway for the simultaneous production of high-value chemicals and clean H2 fuel. Unlike conventional electrochemical water splitting, which relies on the oxygen evolution reaction (OER), HWE involves the anodic oxidation reaction (AOR). The AORs facilitate the conversion of organic or inorganic compounds at the anode into valuable chemicals, while the cathode carries out the hydrogen evolution reaction (HER) to produce H2. Recent literature has witnessed a surge in papers investigating various AORs with organic and inorganic substrates using a series of transition metal-based catalysts. Over the past two decades, metal–organic frameworks (MOFs) have garnered significant attention for their exceptional performance in electrochemical water splitting. These catalysts possess distinct attributes such as highly porous architectures, customizable morphologies, open facets, high electrochemical surface areas, improved electron transport, and accessible catalytic sites. While MOFs have demonstrated efficiency in electrochemical water splitting, their application in hybrid water electrolysis has only recently been explored. In recent years, a series of articles have been published; yet there is no comprehensive article summarizing MOFs for hybrid water electrolysis. This article aims to fill this gap by delving into the recent progress in MOFs specifically tailored for hybrid water electrolysis. In this article, we systematically discuss the structure–property–performance relationships of various MOFs utilized in hybrid water electrolysis, supported by pioneering examples. We explore how the structure, morphology, and electronic properties of MOFs impact their performance in hybrid water electrolysis, with particular emphasis on value-added chemical generation, H2 production, potential improvement, conversion efficiency, selectivity, faradaic efficiency, and their potential for industrial-scale applications. Furthermore, we address future advancements and challenges in this field, providing insights into the prospects and challenges associated with the continued development and deployment of MOFs for hybrid water electrolysis. [ABSTRACT FROM AUTHOR]

In this paper, we provide a novel electrode switch (ES) method to improve the stability of the alkaline electrolyzer toward water splitting. The voltage of the alkaline electrolyzer consisting of commercial Ni mesh electrodes utilizing the ES mode exhibits extreme stability because highly active Ni oxide(hydroxide) with oxygen defects is in situ formed during the hydrogen evolution reaction (HER) polarization process. [ABSTRACT FROM AUTHOR]

The New Journal of Chemistry is a publication that features articles and papers on various topics in chemistry. The current issue includes papers on lithium-sulfur batteries, graphene, and carbon nanotubes, among others. The journal is published by The Royal Society of Chemistry and the Centre National de la Recherche Scientifique. The papers provide valuable insights and findings in their respective fields of research, covering topics such as compound synthesis, crystal structures, magnetic behavior, and the development of new materials for applications like photocatalysis and electrocatalysis. The journal also offers professional recognition and development opportunities for scientists. [Extracted from the article]

The New Journal of Chemistry, published by the Royal Society of Chemistry, features articles on a wide range of topics in chemistry. The current issue covers subjects such as nanosized metals, liquid catalyzed growth of graphene, and photocatalytic CO2 reduction. The journal aims to provide innovative and cutting-edge reports that have a strong chemical component and broad appeal. This document is a compilation of research papers from the journal, covering topics such as electrocatalysts, nanocomposites, halogenation reactions, supramolecular assembly, and more. The papers explore various applications, including agriculture and waste digestion. [Extracted from the article]

Electrocatalytic water splitting is considered to be one of the most promising technologies for large-scale sustained production of H2. Developing non-noble metal-based electrocatalytic materials with low cost, high activity and long life is the key to electrolysis of water. Transition metal sulfides (TMSs) with good electrical conductivity and a tunable electronic structure are potential candidates that are expected to replace noble metal electrocatalysts. In addition, self-supported electrodes have fast electron transfer and mass transport, resulting in enhanced kinetics and stability. In this paper, TMS self-supported electrocatalysts are taken as examples and their recent progress as hydrogen evolution reaction (HER) electrocatalysts is reviewed. The HER mechanism is first introduced. Then, based on optimizing the active sites, electrical conductivity, electronic structure and adsorption/dissociation energies of water and intermediates of the electrocatalysts, the article focuses on summarizing five modulation strategies to improve the activity and stability of TMS self-supported electrode electrocatalysts in recent years. Finally, the challenges and opportunities for the future development of TMS self-supported electrodes in the field of electrocatalytic water splitting are presented. [ABSTRACT FROM AUTHOR]

The use of a methanesulfonic acid (MSA) electrolytic system is recommended as a green method for hydrometallurgical recovery of metallic Pb from waste lead-acid batteries (LABs), contributing to the sustainable protection of the ecosystem. Nevertheless, the system's high energy consumption is a current issue due to the substantial overpotential of the oxygen evolution reaction (OER) and competitive anodic oxidation of Pb2+. Herein, we propose an IrFe/nitrogen-doped pyrolytic carbon black (IrFe/NCBp) composite as a novel OER catalyst for the MSA electrolytic system, which demonstrates advanced OER catalytic efficiency and selectivity for H2O oxidation. This can be ascribed to the catalyst's thoughtful design, which enhances the number and uniformity of Ir and Fe species via increasing the specific surface area and employing NCBp as a sustainable substrate. The optimized IrFe/NCBp composite exhibits superior OER performance, with a low 252 mV@10 mA cm−2 overpotential and a 62 mV dec−1 Tafel slope, and excellent durability in a 1 M MSA electrolyte for 30 h operation compared to commercial Ir/C. In contrast to carbon paper (CP) and commercial Ir/C anodes, the anodic reaction of IrFe/NCBp is primarily OER-driven (97%) in 1 M MSA and 0.2 M Pb2+ electrolyte for Pb recovery. This effectively circumvents the high potential oxidation of Pb2+ into PbO2, reducing the electrolytic voltage to 488 kWh for the recovery of 1 ton Pb metal. This work provides a green, low-carbon footprint solution for the MSA electrolytic system, thereby promoting the commercialization of the hydrometallurgical Pb recovery. [ABSTRACT FROM AUTHOR]

In this paper, a novel Pt/CoP/C photo-electro synergistic catalyst was successfully synthesized by a hydrothermal method combined with phosphorus doping treatment. The addition of Vulcan XC-72R is in favor of effectively preventing agglomeration of active catalytic sites, resulting in more uniform and smaller Pt and CoP nanoparticles. The as-obtained Pt/CoP/C shows excellent photo-electro catalytic performance for the HER with simulated solar light irradiation. The optimal hydrogen production is 5384.18 mmol h−1 g−1, which is obviously higher than that of the commercial catalyst (20 wt% Pt/C: 4608.52 mmol h−1 g−1). The research results show that introducing cobalt phosphide into the Pt catalyst can improve the electrocatalytic activity and stability for the HER; in particular, the existence of Co3O4 in Pt/CoP/C leads to an efficient photo-electro catalysis under irradiation, which significantly improves the catalytic activity of Pt. The results above provide a novel strategy for the rational design of cost-effective Pt-based composites towards a fast HER. [ABSTRACT FROM AUTHOR]

Bimetallic two-dimensional (2D) metal–organic framework (MOF) materials display excellent electrocatalytic performance due to the synergistic effect between metals and the advantage of the 2D structure. In this work, Cu was introduced into the 2D Co-MOF structure, and a 2D book-like CuCo-MOF structure was fixed on carbon fiber paper (CFP) for direct electrochemical glucose detection and oxygen evolution reaction (OER). The materials showed good electrocatalytic glucose detection performance with a sensitivity as high as 6.861 mA mM−1 cm−2 and a detection limit as low as 0.12 μM. For the OER, when the current density is 10 mA cm−2, the overpotential (η) is 340 mV, and good stability is maintained for about 10 h without current attenuation. This work not only exploits a new 2D MOF structure containing Cu, but also expands the potential of Cu-containing MOF materials in the electrocatalytic OER, making a contribution to the field of energy conversion and biomolecular sensing. [ABSTRACT FROM AUTHOR]

The urea oxidation reaction (UOR), which possesses a low theoretical potential and superior kinetics, is an attractive substitute for the anodic oxygen evolution reaction (OER) in overall water splitting; however, the implementation of hydrogen production in overall urea splitting is impeded by the deficiency of highly efficient, durable and cost-effective catalysts. Herein, we fabricated an Ni2P–MoP2 heterostructure with a hierarchical structure grown on carbon paper (Ni–Mo–P/CP), which exhibited robust activity and outstanding durability for the electrocatalytic oxidation of urea. The Ni–Mo–P/CP catalyst possessed an ultralow potential of 1.39 V to obtain the current density of 100 mA cm−2, small Tafel slope (27 mV dec−1) and long-term durability with almost no decay within 15 h. The experimental characterization revealed that the optimized electronic structure and the synergistic effect of abundant exposed active sites in the Ni–Mo–P/CP catalyst contribute to the efficient UOR catalytic activity. This work enriches the candidate catalysts for the UOR and promotes the industrial development of hydrogen production. [ABSTRACT FROM AUTHOR]

Nowadays, the goal of carbon peaking and carbon neutrality has become a global consensus, and electrochemical CO2 reduction to provide high-value power fuel is one of the major technical approaches attracting significant research interests and application prospects. However, the inevitable hydrogen evolution reaction in water-based electrolyte systems crowds out the reactive sites of active metals, causing a low CO2 conversion efficiency. In this work, Zn nanosheets were prepared via electrodeposition on the surface of carbon paper and then modified with polytetrafluoroethylene (PTFE) to tune the wetting angle of the electrolyte. A CO faradaic efficiency of 90.2% was achieved for Zn NS-8% PTFE (contact angle: 136.8°) at the electrolytic voltage of −1.0 V vs. RHE along with an overall current density of −7.9 mA cm−2. Experimental results and molecular dynamics simulation revealed that PTFE weakened the aggregation of H2O molecules and was more beneficial for capturing and adsorbing CO2 molecules near the electrode surface. The active sites of hydrogen production were transformed into the reaction center for electrocatalytic CO2 reduction due to the hydrophobicity of the electrode, and the accumulation of the local CO2 concentration accelerated the kinetic activity for electrochemical conversion (CO2 to CO). This strategy of tuning the local environment offers an alternative approach for effective electrode manufacturing in liquid electrolytes. [ABSTRACT FROM AUTHOR]

Developing high-efficiency electrocatalysts for the hydrogen evolution reaction (HER) is of great importance. In this paper, dendrite-free Ni–Cu catalysts were synthesised via one-step pulse electrodeposition under a weak magnetic field (0.5 T). Regardless of the direction of the magnetic field, the ions were affected by the magnetohydrodynamic (MHD) effect, which greatly promoted the mass transfer and dispersion uniformity, and suppressed the uncontrollable agglomeration by electrodeposition. It was found that the nucleation mechanism changed from progressive nucleation under a 0 T magnetic field to instantaneous nucleation under a 0.5 T magnetic field. Large-scale (325 nm, 0 T) dendrite growth on the single-sided plane was successfully suppressed, and replaced by smaller (90 nm, 0.5 T) and uniformly distributed cluster growth around the carbon paper. In addition, the (111) plane was strengthened by the magnetic field. Electrochemical analysis showed that the Ni–Cu catalysts exposed more surface area and exhibited greatly enhanced catalytic activity, which only needed −57.3 mV to deliver the current density of 10 mA cm−2 with a small Tafel slope of 99.4 mV dec−1 in 1 M KOH. Overall, magneto-electrodeposition, especially under weak magnetic field conditions, provides great promise for the preparation of HER catalysts. [ABSTRACT FROM AUTHOR]

Benefiting from a high overpotential of the competitive hydrogen evolution reaction with a carbon paper cathode, the desired electrochemical reduction of imines was achieved with high faradaic efficiency by using H2O as a H-source. With this sustainable atom-economic strategy, a series of potentially versatile amines were obtained in medium-to-high yields (49–86%). [ABSTRACT FROM AUTHOR]

Here, polyaniline (PANI) is reported loaded on carbon paper to modify the carbon paper-PANI-Pt electrode surface, tailoring the electrocatalytic capability towards the hydrogen evolution reaction and ethanol oxidation reaction. The reasons for the enhancement by the PANI layer are attributed to the hydrophilic electrode surface, uniform dispersion of Pt, and large electrochemical active surface. [ABSTRACT FROM AUTHOR]

Rational design and controllable synthesis of transition metal multi-anionic structures to cooperatively catalyze the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) remain a great challenge due to the requirements of high current density and long-term durability for water splitting. Herein, a self-supported sheet-on-sheet hierarchical interface was synthesized via a facile corrosion engineering strategy, where the Ni3S2 microsheet arrays were pre-grown on nickel foam and they provided abundant surface active sites to grow FeOOH nanosheets vertically. The obtained FeOOH/Ni3S2 heterostructure exhibited well-defined dimensions and intimate interface contact with oxygen and a sulfur anion structure, which can modulate the electronic structure of interfacial active sites. Hence, the optimized FeOOH/Ni3S2 required overpotentials of 345 mV and 269 mV to achieve a current density of 100 mA cm−2 for the HER and the OER, respectively. Moreover, it required a voltage of 1.855 V to achieve overall water splitting at a current density of 100 mA cm−2. The interfacial electronic interaction and multi-anionic hierarchical structure not only facilitate the electron transfer between the FeOOH/Ni3S2 surface and intermediate species but also accelerate the kinetic rate. This paper provides a new avenue to design multi-anionic hierarchical structures as cost-effective and highly stable electrocatalysts for practical overall water splitting. [ABSTRACT FROM AUTHOR]

The shortage of freshwater resources in the world today has limited the development of water splitting, and our eyes have turned to the abundant seawater. The development of relatively low-toxicity and high-efficiency catalysts is the most important area in seawater electrolysis. In this paper, the preparation of NiS2@Co4S3@FeS via a hydrothermal method on nickel foam has been studied for the first time. In the process of vulcanization, Fe will first generate FeS by virtue of its high affinity for vulcanization. Once Fe is vulcanized, the residual sulfur will be used to generate NiS2, while the vulcanization of Co requires a higher sulfur concentration and reaction temperature; thus, Co4S3 will be generated last. NiS2@Co4S3@FeS is confirmed to have excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) catalytic properties in alkaline seawater. Its unique structure allows it to expose more reaction centres, and the synergies between the multiple metals optimize the charge distribution of the material and accelerate the OER and HER kinetics. NiS2@Co4S3@FeS requires overpotentials of only 122 mV and 68 mV for the OER and HER when reaching 10 mA cm−2, which is superior to most catalysts reported to date for seawater electrolysis, and the material displays acceptable stability. In an electrolytic cell composed of both positive and negative electrodes, when the current density is 10 mA cm−2, the NiS2@Co4S3@FeS material displays a low overpotential of only 357 mV for seawater splitting. Density functional theory shows that the FeS electrode has the optimum Gibbs free energy of H to accelerate reaction kinetics, and the synergistic catalysis of the NiS2, Co4S3 and FeS materials promotes the hydrogen production activity of the NiS2@Co4S3@FeS electrode. This work proposes a novel idea for designing environmentally friendly seawater splitting catalysts. [ABSTRACT FROM AUTHOR]

Efficient alkaline hydrogen evolution electrodes must be used for hydrogen production in anion exchange membrane water electrolyzers (AEMWEs). Therefore, we fabricated a NiMnS catalyst with a Mn-rich surface, which was self-supported on Ti paper through one-step electrodeposition. Mn doping endowed the catalyst with a unique hollow morphology and lattice-distorted structure. Consequently, the NiMnS/Ti electrode exhibited a large number of exposed electrochemical surfaces and effective active sites and a high hydrogen evolution reaction (HER) activity. Specifically, in half-cell measurements, the NiMnS/Ti electrode exhibited an overpotential of 65 mV at 10 mA cm−2, which was lower than that of NiS/Ti (102 mV) and indicated its superior HER activity. When the proposed cathode was applied in an AEMWE single cell, the device achieved a high current density of up to 0.9 A cm−2 at a cell potential of 2.0 V. [ABSTRACT FROM AUTHOR]

Urea electrolysis can be used to treat wastewater containing urea and alleviate the energy crisis, so it is one of the best ways to solve environmental and energy problems. This paper reports the synthesis of M doped NiVS (M = Co, Ce and Cr) composites by a simple hydrothermal process for the first time. What is noteworthy is that the Ce-NiVS material as a catalytic electrode requires only 141 mV overpotential for the hydrogen evolution reaction (HER) and 1.291 V potential for the urea oxidation reaction (UOR) at a current density of 10 mA cm−2 in 1.0 M KOH and 0.5 M urea mixed alkaline solution. Using Ce-NiVS/NF as both the anode and cathode for urea electrolysis, a current density of 10 mA cm−2 is driven by a voltage of only 1.55 V, which is better than most previous catalysts. Experimental results demonstrate that the excellent catalytic activity of Ce-NiVS materials is due to the formation of a large number of active sites and the improvement of conductivity due to doping with Ce. Density functional theory calculation shows that the VS4 material has a small Gibbs free energy of hydrogen adsorption, which plays a major role in the hydrogen production process, and Ce-NiS has a higher density of states (DOS) near the Fermi level, indicating that Ce-NiS has better electronic conductivity. The synergistic catalysis of VS4 and Ce-NiS promoted the hydrogen production performance of the Ce-NiVS material. This work provides guidance for the optimization and design of low-cost electrocatalysts to replace expensive precious metal-based electrocatalysts for overall urea electrolysis. [ABSTRACT FROM AUTHOR]

The development of a bifunctional ruthenium-based electrocatalyst that can efficiently and economically drive both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) remains challenging because ruthenium species can undergo severe agglomeration during preparation which can significantly reduce the catalytic activity. Constructing supported metal catalysts can not only improve the stability of Ru but also improve the catalytic performance by adjusting the electronic structure, which is an effective way to solve the current challenges. In this paper, Ru-loaded MoO2/MoO3 heterostructures (Ru–MoOx) with oxygen vacancies were successfully synthesized by controlling the annealing temperature. This special structure can effectively tune the electronic structure, enhance the electrical conductivity and increase the active sites, thus improving the catalytic activity of the catalyst. Performance studies have shown that Ru–MoOx exhibits excellent HER and OER performance in alkaline media. And it is not surprising that the overall water decomposition performance of Ru–MoOx is also excellent, requiring only a cell voltage of 1.54 V to reach 10 mA cm−2. [ABSTRACT FROM AUTHOR]

Improving the efficiency of the anodic oxygen evolution reaction (OER) is important to solve the global energy crisis and greenhouse gas emission problems. In this paper, a preparation method for a MIL-53(Fe)@ZIF-67(Co) composite electrode is proposed. The hierarchical structure formed by the combination of MIL-53(Fe) and ZIF-67(Co) provides a rich channel for the transport of electrons and mass in the OER process. XPS analysis and DFT calculations revealed that Fe electrons in MIL-53(Fe) were transferred to Co in ZIF-67(Co) through O, which confirmed the rapid charge transfer effect of this transport channel. The MIL-53(Fe)@ZIF-67(Co) electrode has significant OER performance. When the current density reaches 10 mA cm−2, the overpotential is only 193 mV. This study inaugurates a new way for the rational design of a multiphase interface and the construction of new MOF channel structures. [ABSTRACT FROM AUTHOR]

The development of high-performance and cost-effective electrocatalysts for the oxygen evolution reaction (OER) is critical to renewable energy conversion and storage technologies. Among of them, metal organic frameworks (MOFs) have been proved to be effective substitutes for precious metals. In this paper, a series of mixed NiCoFe-MOFs with low crystallinity were synthesized by a simple one-step solvothermal method, which can be used as a direct electrocatalyst for the OER. Notably, the flower-like nanocatalyst NiCoFe-MOF-2 exhibits a hierarchical pore network and a large specific surface area (149.6 m2 g−1), which results in an adjustable electronic structure, effective mass transfer, and abundant exposed active sites. In addition, due to the synergy between the three metals Fe, Co and Ni, NiCoFe-MOF-2 can exhibit excellent electrocatalytic OER performance, with a low overpotential of 321 mV at 10 mA cm−2, superior to commercial RuO2 (379 mV), a Tafel slope of 48 mV dec−1 and long-term stability. The result may stimulate more designs of MOF-derived catalysts with multi-scale structures and multi-components designed for various electrochemical energy conversion devices. [ABSTRACT FROM AUTHOR]

The development of noble-metal-free electrocatalysts with high catalytic efficiency, low cost, and high durability in pH-universal media is encountering a bottleneck in practical applications. In this paper, Ni@MoN-700 coral hybrids were prepared using hydrogen evolution reaction (HER) catalysts, which were synthesized by a high-temperature reduction of NiMoO4 nanorods with urea. It was found that the annealing temperature seriously affects the surface morphology and chemical composition of the catalysts. Besides, structural reorganization occurred during the HER, which involved the joining of pyrrolic N, metal nitrogen, Mo3+, and Mo6+, governing the HER performance. Also, during the HER, Ni and Mo could synergistically improve the overall catalytic activity of the catalysts, via electronic interactions. These advantages endow Ni@MoN-700 with exceptional endurance and great HER activity, with a low overpotential of 30 mV and 76 mV at 10 mA cm−2 in alkaline and acidic media. These characteristics are similar to those of Pt under alkaline conditions. NiMoN catalysts show unusual activity and long-term stability, indicating a wide range of potential applications. [ABSTRACT FROM AUTHOR]

In this paper, a series of micro–nano reactors assembled by N doped carbon coated TiO2 heterojunction nanosheets with different thickness, named TiO2/N–C hollow framework (HF), TiO2/N–C hollow hexahedron assembled by nanosheets (HHS), and TiO2/N–C hollow hexahedron assembled by ultrathin nanosheets (HHUS), have been prepared by adjusting the alcoholysis rate of NH2-MIL-125 and then pyrolysis. Experimental and theoretical studies revealed that with the decrease of the thickness of the heterojunction nanosheet subunit, more low-coordination Ti atoms would be exposed as effective sites for photocatalytic H2 evolution, and the interaction between the carbon layer and TiO2 would also be enhanced, which provided a smooth migration path for the effective separation of photogenerated carriers. Thus, TiO2/N–C HHUS with the thinnest nanosheet subunit exhibited the best photoelectric performance and the highest photocatalytic hydrogen production activity. [ABSTRACT FROM AUTHOR]

Designing a robust bifunctional water splitting catalyst at low cost is of great importance for water splitting. Herein, the in situ-generated MoS2/NiS2 nanosheet heterostructures by cobalt incorporation on carbon paper (Co–MoS2/NiS2/CP) are first obtained by applying a scalable chemical vapor vulcanization approach. Based on the synergistic effects of cobalt element doping and the construction of MoS2/NiS2 heterostructures, the much enhanced electrocatalytic performance for full water electrolysis is clearly revealed. In particular, the electronic structure of MoS2/NiS2 heterostructures was further effectively modified by cobalt incorporation along with the electron density of catalytic sites, which both promote the Volmer step to speed up alkaline hydrogen evolution reaction (HER) and optimize the oxygen-containing intermediate adsorption to enhance oxygen evolution reaction (OER). Consequently, Co–MoS2/NiS2/CP heterostructures presented low overpotentials (HER: η10 = 109 mV; OER: η10 = 323 mV) in the basic solution. Furthermore, Co–MoS2/NiS2/CP was designed as a two-electrode alkaline electrolytic configuration for full water electrolysis. This strategy experimentally illustrates the feasibility of designing a conventional electrocatalyst for water electrolysis via the cooperative effects of metal doping and heterostructured engineering. [ABSTRACT FROM AUTHOR]

In recent years, as a green renewable energy production technology, electrochemical water splitting has demonstrated high development potential. Many materials have been reported as successful catalysts in the water-splitting field. However, it is still a huge challenge to produce bifunctional electrocatalysts for the efficient and sustainable generation of hydrogen and oxygen simultaneously. Herein, we successfully developed oxygen vacancies abundant CuCo layered double oxide (Ov-CuCo-LDO) hollow nanotube arrays (HNTAs) loaded on nickel foam as advanced electrocatalysts for total water splitting. When the current density was 10 mA cm−2, the Ov-CuCo-LDO HNTAs exhibited outstanding onset overpotentials of 53.9 and 72.5 mV for the hydrogen evolution and oxygen evolution reactions (HER and OER) in alkaline medium, respectively, because of the bimetallic synergistic effect between the cobalt and copper and the unique hollow porous structure. In addition, an as-assembled Ov-CuCo-LDO‖‖Ov-CuCo-LDO electrolytic cell showed a small potential of 1.55 V to deliver a current density of 10 mA cm−2. Moreover, it also showed remarkable durability after long-term overall water splitting for more than 20 h. The research results in this paper are of great interest to practical applications of the water decomposition process, providing clear and in-depth insights into preliminary robust and efficient multifunctional electrocatalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

In this paper, NiCo2S4 was coated on the surface of WS2 of a 1T/2H mixed phase by a two-step hydrothermal method to form an in situ core–shell structure. The unique S-scheme heterojunction of the NiCo2S4@WS2 core–shell composite photocatalyst improved the easy recombination of carriers caused by the narrow band gap of NiCo2S4 and WS2, and improved the photocatalytic hydrogen production performance. The loading ratio of NiCo2S4@WS2, the addition of Eosin Y, and the pH value of TEOA were optimized. Under the optimal conditions, the hydrogen production rate reached 5.814 mmol g−1 h−1, which is about 8.55 times and 3.35 times the hydrogen evolution rates of NiCo2S4 and WS2, respectively. The composite catalyst exhibits excellent charge separation efficiency in photoelectrochemistry, PL and BET tests, carrier transport rate and large specific surface area that can provide more active sites, which are the main factors for the improvement of the hydrogen evolution performance. This paper demonstrates new design strategies to drive efficient photocatalytic hydrogen production by building in situ core–shell structures and optimizing the carrier transport paths, which will yield new insights. [ABSTRACT FROM AUTHOR]

In this paper, the structural characteristics and catalytic mechanism for hydrogen evolution of ammonia borane of non-metal (N, S) doped CoP catalysts were studied in detail by density functional theory (DFT) calculations. Specifically, we first investigated the structure of the cobalt phosphide catalyzed ammonia borane models. In addition, based on the most stable structures, the mechanism of the hydrogen evolution reaction of ammonia borane catalyzed by three catalysts was studied, and four feasible reaction paths for the hydrogen evolution reaction of ammonia borane catalyzed by three catalysts were discussed. By comparing the activation energies of the control steps of different reaction paths, the optimal reaction paths for the hydrogen evolution of ammonia borane catalyzed by three different catalysts were determined. The catalytic activities of the three catalysts for the hydrogen evolution of ammonia borane were compared. We found that the N-doped catalyst was beneficial to improve the catalytic activity of CoP for the catalytic hydrogen evolution of ammonia borane, while the catalytic activity of S-doped CoP for the catalytic hydrogen evolution of ammonia borane is relatively weak. These results reveal the relationship between the physical properties of CoP (and its non-metal-doped variants) and their catalytic activity. Finally, these findings can be used to explain the underlying mechanism reported in previous experimental studies from a microscopic perspective. [ABSTRACT FROM AUTHOR]

Cocatalysts are usually applied in the photocatalytic water splitting process to accelerate the kinetics of the hydrogen evolution reaction (HER). Specifically, the transition metal nitride (Mo2N) featuring a unique local surface plasmon resonance (LSPR) effect has exhibited great potential to function as a HER cocatalyst. However, the low metallicity of Mo2N hampers its ability to improve charge separation. To address this issue, transition metal atom doping (Co and Cu) engineering was used to modulate the electronic structure of Mo2N nanosheets to achieve a higher electrical conductivity and a lower hydrogen adsorption free energy (‖ΔGH*‖), thereby favoring the HER kinetics. Density functional theory (DFT) calculations and experimental results showed that Co-doping and Cu-doping mainly take place at Mo sites in the crystal structure of Mo2N to form stable structures of Co doped Mo2N (Co–Mo2N) and Cu doped Mo2N (Cu–Mo2N). Compared with pristine Mo2N, both Cu–Mo2N and Co–Mo2N demonstrated a much improved cocatalytic effect over g-C3N4 in promoting charge separation, accelerating HER kinetics and enhancing light absorption. The Co–Mo2N with the highest conductivity and lowest ‖ΔGH*‖ illustrated the best cocatalytic effect, and the H2 production performance (367.8 μmol g−1 h−1) of Co–Mo2N/g-C3N4 achieved was 10 and 5 times higher than those of Mo2N/g-C3N4 and Cu–Mo2N/g-C3N4. This paper provides significant guidance in the design and development of efficient cocatalysts for the HER application. [ABSTRACT FROM AUTHOR]

Hydrogen (H2) is a new type of renewable energy that can meet people's growing energy needs and is environmentally friendly. In order to improve the industrial application prospects and electrochemical performance of hydrogen evolution catalysts, extensive research on transition metal materials has been carried out. Among the many catalytic materials, cobalt is an element with potential for the hydrogen evolution reaction (HER) due to its abundant reserves, low cost, and small energy barrier for H adsorption. This review classifies the latest research on cobalt-based catalysts according to the types of compound, including cobalt-based sulfides, phosphides, carbides, borides, oxides, etc., and summarizes the latest research progress of cobalt-based compound catalysts in acidic and alkaline media. Strategies to tune the properties of cobalt-based compound catalysts for high catalytic activity for HER are focused on, including structural engineering, defect engineering, and doping, etc. The advantages and limitations of each modified approach are reviewed. Not only that, but also the catalytic activity and advantages of the catalyst are evaluated by using density functional theory (DFT) calculation-related descriptors, activity evaluation parameters, etc. Finally, limitations and challenges of cobalt-based materials for HER are presented, as well as prospects for future research. This paper aims to understand the chemical and physical factors that affect cobalt-based catalysts, and to find directions for future research on cobalt-based catalysts. [ABSTRACT FROM AUTHOR]

Increasing fossil fuel demands and growing concerns of global climate change have stimulated interest in the development of electrocatalysts to produce H2 as an alternative zero-emission fuel from the electrolysis of water via hydrogen evolution reaction (HER). Precious or non-precious catalysts are typically loaded on high surface area carbon materials, and these supports play a critical role in both thermodynamics and kinetics of the HER. In this paper, we evaluate the electrocatalytic activity of a molecular hydrogen evolving catalyst, diacetyl-bis(4-methyl)-3-thiosemicarbazone Ni(II) (Ni-ATSM), on three different carbon surfaces: glassy carbon, carbon paste and pencil graphite. The overpotential for each modified electrode was benchmarked at a current density of −10 mA cm−2. Carbon paste electrodes showed highest overpotentials (495 mV) compared to the other electrode surfaces. Polished pencil and glassy carbon modified electrodes performed similarly (η = 395 mV for GCE and η = 400 mV for pencil). Pencil electrodes etched in acetone overnight prior to Ni-ATSM deposition produced lowest overpotentials (η = 354 mV). Etching results in an increase in electroactive surface area and substantial decrease in the charge transfer resistance of the graphitic interface from 275 Ω to 50 Ω, verified using electrochemical impedance spectroscopy (EIS). Our studies demonstrate pencil graphite may serve as versatile, disposable, cost effective, and reproducible electrode surface for the evaluation of heterogeneous HER catalysts. Moreover, pencils can be easily cut with table saw to generate new surface for easy characterization of the surface such as electrochemistry, imaging and spectroscopy. [ABSTRACT FROM AUTHOR]

Constructing a suitable heterojunction structure while maintaining a tight interface to promote the separation of photogenerated electrons is of great significance for improving the photocatalytic activity. In this paper, a new PANI/NH2-MIL-101(Fe) II-scheme heterojunction was prepared by a hydrothermal method. PANI with a porous structure was firstly obtained by the template method, and then PANI fragments were loaded on the surface of NH2-MIL-101(Fe) crystals under hydrothermal conditions to obtain a PANI/NH2-MIL-101(Fe) photocatalyst. The photocatalytic degradation of TC under simulated sunlight can reach 90% within an hour, and the maximum hydrogen evolution rate is 7040 μmol g−1 h−1 under visible light. The enhanced catalytic performance of PANI/NH2-MIL-101(Fe) was attributed to the appropriate matching of the VB and CB of PANI and NH2-MIL-101(Fe), and secondly, the coordination bonds formed between PANI and NH2-MIL-101(Fe) provided a channel for charge separation and transfer. Finally, a possible mechanism of the photocatalytic system was proposed through a free radical capture experiment and characterization analysis. More importantly, the experiment proved that the heterojunction formed by PANI and NH2-MIL-101(Fe) can achieve the effect of complementing each other, which provides a feasible idea and method for the design of efficient heterojunction photocatalysts. [ABSTRACT FROM AUTHOR]

Compared with the noble metal Pt, the non-noble metal Cu as a cocatalyst exhibits a low hydrogen-evolution activity owing to its weak Cu–H bond (11 kcal mol−1), which inhibits hydrogen adsorption on Cu atoms for the hydrogen-evolution reaction of photocatalysts. Considering that the introduction of Ni with a strong Ni–H bond into Cu is beneficial for strengthening the H-adsorption ability of Cu, in this paper, the low-cost transition-metal Ni was directly introduced into Cu to form CuNi alloy nanodots as photocatalytic cocatalysts to enhance the hydrogen-evolution rate of TiO2. The CuNi alloy nanodots (2–3 nm) were photodeposited on the surface of a reduced graphene oxide (rGO)-modified TiO2 photocatalyst to generate CuNi-rGO/TiO2 by the pre-adsorption of Cu2+ and Ni2+ ions on graphene oxide (GO). Photocatalytic hydrogen-production data manifested that the CuNi-rGO/TiO2 photocatalyst achieved the highest hydrogen-production rate (10 411 μmol h−1 g−1), which was 53.7, 38.7, 1.8, and 2.2 times higher than that of pure TiO2, rGO/TiO2, Cu-rGO/TiO2, and Ni-rGO/TiO2, respectively. Density-functional-theory (DFT) calculations and mechanistic investigation showed that the introduction of Ni into Cu to form CuNi alloy nanodots improved the H-adsorption ability of Cu and optimized the H-adsorption free energy close to zero (0.046 eV) for boosting the hydrogen production rate of TiO2. This research presents a promising design of bimetallic alloy structures as H2-production cocatalysts for efficient photocatalysts. [ABSTRACT FROM AUTHOR]

FeCo2O4 is a potential OER catalyst, but its catalytic activity still needs to be further improved due to its poor electrical conductivity and low material utilization. In this paper, we construct oxygen-vacancy-rich two dimensional FeCo2O4 nanosheet materials using a liquid-phase reduction strategy. Benefiting from its large specific surface area, numerous surface catalytic sites, enhanced electrical conductivity, and modulated electronic structure, the catalyst exhibits an overpotential of only 270 mV at a current density of 10 mA cm−2, which is lower than that of the original FeCo2O4 nanosheets (420 mV). At the same time, the catalyst can run steadily for 20 hours without obvious decay. [ABSTRACT FROM AUTHOR]

Lithium is thought to be an excellent anode material for next-generation Li metal batteries (LMBs). However, some problems with lithium anodes often lead to serious safety concerns and catastrophic failures due to the huge volume change, Li dendritic growth, and related side reactions. Therefore, in order to manufacture stable rechargeable batteries, the abovementioned serious problems must be effectively solved. In this paper, a three-dimensional N,P-doped silicon-containing lithium anode is designed and prepared by in situ metallurgy using low-cost Si3N4. The 3D stable composite anode (DLi/LiSix CA) was prepared by adding a small amount of Si3N4 to molten lithium to form N-doped silicon-containing lithium metal which was supported on a polyaniline modified carbon cloth (PMCC). The results show that the DLi/LiSix CA not only has high Li affinity but can also effectively inhibit lithium nucleation and lithium dendritic growth, so as to maintain good structural stability in the process of Li plating/stripping. The new lithium metal anode based on doping and 3D carbon cloth shows good cycling stability and low polarizability in both symmetrical and full cells. [ABSTRACT FROM AUTHOR]

Transition metal nitrides have good metallic conductivity and high pseudocapacitance, which have drawn extensive attention in the research of Zn-ion energy storage systems. In this paper, we present a novel fabrication of carbon cloth-supported TiN-coated carbon nanotube composites (TiN/CNTs@CC and TWC) via a CVD–ALD method using ethanol, TiCl4 and H2O as precursors. The prepared TWC composites can be used as self-supported electrodes with good flexibility and conductivity. Electrochemical performance tests show that the TiN/CNTs@CC electrode has a high specific capacitance of 363.5 F g−1 at 0.5 A g−1, good rate capability and excellent cycling stability with 92.9% capacity retention over 10 000 charge/discharge cycles. Impressively, the assembled zinc ion hybrid capacitor can achieve a high energy density of up to 81.8 W h kg−1 at a power density of 137.7 W kg−1. Even at a power density of 3013.7 W kg−1, a high energy density of 26.4 W h kg−1 is still achieved. This study provides a new insight into the application of nitride-derived carbon materials in zinc-ion hybrid capacitors. [ABSTRACT FROM AUTHOR]

The rational design of high-efficiency electrocatalysts for application in water oxidation in alkaline media remains a great challenge. In this paper, Ni3+-rich nanograss-like Mo-doped Ni3S2/NiS/VS arrays grown on nickel foam (denoted as Mo-NiVS@NF) have been successfully constructed through a hydro/solvothermal method. Interestingly, Mo-NiVS@NF exhibits superior catalytic OER performance, needing an overpotential of 217 mV to drive a current density of 10 mA cm−2, outperforming most previously reported NiS-based electrocatalysts. The result indicates that the Ni3+-rich active sites caused by the modulation of the electronic structure environment via the introduction of V and high-valency Mo play an important role in the high activity for the OER. Moreover, this catalyst shows high long-term electrochemical durability. [ABSTRACT FROM AUTHOR]

Water electrolysis is one of the most promising approaches for producing hydrogen. However, the OER, kinetics are sluggish and necessitate highly efficient electrocatalysts to speed up the reaction. In this work, we used NiCo glycerate solid nanospheres as a precursor to construct Fe–Ni–Co trimetallic oxide nanospheres utilizing a solvothermal-annealing and stirring technique. The oxygen evolution reaction (OER) activity of the Fe–Ni–Co spheres was greatly enhanced after Fe doping. Among these samples, the FeNiCo-15 hierarchical yolk–shell spheres needed overpotentials of only 204 and 178 mV for the OER and HER, respectively, to drive a current density of 10 mA cm−2, and showed good electrochemical stability. Further, it also presented superior electrocatalytic activity in terms of full water splitting, which was comparable to the integrated performance of the Pt‖IrO2 couple. A cell voltage of only 1.61 V was required to attain a current density of 10 mA cm−2. This paper provides a promising method for developing efficient bifunctional electrocatalysts driving redox electrocatalysis. [ABSTRACT FROM AUTHOR]

Hydrogen energy is a promising energy source that is environmentally friendly due to its long-term, large-capacity storage and low greenhouse gas emissions. However, the mass production of hydrogen is still technically difficult due to limitations in efficiency, stability, and cost, even though it can satisfy all of the current energy demands. Water splitting using an electrocatalyst is an efficient method for environmentally friendly hydrogen production, and various catalyst-related studies are being conducted for this purpose. For the last decade, transition metal-based compositions have been at the center of water splitting catalyst research. Despite numerous studies and developments, studies on transition metal-based catalysts so far still have various problems to be solved. Although excellent review papers on transition metal-based catalysts have been reported, the overall scope of transition metal-based catalysts has rarely been covered in the reports. In this review, we present the research about overall transition metal-based electrocatalysts for hydrogen production from four different categories, namely, alloys, transition-metal dichalcogenides (TMDs), layered double hydroxides (LDHs), and single-atom catalysts (SACs). The fundamental roles of metal alloying and unique electrical properties of TMDs, LDHs, and SACs are mainly discussed. Furthermore, we present the recent advances in photovoltaic–electrochemical (PV–EC) systems for sustainable hydrogen production. Finally, perspectives on the issues to be addressed in the research on transition metal-based electrocatalysts are provided. [ABSTRACT FROM AUTHOR]

In this paper, we present a MoP/P–Mn0.5Cd0.5S photocatalytic material (PMOMCS-Px). A novel catalyst can efficiently split water into hydrogen without precious metals. In the sacrificial agent environment, the HER (hydrogen evolution rate) of PMOMCS-P5 was 4368.25 μmol g−1 h−1 which was 11.4 times greater than the HER of Mn0.5Cd0.5S (383.19 μmol g−1 h−1), and its hydrogen production performance was better than that of Pt/Mn0.5Cd0.5S (2.0 wt% Pt). Furthermore, the hydrogen evolution performance of PMOMCS-P5 under pure water conditions was also examined, and the HER of PMOMCS-P5 was 209.76 μmol g−1 h−1, which was 20.4 times that of Mn0.5Cd0.5S (10.29 μmol g−1 h−1). Its characterization proved that the introduction of the co-catalyst MoP and P doping inhibited the recombination of e− and h+, enhanced the reduction capacity, and reduced the hydrogen precipitation reaction overpotential of PMOMCS-Px, thus enhancing the hydrogen production performance of PMOMCS-Px. Therefore, an efficient and economical photocatalyst was prepared. [ABSTRACT FROM AUTHOR]

Due to the slow reaction kinetics of the oxygen evolution reaction (OER), the electrolysis rate of water is greatly limited. Therefore, it is of great significance to study stable and efficient non-noble metal based electrocatalysts. In this paper, three-dimensional (3D) spherical V-NiFe LDH@Ni3S2 was developed by exquisitely decorating ultra-thin V-doped NiFe layered dihydroxide (NiFe-LDH) on Ni3S2 nanosheets supported by nickel foam (NF). It is worth mentioning that V-NiFe LDH@Ni3S2 exhibits an excellent electrocatalytic performance and only 178 mV overpotential is required in 1 M KOH to achieve a current density of 10 mA cm−2. Long-term chronoamperometry manifests its superior electrochemical stability. The combination of NiFe LDH and conductive substrate coupling can drastically afford abundant active sites and accelerate charge transfer, and V doping can markedly regulate the electronic structure. Therefore, the activity and durability of the electrocatalysts are greatly improved. This study may provide a new strategy for the preparation of efficient OER electrocatalysts. [ABSTRACT FROM AUTHOR]

In contrast to irregular polycrystals, the orderly structure and the clear surface atomic termination layer of porous single crystals demonstrate unique physical and chemical properties, including excellent electrical conductivity, an extremely large specific surface area, a small grain boundary area and low interfacial resistance. This could provide sufficient well-defined active sites for improving the catalytic activity and stability. Here, we grow well-shaped porous single-crystalline vanadium nitride octahedra and irregular porous polycrystalline vanadium nitride from non-porous NH4V4O10 single-crystal precursors. These well-shaped porous single-crystalline materials show a superior hydrogen evolution reaction (HER) performance. When used as HER catalysts, the overpotential of the VN porous single crystal is only 74.67 mV at a current density of 10 mA cm−2. By contrast, the overpotential of the irregular VN porous polycrystal is 150.66 mV under the same experimental conditions, which demonstrates the unique nature of the porous single-crystalline octahedron material. In contrast to traditional irregular polycrystals, this paper inspires the construction of porous single-crystalline materials with a crystal structure of long-range order of in the micron range for significantly improving the electrocatalytic performance. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the electro-catalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of synthesized copper tungsten oxide@reduced graphene oxide (CuWO4@rGO) nanocomposites. The prepared CuWO4@rGO nanocomposites show bifunctional electro-chemical performances for the HER and OER via water splitting reactions in alkaline (0.5 M KOH) and acidic (0.5 M H2SO4) media. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) reveal superlative HER and OER performances of the CuWO4@rGO nanocomposites. The onset over-potentials of the CuWO4@rGO nanocomposites were found to be ∼270 and ∼330 mV for the OER in 0.5 M KOH and 0.5 M H2SO4, respectively, while the onset potentials were found to be ∼180 and ∼135 mV for the HER in 0.5 M KOH and 0.5 M H2SO4, respectively. The CuWO4@rGO nanocomposites also showed lower Tafel slopes of ∼110 and ∼315 mV dec−1 for the OER in 0.5 M KOH and 0.5 M H2SO4, respectively, while the Tafel slopes of the CuWO4@rGO nanocomposites were found to be ∼192 and ∼212 mV dec−1 for the HER in 0.5 M KOH and 0.5 M H2SO4, respectively. Hence, the small energy loss of low-cost electro-catalysts during electro-chemical water splitting reactions reveals comparable HER/OER performances with noble electro-catalysts. [ABSTRACT FROM AUTHOR]