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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]

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]

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]

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]

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]

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]

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, 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]

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]

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]

Developing low-cost high-efficient electrocatalysts for alkaline hydrogen evolution reaction (HER) is of critical significance in hydrogen production via alkaline electrolyzers. Herein, we prepared CeO2/Co4N heterostructure for the catalyst in alkaline HER, which introduced a synergistic effect within the CeO2 and Co4N catalytic sites that facilitates the two consecutive steps in alkaline HER reaction. More importantly, plasma treatment was further applied to the material to tune the electronic structure of the catalytic sites by creating multiple anion vacancies. The introduced O vacancies accelerated the H2O cleaving process on CeO2, while the N vacancies in Co4N optimized the H adsorption strength on the Co sites. The catalytic activity of the catalyst improved significantly after plasma treatment. It only required an overpotential of 36 mV@10 mA cm−2 for the HER operated in 1 M KOH electrolyte and provided one of the best precious metal-free catalysts ever reported. [ABSTRACT FROM AUTHOR]

The efficient production of hydrogen through water electrolysis requires stable, high-performance and rather cost-effective electrocatalysts to promote the hydrogen evolution reaction (HER). Platinum (Pt) is known to be a benchmark electrocatalyst for the HER, but its high-cost is a major obstacle for large-scale applications. Therefore, reducing Pt loading on electrodes, with a minimal influence on the electrochemical performance is of significant importance. Here, we report on the effective utilization of Pt through a simple two-step magneto-electrodeposition synthesis method, leading to the formation of uniformly dispersed Pt/NiCu electrocatalysts with an excellent catalytic activity. Under optimum conditions, NiCu substrates are fabricated under a vertical static magnetic field of 0.5 T, followed by pulsed electrodeposition of Pt under the same magnetic field. The electrocatalyst (0.5 T NiCu + 0.5 T Pt) exhibits a high stability and superior HER activity, characterized by low overpotentials of 10.6, 54.6, and 87.8 mV obtained at current densities of 10, 100, and 200 mA cm−2, respectively, accompanied by a small Tafel slope of 13.4 mV dec−1 in alkaline media (1 M KOH). This work provides a new approach enabling the optimum utilization of Pt-based electrocatalysts employed for the HER. [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]

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]

The quest for efficient, cost-effective non-platinum catalysts for the hydrogen evolution reaction (HER) is critical to reduce energy losses in alkaline electrolyzers. NiCrO/MCu111 (M = Mn, Fe, Co and Ni) interface sites were designed to investigate the HER activity trend by the PAW-PBE method. The synergy effect between oxide and transition metals modulated the H2O adsorption activation and reduced the H2O dissociation energy barrier to around 0.12 eV. The BEP relationship between Ea and ΔEH* was established for H2O dissociation. The H2O adsorption and dissociation properties on NiMO/Cu111(M = Cr, Mn, Fe and Co) were investigated. NiCrO/Cu111 exhibited a better HER activity than NiMO/Cu111 (M = Mn, Fe and Co). The relationship between the energy barriers (Ea) and the reaction energies (ΔE) was elucidated through the BEP relationship, highlighting the influence of oxide's electronic effects on the activity. This work demonstrates an engineering strategy to design oxide/metal interface sites with a low-cost multimetallic composition and with tuned electronic structures to achieve excellent HER activity. [ABSTRACT FROM AUTHOR]

A new strategy for doping selenium and phosphide in hollow N-doped carbon nanobox (N-CNB)-based porous electrospun N-doped carbon nanofibers (CNFs) was developed. First, lightweight N-CNBs were produced. Then, a hybrid of N-CNBs and CNFs (CNBs/CNFs) was prepared using electrospinning/carbonization techniques. Eventually, P and Se atoms were doped into CNBs/CNFs using a thermal treatment approach to prepare Se/P@CNBs/CNFs. The electrocatalytic capability of the Se/P@CNBs/CNFs composite toward H2O2 oxidation was investigated for H2O2 sensing, which showed performance in a linear range from 200 μM to 1800 μM with a high sensitivity of 171 μA mM−1 cm−2 and a limit of detection (LOD) of 58 μM (S/N = 3). In addition, the ability of Se/P@CNBs/CNFs toward H2O2 sensing in human serum was studied. These results indicated the excellent electrocatalytic performance of the as-prepared Se/P@CNBs/CNFs, which could be related to the unique hollow CNBs/CNFs doped with P and Se elements with a mesoporous structure, the open channels for effective H2O2 diffusion, fast mass/electron transport, and synergistic effect between the P and Se and CNBs/CNFs. [ABSTRACT FROM AUTHOR]

Direct methanol fuel cells (DMFC) are a promising new energy source. However, the lack of high-performance and low-cost methanol oxidation electrocatalysts hinders their commercial application. Firstly, we successfully prepared NENU-5-derived molybdenum carbide material (Cu-MoC) via a co-precipitation and high-temperature carbonization method using a material composed of a copper-based metal–organic skeleton and a molybdenum-based carbide as the main body. Secondly, PtCu nano-alloy catalysts (Pt/Cu-MoC) were prepared using a unique, spontaneous single replacement reaction after metal–organic skeleton (MOF) carbonization. Through the synergistic effect between Pt and Cu and the strong interaction between Mo2C and PtCu, the electronic structure of the Pt is modified, the energy of the d-band center is reduced, electron exchange is accelerated, and catalytic activity is enhanced. Compared with a commercial Pt/C catalyst in alkaline environments, the Pt0.10/Cu-MoC catalyst has a better MOR catalytic activity (563.25 mA mgPt−1), which is 1.5 times higher than that of commercial Pt/C (376.67 mA mgPt−1). The Pt0.10/Cu-MoC catalyst has an onset potential for CO oxidation that is 16 mV lower than that of commercial Pt/C, indicating better resistance to CO poisoning. Exploring carbon materials derived from MOFs with excellent junction support and using them as carriers to prepare Pt-based catalysts is a practical and feasible approach. It provides a way to develop new Pt-based catalysts that perform efficient MOR. [ABSTRACT FROM AUTHOR]

Water electrolysis is considered the most promising technology for hydrogen production. In the present study, RCoFe (regulated cobalt ferricyanide) is synthesized via the co-precipitation method, which is characterized by physical and electrochemical properties. XRD confirmed the crystalline phase of RCoFe and the diffraction peaks are consistent with JCPDS#82-2284. FE-SEM examines the nanoplatelet morphology, which could help with the mass transfer of electrons during the electrochemical process. Here, RCoFe promotes the extensive activity for the OER (oxygen evolution reaction) with 270 mV/GC; 252 mV/NF at 10 mA cm−2. The lower Tafel value for RCoFe (78 mV dec−1/GC; 107 mV dec−1/NF) was derived from LSV when compared to IrO2 (98 mV dec−1/GC; 123 mV dec−1/NF) and stable for a long time with minimal loss of potential (130 h/GC-1.5%; 250 h/NF-1.8%) owing to citrus sap, which stabilized the electrocatalyst. After electrochemical treatment, the post-SEM morphology reveals that the nanoplatelets are completely bound together to enhance the OER process. [ABSTRACT FROM AUTHOR]

Hollow structures with a hierarchical architecture and multi-composition have attracted extensive interest because of their fascinating physicochemical properties as well as wide applications. To improve the efficiency of overall water splitting, highly active and stable electrocatalysts are highly desirable. A novel high-efficiency oxygen defect based hierarchical hollow nanosheet-based-nanosphere Co–NiMoO4-HNS electrocatalyst for oxygen evolution was arranged by doping Co on a Ni-MoEG yolk/shell nanosphere. Co–NiMoO4-HNS has a greater hydrophilicity and smaller band gap than that of NiMoO4-CS. Post OER characterization indicates that the main active phase of the Co2–NiMoO4-HNS catalysts toward the OER are amorphous Ni3+, Co3+, and H–O and the high-valent Mo (+6) can make nickel and cobalt better maintain Ni3+ and Co3+ sites. Remarkably, this hierarchical hollow Co2–NiMoO4-HNS catalyst exhibits a favorable catalytic performance toward the oxygen evolution reaction (OER) with a receivable overpotential of 270 mV achieving a current density of 10 mA cm−2 and a Tafel slope of 65 mV dec−1. In expansion, as an electrocatalyst, Co2–NiMo4-HNS appeared to have a great long-term steadiness in the electrolyte. This work may give a broad hypothetical and specialized background for plans of cost-effective bifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal sulfides possess high intrinsic catalytic activity for the oxygen evolution reaction (OER) during water splitting but are restricted by their low conductivity and unattractive stability in alkaline electrolytes. Herein, newly designed CoS2/MoS2 nanosheets with enriched heterointerfaces synthesized by the combination of hydrothermal and vulcanization methods showed great promise as a highly efficient OER electrocatalyst. Owing to the fast vulcanization process, some heterometallic sulfide nanoparticles get distributed on the nanosheets, thus forming a nanoparticle-nanosheet bridging structure. The rich heterogeneous interface between CoS2 and MoS2 regulates the electronic structure and provides sufficient electrochemical active sites, thus forming a fast channel conducive to electron transport and ensuring high OER activity. Besides, the rough heterostructured surface enhances hydrophilicity, which promotes the decomposition of H2O and decreases the energy barrier of intermediate reactions, leading to fast electrochemical kinetics. Benefiting from the structural merits, the optimized CoS2/MoS2-1 : 1 nanosheets exhibit a low overpotential of 283 mV at 10 mA cm−2, a small Tafel slope of 105.32 mV dec−1 and long-term durability for the OER. [ABSTRACT FROM AUTHOR]

The application of non-noble metal catalysts to photocatalytic hydrogen production from water holds a high practical application value. In this study, photocatalysts were obtained by the hydrothermal and photodeposition methods. The optimal photocatalytic hydrogen production from water decomposition was 2641 μmol g−1 h−1. The results showed that compared with traditional composites, a ZnCdS(Two-Step)/Ni photocatalyst synthesized with Prussian blue analogue (PBA) as the precursor shows better photocatalytic performance for hydrogen evolution. Moreover, the introduction of Ni is found to be a feasible strategy to modulate the performance of photocatalysts, providing a reference for the construction of materials with excellent photocatalytic properties. [ABSTRACT FROM AUTHOR]

Molybdenum phosphide (MoP) is recognized as one of the most promising catalysts for the hydrogen evolution reaction (HER); however the low electronic conductivity and complicated synthesis process still restrict its commercialization as a replacement for the benchmark Pt/C catalyst. Herein, a novel type of MoP nanoparticles encapsulated with biomolecule-derived N, P-codoped carbon nanosheets has been successfully fabricated by a simple one-step pyrolysis of ammonium molybdate tetrahydrate, 1-hydroxyethylidene diphosphonic acid (HEDP) and a unique biomolecule guanine as the precursor of two-dimensional carbon materials. Benefiting from the well-designed architecture with both good electronic conductivity and easily accessible catalytic sites provided by the 2D carbon structure, the optimized catalyst exhibits synergistically enhanced HER activity under both alkaline and acidic conditions, especially with a low overpotential of 104 mV to deliver 10 mA cm−2 in 1 M KOH. Moreover, the coverage of N, P-codoped graphene-like carbon layers can prevent the corrosion of MoP nanoparticles in harsh reaction media, ensuring superior durability. This work has opened up a new direction for further development of simple, low-cost but efficient novel electrocatalysts. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOF) were used as templates to prepare transition metal sulfides and phosphides in order to expose the active site of the material to a greater extent. Utilizing the synergistic effect of bimetals, Ni2+ and Mo6+ were selected as metal ion centers and trimesic acid was selected as the ligand to prepare NiMo-MOFs by the hydrothermal method. Then, NiMo-P, NiMo-S and NiMo-P/S were prepared using NiMo-MOFs as the precursor, and the preparation conditions of the abovementioned hybrids were optimized through linear sweep voltammetry. The results show that when the molar ratio of NiMo-MOF to NaH2PO2 is 1: 5, and the as-prepared NiMo-P is further doped with S in a proportion of 1: 1, the overpotential of the final NiMo-P/S hybrid is 313 mV at a current density of 10 mA cm-2, and its electrochemical impedance (Rct), Tafel slope and electrochemical active surface areas are 22.38 Ω, 63.8 mV dec-1, and 707.5 cm-2, respectively. The optimized NiMo-P/S hybrid provides more active sites and reaction areas along with good stability, which is conducive to promoting the kinetics of the oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

Recently, many studies have been done on MXene (2D titanium carbide) for energy storage applications. It possesses outstanding features like hydrophobicity, conductivity, and particularly strong surface redox reactivity, which are essential for energy storage applications. Despite these exceptional properties, MXene's electrochemical performance is significantly impacted by certain deficiencies, such as the inability to assemble MXene sheets. To prevent MXene sheets from restacking, the spaces between them must be filled with an appropriate material. Metal-organic frameworks (MOFs) for electrochemical applications have also been extensively studied. Due to their high crystallinity, porous structure, and substantial surface area, MOFs find diverse applications, but their efficacy as electrode materials is hindered by a lower specific capacity and charging/discharging rate. Addressing these limitations, combining MOFs with suitable materials is preferred for enhanced performance. This study suggests an innovative approach: a composite between Cu-BTC MOF and N-MXene. By shortening both the ion/electron diffusion pathways and improving the electroactive sites, the prevention of MXene sheet restacking was achieved, leading to exceptional specific and rate capacity in the composite with MOFs. The Cu-BTC/N-MXene-decorated electrode exhibited energy and power density reaching approximately 65.23 W h kg-1 and 923 W kg-1 in a two-electrode (real device) configuration. Cu-BTC/N-MXene//N-MXene retained 99% of its capacity and a coulombic efficiency of 92% after 8000 alternate GCD cycles. The findings of this investigation highlight the significant potential of employing the innovative electrode material Cu-BTC/N-MXene for supercapattery applications. [ABSTRACT FROM AUTHOR]

Medium entropy alloys, consisting of four elements in close to isotropic proportions, have attracted a great deal of attention because of their unique properties (excellent strength, corrosion resistance, etc.). Here, we present a series of quaternary medium entropy alloy FeCoNiW electrocatalysts loaded onto nitrogen-doped carbon (NC) skeletons. The prepared medium entropy alloy catalysts have excellent OER catalytic activity and stability. In alkaline media, the FeCoNiW-NC electrocatalysts annealed at 350 °C were able to achieve an overpotential as low as 225 mV at a current density of 10 mA cm−2, which is 55 mV lower than that of the commercial RuO2, while it has a smaller Tafel slope of 54 mV dec−1. The introduction of W leads to a change in the electronic structure of the FeCoNi alloy and increases the specific surface area of the catalyst, exhibiting excellent performance. This work contributes to the exploration of OER catalysts by opening new avenues for the design of efficient and economical OER electrocatalysts. [ABSTRACT FROM AUTHOR]

Cellulose nanofiber (CNF) is an environmentally friendly material with a high specific surface area, which is an ideal candidate for cathode catalysts in zinc–air batteries (ZABs). However, untreated CNF-based carbon materials suffer from low intrinsic activity and fewer micro-mesopores. Herein, we developed an N-doped porous carbon aerogel from CNF and graphite phase carbon nitride (g-C3N4) via hydrothermal pretreatment and the carbonization process. The CNF can serve as the skeleton of the aerogel that leads to an interconnected porous structure, while g-C3N4 guarantees the in situ N doping and the formation of more nanopores. Therefore, the as-prepared carbon aerogel exhibits excellent oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performances owing to the successful N doping with sufficient graphite-N and pyridine-N active sites (69.1%) and high specific surface areas (785.4 m2 g−1). The assembled ZABs with a carbon aerogel deliver a specific capacity of 790 mA h g−1 and an energy density of 945.6 W h kg−1 with a long-term stability over 100 h. This work opens a new avenue for the effective conversion of abundant biomass into bifunctional air cathodes for energy-related applications. [ABSTRACT FROM AUTHOR]

MoSe2 as one graphene-like 2D transition metal selenide has attracted great attention. However, its application for the hydrogen evolution reaction (HER) is still restricted by the poor electrical conductivity and structural restacking. In this work, an excellent electrocatalyst for hydrogen production is developed based on the in situ synthesis of V-doped MoSe2 confined on carbon black nanoparticles (denoted as V-MoSe2/CB) via a sol–gel process. The characterization results show that the carbon black nanoparticles can protect the V-MoSe2 nanosheets from agglomeration, resulting in ultra-thin thickness and short vertical lattice arrays. Meanwhile, density functional theory (DFT) calculations indicate that vanadium doping can optimize the electronic structure of MoSe2. Accordingly, compared to the pure MoSe2, V-MoSe2 and MoSe2/CB electrocatalysts, V-MoSe2/CB exhibits improved electrocatalytic activity with a small overpotential of 166 mV at −10 mA cm−2 and a small Tafel slope of 65 mV dec−1. This work paves a new way for improving the HER performance through synergistic morphology, structure and electronic regulation. [ABSTRACT FROM AUTHOR]

Porphyrins have been widely used in designing photocatalyst systems. However, finding an effective strategy to improve the intrinsic photocatalytic activity of porphyrin molecules remains a challenge. Here, two new porphyrins, meso-tetra(5-carboxyfuryl)porphyrin (H2TCFP) and meso-tetra(5-carboxythienyl)porphyrin (H2TCTP), were successfully synthesized and compared with meso-tetra(m-carboxyphenyl)porphyrin (H2TmCPP), to clarify the influence of the organic unit bridging the carboxyl acid group with the porphine ring on the photocatalytic activity of porphyrin for H2 evolution from water splitting. The H2 evolution rates of 10.8 mmol g−1 h−1 observed for H2TCFP and 9.7 mmol g−1 h−1 for H2TCTP are both larger than 8.0 mmol g−1 h−1 observed for H2TmCTP under optimal conditions. The best photocatalytic activity observed for H2TCFP was investigated through experiments and density functional theory (DFT) calculations and was interpreted in terms of the combined effect of several key factors of the entire photocatalytic process, including the high absorptivity of UV light, high separation efficiency of photogenerated carriers, and low Gibbs energy required for associated water splitting. Meanwhile, the concentration-dependent performance of photocatalytic activity was analyzed and attributed to the aggregation and light-bleaching effect exerted on porphyrins. [ABSTRACT FROM AUTHOR]

Subphthalocyanines (SubPcs) have emerged as promising organic dyes for the development of efficient artificial photosynthetic devices, offering intense absorption in the visible region along with excellent charge transport properties. In this study, four novel SubPc derivatives containing carboxylic acid and various peripheral substituents were synthesized as a panchromatic photosensitizer to prepare an efficient and stable TiO2-based photocatalytic system for co-catalyst-free photocatalytic hydrogen evolution. To compare the influence of the nature of the peripheral substituents on photocatalytic activity, SubPc derivatives (coded as SubPc 1–4) were decorated with substituents having different electron-donating capabilities, such as alkyl thio, benzodioxin, amine, and iodo units, respectively. Photocatalytic activities were examined in the presence of TEOA as a sacrificial agent under irradiation with λ > 400 nm without co-catalyst loading. SubPc 1/TiO2 shows the best photocatalytic activity among the SubPc-sensitized photocatalysts, with a hydrogen evolution rate of 0.176 mmol h−1. While the activity of all four SubPc-based photocatalysts increased significantly after 24 h irradiation, notably, SubPc 1/TiO2 exhibited remarkable catalytic activity, achieving a hydrogen evolution rate of 6.017 mmol with a high turnover number (TON) value of 12 279 for hydrogen production. This study highlights the potential of SubPc-based sensitizers for co-catalyst-free photocatalytic H2 production and offers valuable insights into the impact of peripheral units in SubPc/TiO2-based photocatalytic systems. [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]

The electrochemical reduction of NO2− to NH3 provides a promising approach for both the treatment of harmful NO2− and the sustainable production of NH3. In this study, a low-coordinated Pd metallene (L-Pd) was first explored as an efficient NO2RR electrocatalyst, showing an exceptional FENH3 value of 95.2% and a high NH3 yield rate of 511.5 μmol h−1 cm−2. A combination of experimental and computational studies revealed that the significantly enhanced NO2RR performance of L-Pd originates from the low-coordinated Pd sites for boosting NO2− activation and decreasing the energy barrier of the *NO → *NHO rate-determining step while suppressing the competing hydrogen evolution. [ABSTRACT FROM AUTHOR]

The utilization of cost-effective and excellent precious metal-free catalysts for the hydrogen evolution reaction (HER) working in alkaline media is of paramount importance to meet the growing demand for hydrogen energy, yet it remains a major challenge because of the slow water dissociation kinetics. Herein, a series of cation metal-doped MoSe2-based catalysts with enriched edge active sites using a straightforward one-pot hydrothermal treatment are designed, which concurrently consider the modulation of the electronic environment and effective exposure of active sites via nanostructure engineering. It was found that the NiFe atoms incorporated into MoSe2 (denoted as NiFe@MoSe2 hereafter) could remarkably alter the electronic configuration of the reactive species, enhance the conductivity, and facilitate the electron and mass transfer to accelerate the alkaline HER. Moreover, the highly nanopetal architecture assembled by plenty of NiFe@MoSe2 nanosheets could effectively inhibit undesirable active site masking and evaluate the overall mechanical robustness of the electrode. Consequently, the as-designed NiFe@MoSe2 electrode only required 146 mV to achieve 10 mA cm−2 with a Tafel slope of 79 mV dec−1 in a basic environment, which is superior to the majority of the reported MoSe2-based nanomaterials. The integration of cation metal incorporation and architecture engineering in this work highlights a general and instructive pathway to design diversified energy nanomaterials. [ABSTRACT FROM AUTHOR]

The design of low-cost and high-performance bifunctional catalysts for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) is of great significance for overall water splitting. Herein, RuNi single atom alloy (SAA) decorated on reduced graphene oxide (RuNi@rGO) was synthesized by a facile strategy for use as a bifunctional HER/OER catalyst. The as-obtained RuNi@rGO catalyst exhibits outstanding electrocatalytic activities with an ultralow overpotential for the HER (15 mV) and the OER (240 mV) at a current density of 10 mA cm−2. Density functional theory (DFT) calculations demonstrate that the introduction of Ru single atoms can evidently change the electron distribution and coordination environment around Ni, and reduce the intermediate's adsorption free energy of RuNi@rGO, thus facilitating the HER/OER catalytic rate. Moreover, when used as the cathode and anode of a two-electrode system, the RuNi@rGO-based water splitting device exhibits a low potential of 1.52 V at a current density of 10 mA cm−2, as well as a high faradaic efficiency almost up to 100%, making RuNi@rGO bifunctional electrocatalysts attractive for energy storage and conversion. [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]

The development of high-efficiency and low-cost photocatalysts for hydrogen production reactions is very important to solve energy problems. In this paper we study the photocatalytic H2 evolution activity of a CeO2/CoS2 heterojunction catalyst under visible light. Characterization studies such as XRD and XPS proved the successful synthesis of a CeO2/CoS2 catalyst. The composite catalyst with a CeO2 and CoS2 mass ratio of 1 : 20 had the best activity, and the hydrogen evolution rate reached 5172.20 μmol g−1 h−1. BET and UV-Vis DRS characterization showed that the introduction of CeO2 not only increased the specific surface area of the composite catalyst, but also improved the response of the photocatalyst to visible light. In addition, PL and electrochemical experiments showed that the electrons and holes of the CeO2/CoS2 catalyst could be quickly separated and transferred, thereby accelerating the kinetics of the hydrogen evolution reaction. This work provided an experimental basis for designing a composite photocatalyst with high stability and hydrogen production activity. [ABSTRACT FROM AUTHOR]

A new heteroleptic Ni(II) dithiolate [Nidppe(dtsq)] (Nidtsq) (dppe = 1,2-bis-(diphenylphosphino)ethane, dtsq2− = 3,4-dioxocyclobut-1-ene-1,2-dithiolate) has been synthesised and characterized spectroscopically and by single crystal X-ray diffraction. The single crystal X-ray diffraction study reveals a square planar geometry around the Ni(II) center wherein dtsq2− and dppe ligands exhibit bidentate chelating coordination modes by their respective sulfur and phosphorus centers. The solid-state framework of Nidtsq is stabilized by C–H⋯O, C⋯H, C⋯O and π⋯π intermolecular interactions and the complex displays an interesting pair of intramolecular C–H⋯Ni anagostic interactions. The nature of these interactions has been addressed with Hirshfeld surface analysis, density functional theory, quantum theory of atoms and molecules (QTAIM) and non-covalent interaction-reduced density gradient (NCI-RDG) analyses. Furthermore, the electrocatalytic properties of Nidtsq have been assessed for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The electrocatalytic properties of Nidtsq have been found to be better than those of the previously reported Ni-mtsq complex.17 In the OER, the complex displayed an overpotential of 0.37 V with η10 of 414 mV and a Tafel slope of 237 mV dec−1 and in the HER it exhibited an overpotential of −0.35 V with η10 of −670 mV and a Tafel slope of 368 mV dec−1. Chronoamperometry and chronopotentiometry experiments for four hours in 0.1 M KOH and 0.5 M H2SO4 indicate the robustness of the complex in alkaline and acidic environments and the post-electrocatalytic stability of Nidtsq has been assessed with the aid of FESEM and X-ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

Herein, mesoporous Zn-doped g-C3N4 wrapped CdIn2S4 microsphere nanostructures were fabricated using a simple hydrothermal route. It is found that the CdIn2S4/Zn–g-C3N4 nanocomposite exhibits the most efficient photocatalytic activity for hydrogen evolution. The photocatalytic activity of the CdIn2S4/Zn–g-C3N4 composite presents the optimum performance for hydrogen evolution of 101.74 μmol h−1, which is ∼10.8 and 7.3 times that of pure g-C3N4 and bare CdIn2S4, respectively. The results of varied characterization such as TEM and XPS demonstrate that a tight heterojunction has been successfully built in CdIn2S4/Zn–g-C3N4 nanocomposites, which is highly favorable to limit the recombination of photogenerated electron–hole pairs. Furthermore, Zn could partially replace the C element in the g-C3N4 framework and enhance the separation of photo-induced electrons and holes. Moreover, the incorporation of Zn-doped g-C3N4 nanosheets with mesoporous features considerably improves the photo-stability of CdIn2S4 microspheres. We hope that these CdIn2S4/Zn–g-C3N4 nanocomposites with the tight heterojunction structure may provide new insight into designing novel photocatalysts with high efficiency and excellent stability. [ABSTRACT FROM AUTHOR]

Transition metal nitrides (TMNs) possess remarkable catalytic activity and excellent electrical conductivity, making them appealing candidates for electrocatalytic materials. In this study, we have utilized a lattice reconstruction strategy to synthesize porous single crystal (PSC) Nb4N5 by nitriding single crystal microcubes of NaNbO3, with the goal of achieving superior electrocatalytic performance and stability. The resultant PSC Nb4N5 combines the advantages of single crystals and porous materials with an ordered structure and a significant specific surface area. The synergistic effect of porosity and structural coherence of the porous single crystals produces numerous unsaturated Nb–N coordination sites on the surface, providing abundant active sites for catalyzing the hydrogen evolution reaction (HER). PSC Nb4N5 exhibits outstanding performance in the HER, with an overpotential of only 71.86 mV at a current density of 10 mA cm−2, and maintains its activity for 100 hours. The single crystal nature of PSC Nb4N5 substantially enhances the catalytic stability of the electrode due to the super stability of the single crystals. Our findings manifest that active materials with an elaborately devised porous structure can enhance the HER properties dramatically during the electrocatalytic process in terms of both activity and stability, providing a new strategy for improving the electrocatalytic properties of the active electrode. [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]

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]

The electrocatalytic CO2 reduction reaction (CO2RR) offers a fascinating approach to converting CO2 into valuable chemical feedstocks. Up to now, the development of highly efficient electrocatalysts has been a significant bottleneck in this field. In this study, employing density functional theory (DFT) calculations, we design a range of stable two-dimensional (2D) metalloporphyrin organic frameworks (TM-PMOFs, TM = Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, and Ag, respectively) built by copper clusters and metalloporphyrin (TM-TCPP), whose CO2RR performance is studied in detail. Among them, the 2D cobaltporphyrin-based organic framework (Co-PMOF) is identified to be the best CO2RR electrocatalyst on account of its low limiting potential (−0.53 V), whose enhanced electrocatalytic performance can be attributed to the presence of numerous active sites on both sides of its 2D framework, as well as the synergistic effect between copper clusters and cobaltporphyrins in facilitating CO2 reduction. These findings provide valuable insights and encourage further experimental research on metallic 2D PMOF materials for CO2 electrochemical reduction. [ABSTRACT FROM AUTHOR]