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Exploring efficient non-noble metal catalysts for the hydrogen evolution reaction (HER) will contribute to the development of clean and green energy technologies. Herein, we adopted a "waste utilization" strategy by using readily available and inexpensive coconut shell waste as a carbon source to synthesize carbon materials anchored with a Cu7Co alloy (Cu7Co/C) as a potential electrocatalyst for the hydrogen evolution reaction (HER). Utilizing a combination of hydrothermal and pyrolysis methods, the synthesized Cu7Co/C catalyst showcases superior HER electrocatalytic performance in alkaline solutions, with an overpotential of 134 mV at 10 mA cm−2 and a Tafel slope of 94 mV dec−1. The alloying of Cu and Co within Cu7Co/C markedly improves charge transfer capabilities, enhancing HER electrocatalysis. This research underscores the exceptional catalytic performance and stability of Cu7Co/C nanocomposites in alkaline media for the HER, attributed to a synergistic effect between the carbon derived from coconut shells and the bimetallic Cu7Co alloy. [ABSTRACT FROM AUTHOR]

Electrocatalytic hydrogen generation in alkaline medium has become widely used in a variety of sectors. However, the possibility for additional performance improvement is hampered by slow kinetics. Because of this restriction, careful control over processes such as water dissociation, hydroxyl desorption and hydrogen recombination is required. Covalent organic frameworks (COFs) based on porphyrin and polyoxometalates (POMs) show encouraging electrocatalytic performance, offering a viable route for effective and sustainable hydrogen generation. Their specific architectures lead to increased electrocatalytic activity, which makes them excellent choices for developing water electrolysis as a clean energy conversion method in the alkaline medium. In this regard, TTris@ZnPor and Lindqvist POM were coordinated to create a new eco-friendly and highly active covalent organic framework (TP@VL-COF). In order to describe TP@VL-COF, extensive structural and morphological investigations were carried out through FTIR, 1H NMR, elemental analysis, SEM, fluorescence, UV-visible, PXRD, CV, N2-adsorption isotherm, TGA and DSC analyses. In an alkaline medium, the electrocatalytic capability of 20%C/Pt, TTris@ZnPor, Lindqvist POM and TP@VL-COF was explored and compared for the hydrogen evolution reaction (HER). The TP@VL-COF showed the best catalytic efficiency for HER in an alkaline electrolyte, requiring just a 75 mV overpotential to drive 10 mA cm−2 and outperforming 20%C/Pt, TTris@ZnPor, Lindqvist POM and other reported catalysts. The Tafel slope value also indicates faster kinetics for TP@VL-COF (114 mV dec−1) than for 20%C/Pt (182 mV dec−1) TTris@ZnPor (116 mV dec−1) and Lindqvist POM (125 mV dec−1). [ABSTRACT FROM AUTHOR]

Electrocatalysts for hydrogen production play a crucial role in advancing the green economy. However, the sluggish kinetics of the hydrogen evolution reaction (HER) limited its application. Therefore, efficient strategies with a tailored d-band center adjustment are highly desirable. In this study, we synthesized N, P-doped carbon matrix-confined Mo-doped FeP nanoparticles using a simple strategy to optimize the catalyst's d-band center. Mo-FeP@NPC presents an excellent HER performance of 63 mV (H2SO4) and 116 mV (KOH) at −10 mA cm−2 in acid and alkaline electrolytes, separately. Theoretical calculations confirm that the outstanding HER performance originates from the strong electronic coupling between atoms, thus upshifting the d-band center and increasing H intermediate adsorption on the active sites. Furthermore, the N, P-doped carbon matrix protects the Mo-doped FeP nanoparticles from aggregation, exposing more active sites during hydrogen production. This work provides new avenues for applying highly efficient metal phosphide catalysts for the HER. [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]

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]

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]

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]

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]

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 electrolysis of water, particularly proton exchange membrane (PEM) water electrolysis, holds great promise for hydrogen production in industry. However, the catalyst used in this process is prone to dissolution in acidic environments, making it imperative to develop cost-effective, highly efficient, and acid-stable electrocatalytic materials to overcome this challenge and enable large-scale application of PEM water electrolysis technology. Herein, we prepared ruthenium oxide (RuO2)/graphitic carbon nitride (g-C3N4) composites (RuO2/C3N4) via a combination of sol–gel and annealing methods. The g-C3N4 provides a large surface area, while RuO2 is uniformly deposited on the g-C3N4 surface. The interaction between g-C3N4 and RuO2 stabilizes the RuO2 nanoparticles and enhances long-term water oxidation stability. This unique structure and the combined advantages of RuO2 and g-C3N4 yield exceptional electrocatalytic activity toward both the oxygen evolution reaction (OER, 240 mV@10 mA cm−2) and the hydrogen evolution reaction (HER, 109 mV@10 mA cm−2), with excellent durability (over 28 h), and a cell voltage of 1.607 V at 10 mA cm−2 when used in an RuO2/C3N4‖‖RuO2/C3N4 electrolyzer. This study highlights the efficacy of the g-C3N4 support method in designing highly stable Ru-based OER electrocatalysts for efficient acidic water splitting. [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]

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]

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]

A two-step simple and efficient ion-exchange chemical strategy is proposed to obtain nanostructured Bi2S3 electrodes of different surface morphologies from the Bi2O3. In the first step, nanoplates of the Bi2O3 are obtained on nickel-foam using successive ionic layer adsorption and reaction method at room-temperature (25 °C). In the second phase, as-obtained nanoplates of the Bi2O3 are transferred to the Bi2S3 using four autoclaves containing different sulfur precursor solutions at 120 °C for 8 h for phase change, structural conversion and surface morphological modification (i.e., walnuts, network-type, nanowires, and nanoflowers). Due to higher surface area and conductivity, lower charge transfer resistance, and reduced band gap caused by ionic and phase conversion, the Bi2S3 surpasses the Bi2O3 in hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities. The overpotential of 112–370 mV for the Bi2S3 network is much lower than that of the nanoplates of the Bi2O3 (275–543 mV), and walnuts (134–464 mV), nanowires (125–500 mV), and nanoflowers (194–520 mV) of the Bi2S3. The Bi2S3 network-type Bi2S3 electrode shows considerable chemical stability through cycling measurement, suggesting the importance of the present study in obtaining metal sulfides from metal oxide with better water splitting activities. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) electrocatalysts are critical in minimizing energy loss during the anodic four-electron transfer process that is required for water oxidation. Improving and selecting optimal non-noble OER electrocatalysts are key strategies for elevating their overall performance and efficiency of energy storage and conversion. Eight NiCo2O4 electrocatalysts were synthesized using the hydrothermal method by changing the amount of urea as a nucleation agent and hydrothermal and calcination temperature to achieve an outstanding catalyst in terms of morphology and electrochemical activity. For examining the physicochemical properties of the electrocatalyst, analyses such as XRD, SEM, TEM, and EDS were conducted. Although XRD analysis revealed the formation of pure NiCo2O4 for all eight samples, SEM and TEM analysis unraveled the best electrocatalyst in terms of morphology to be NiCo-S3 (urea: 10 times higher, Thydrothermal: 120 °C, and TCalcination: 350 °C) and NiCo-S4 (urea: 10 times higher, Thydrothermal: 120 °C, and TCalcination: 400 °C) with a mum-flower-like shape and particle dimension between 20 and 45 nm. NiCo-S4 displayed robust electrochemical activity, primarily in the OER, with an overpotential of 327 mV at 10 mA cm−2 in 1.0 M aqueous KOH solution. The OER performance was enhanced as demonstrated by the exceptional durability of >24 hours and a Tafel slope of 79.7 mV dec−1. Electrochemical impedance spectroscopy (EIS) revealed a low resistance of 1.03 Ω and a double-layer capacitance of 2.43 mF cm−2, substantiating the outstanding OER performance of NiCo-S4. [ABSTRACT FROM AUTHOR]

Transition metal/nitrogen-doped carbon catalysts (M–N–C) show superior catalytic activity in electrocatalytic CO2 reduction due to their high atomic efficiency. In this work, a series of electrocatalysts with cobalt phthalocyanine (CoPc) highly dispersed on M–N–C were prepared. Compared to the pure M–N–C materials, all CoPc/M–N–C catalysts showed a significantly enhanced activity for CO2 reduction and suppressed hydrogen evolution reaction. Among these catalysts, CoPc/Fe–N–C exhibits an outstanding activity and selectivity for CO2 reduction with 99% faradaic efficiency for CO at a potential of −0.48 V vs. RHE. Obviously, such a composite strategy is considered as one of the effective methods to improve the selectivity of CO2 to CO. [ABSTRACT FROM AUTHOR]

Electro-catalytic water splitting is widely viewed as an efficient and viable strategy for green hydrogen production. Herein, we designed nanostructured nickel–cobalt alloy grown on the reduced graphene oxide-single walled carbon nanotube (rGO-SWCNT) thin film by means of electro-deposition, which was used to catalyze water splitting for hydrogen evolution reaction (HER) in an alkaline medium. It was found that the HER performance of nickel–cobalt alloys was determined by the Co/Ni ratio and better than their corresponding single components Co and Ni. Nickel–cobalt alloy with a Co/Ni ratio of 2 (CoNi21) exhibited the most notable HER efficiency with an overpotential of 83.5 mV and 291.8 mV vs. reversible hydrogen electrode at 10 mA cm−2 and 100 mA cm−2, respectively. Furthermore, the significantly lower Tafel slope (112.6 mV dec−1) of CoNi21 indicates that the HER kinetics of the nickel–cobalt alloy is accelerated due to the synergistic effect of Ni and Co. The charge-transfer resistance of CoNi21 is significantly low compared to any single component, validating the intensified interfacial charge transfer. Besides, CoNi21 has the highest active surface area of 147.1 mF cm−2 on the basis of the ECSA measurements, which can be beneficial for providing rich active sites. The CoNi21 catalyst offered excellent durability for HER in the alkaline medium. This work provides a combinatorial method integrating rich interfaces of Co–Ni alloy on highly conductive carbon substrate to design efficient and low-cost electrocatalysts for improving the HER performance. [ABSTRACT FROM AUTHOR]

It is highly urgent to develop efficient and stable non-precious metal electrocatalysts for water splitting. Here, we have successfully prepared a phytic acid (PA)-treated NiFe layered double hydroxide (LDH) catalyst. NiFe-LDH(PA) exhibits excellent catalytic activity towards the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and overall water splitting (OWS) (η10 = 112 mV and η100 = 198 mV for the HER, η100 = 260 mV for the OER, and 1.69 V for OWS @ 100 mA cm−2) as well as remarkable stability during long-term testing (100 h for the HER, 90 h for the OER, and 100 h for OWS). The PA treatment accelerates the catalytic kinetics of NiFe-LDH(PA) and exposes more active sites, leading to enhanced charge transfer. This work demonstrates the significant potential of organic small molecules in modifying the performance of conventional catalysts. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and photocatalytic hydrogen evolution reaction (HER) performance of a series of metal–organic gels (MOGs) constructed from titanium(IV)-oxo clusters and dicarboxylato linkers (benzene-1,4-dicarboxylato and 2-aminobenzene-1,4-dicarboxylato) are described. All the MOGs exhibit a microstructure comprised of metal–organic nanoparticles intertwined into a highly meso-/macroporous structure, as demonstrated by cryogenic transmission electron microscopy and gas adsorption isotherms. Comprehensive chemical characterization enabled the estimation of the complex formula for these defective materials, which exhibit low crystallinity and linker vacancies. To gain deeper insights into the local structure, X-ray absorption fine structure (XAFS) spectroscopy experiments were performed and compared to that of the analogous crystalline metal–organic framework. Additionally, the ultraviolet–visible absorption properties and optical band gaps were determined from diffuse reflectance spectroscopy data. The MOGs were studied as light absorbers for the sacrificial photocatalytic HER under simulated solar light irradiation using a platinum co-catalyst by either (1) in situ photodeposition or (2) ex situ doping process, through a post-synthetic metalation of the MOG structure. The chemical analysis of the metalation, along with high-angle annular dark-field scanning transmission electron microscopy, revealed that although the in situ addition of the co-catalyst led to greater HER rates (227 vs. 110 μmolH2 gMOG−1 h−1 for in situ and ex situ, respectively), the ex situ modification provided a finer distribution of platinum nanoparticles along the porous microstructure and, as a result, it led to a more efficient utilization of the co-catalyst (45 vs. 110 mmolH2 gPt−1 h−1). [ABSTRACT FROM AUTHOR]

To develop hydrogen energy production and address the issues of global warming, inexpensive, effective, and long-lasting transition metal-based electrocatalysts for the synthesis of hydrogen are crucial. Herein, a porous electrocatalyst NiMo/Ni/NF was successfully constructed by a two-step electrodeposition process, and was used in the hydrogen evolution reaction (HER) of electrocatalytic water decomposition. NiMo nanoparticles were coated on porous Ni/NF grown on nickel foam (NF), leading to a resilient porous structure with enhanced conductivity for efficient charge transfer, as well as distinctive threedimensional channels for quick electrolyte diffusion and gas release. Notably, the low overpotential (42 mV) and fast kinetics (Tafel slope of 44 mV dec-1) at a current density of 10 mA cm-2 in 1.0 M KOH solution demonstrate the excellent HER activity of the electrode, which was superior to that of recently reported non-noble metal-based catalysts. Additionally, NiMo/Ni/NF showed extraordinary catalytic durability in stability tests at a current density of 10 mA cm-2 for 70 h. The porous structure catalyst and the electrodeposition-electrocatalysis technique examined in this study offer new approaches for the advancement of the electrocatalysis field because of these benefits. [ABSTRACT FROM AUTHOR]

As a dual-functional catalyst for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), Ru clusters have great potential, but there are certain difficulties regarding their stability on the substrate and the tunability of their electronic environment. Here, the S doped graphited biochar aerogel electrocatalyst was designed and synthesized using terrestrial lignin and algal polysaccharide as a carbon substrate. The Ru clusters were anchored on the S-doped carbon aerogel (P-Ru/SC) by carefully designing the Ru-S bond via a novel plasma assisted high temperature carbonization treatment. The optimized P-Ru/SC-2 catalyst exhibits excellent electrocatalytic performance for the HER and OER, achieving ultra-small overpotentials of 119.6 mV and 193.4 mV at 10 mA cm-2. The dual-electrode requires only 1.47 V to reach 10 mA cm-2. It is worth noting that a large number of S sites on graphited carbon can strongly interact with the Ru clusters, significantly improving the catalytic activity and stability for the HER and OER. [ABSTRACT FROM AUTHOR]

The design and construction of a duo-active electrocatalyst with effective performance and enhanced stability for overall water splitting have been in the spotlight to meet the demand for renewable energy. Herein, we report the fabrication of a stannatranone pillared metal-organic framework via a coprecipitation approach and further its decoration with gold nanoparticles (size D 10.86 nm) for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The Au-anchored Sn-Na MOF (Au NPs/Sn-Na MOF) exhibited a remarkable electric activity with low overpotential (Z) of 129 mV for the HER at a current density of 10 mA cm-2, and 650 mV for the OER at a current density of 20 mA cm-2. The slope values were found to be 62.3 mV dec-1 and 37.8 mV dec-1, respectively. The heightened OER and HER activities can be ascribed to its substantial electrochemically active surface area of 17.4 mF cm-2. The mechanistic studies revealed that Au NPs/Sn-Na MOF provides active surface sites for water adsorption and facilitates subsequent dissociation to form H2 and O2. Furthermore, the pillared structure of the MOF with stannatranone knots made the skeleton highly stable under basic conditions for its potential application in overall water splitting. [ABSTRACT FROM AUTHOR]

Interfacial engineering emerges as a potent strategy for regulating the catalytic reactivity of metal phosphides. Developing a facile and cost-effective method to construct bifunctional metal phosphides for highly efficient electrochemical overall water splitting remains an essential and challenging issue. Here, a multiphase transition metal phosphide is constructed through the direct phosphorization of a Ni–Co metal–organic framework grown on nickel foam (Ni–Co-MOF/NF), which is prepared by utilizing nickel foam as conductive substrate and nickel source. The resulting transition metal phosphide manifests a pillar-layered morphology, wherein CoP, Ni2P, and Ni5P4 nanoparticles are embedded within each carbon sheet and these carbon sheets assemble into a pillar-shaped structure on the nickel foam (Ni2P–Ni5P4–CoP–C/NF). The heterogeneous Ni2P-Ni5P4–CoP–C/NF with multiple interfaces serves as a highly efficient bifunctional electrocatalyst with overpotentials of −100 mV and 293 mV in the hydrogen evolution reaction and oxygen evolution reaction, respectively, at 50 mA cm−2 in alkaline media. This superior catalytic performance should mainly be ascribed to its enriched active centers and multiphase synergy. When directly applied for alkaline overall water splitting, the Ni2P–Ni5P4–CoP–C/NF couple demonstrates satisfactory activity (1.55 V @10 mA cm−2) along with sustained durability over 18 hours. This method brings fresh enlightenment to the economical and controllable preparation of multi-metal phosphides for energy conversion. [ABSTRACT FROM AUTHOR]

Heteroatomic anion doping represents a powerful approach for manipulating the electronic configuration of the active metal locus in electrocatalysts, resulting in enhanced multifunctional electrocatalytic properties in hydrogen/oxygen evolution reactions (HER/OER). Here, fluorine-tailored Ni2P-F3 nanosheets were synthesized and evaluated as a robust multifunctional electrocatalyst for HER, OER, and UOR. Our comprehensive experimental and theoretical investigations reveal that the anionic F effectively tailored the electronic states of the Ni2P-F3 nanosheets, resulting in an elevated d-band center and optimizing the sorption capacity of intermediates. In addition to thermodynamically and kinetically favoured redox reactions, F doping facilitates the reconstruction and generation of active γ-NiOOH. Resulting from the optimized electronic configuration and nanosheet architecture, outstanding catalytic activities are demonstrated by Ni2P-F3 with low overpotentials to reach 100 mA cm−2 for HER (177 mV) and OER (293 mV), surpassing Ni2P by 234 and 205 mV, respectively. Notably, 1.618 V is required for full-water-diversion to reach 10 mA cm−2, while 1.414 V is required with urea oxidation for 100 mA cm−2. [ABSTRACT FROM AUTHOR]

Leveraging solar energy through photocatalytic hydrogen production from water stands out as one of the most promising approaches to address the energy and environmental challenges. The choice of catalyst profoundly influences the outcomes of photocatalytic reactions, and constructing heterojunctions has emerged as a widely applied strategy to overcome the limitations associated with single-phase photocatalysts. MoO3, renowned for its high chemical stability, encounters issues such as low photocatalytic efficiency and fast recombination of photogenerated electrons and holes. To tackle these challenges, the morphology of MoO3 has been controlled to form nanorods, simultaneously suppressing the aggregation of the catalyst and increasing the number of surface-active sites. Moreover, to facilitate the separation of photogenerated charge carriers, Cd0.9Zn0.1S nanoparticles with a twin crystal structure are deposited on the surface of MoO3, establishing an S-scheme heterojunction. Experimental findings demonstrate that the synergistic effects arising from the well-defined morphology and interface interactions extend the absorption range to visible light response, improve charge transfer activity, and prolong the lifetime of charge carriers. Consequently, Cd0.9Zn0.1S/MoO3 S-scheme heterojunctions exhibit outstanding photocatalytic hydrogen production performance (3909.79 μmol g−1 h−1) under visible light irradiation, surpassing that of MoO3 by nearly nine fold. [ABSTRACT FROM AUTHOR]

New heteroleptic dppe appended Co(III)-dithiocarbamate (dtc) complex cations with compositions [Co(S2CNEt2)2(dppe)](PF6) (Co-Et), [Co(S2CNPri2)2(dppe)](PF6) (Co-Pr) and [Co(S2CNBun2)2(dppe)](PF6) (Co-Bu) have been synthesized and characterized by microanalysis, spectroscopic methods and crystallographic analysis. The single crystal X-ray diffraction results indicated that in all three complexes, the coordination environment around Co(III) is distorted octahedral and Co(III) is coordinated to four sulfur centers of the two dtc ligands and the two phosphorus centers of the dppe ligand. These complexes serve as precursors to yield cobalt sulfide/cobalt phosphide nano-composites dCo-Et, dCo-Pr and dCo-Bu by solvothermal decomposition of Co-Et, Co-Pr and Co-Bu, respectively. The decomposed materials have been characterized by PXRD and SEM-EDAX and explored as potential electrocatalysts for both oxygen evolution and hydrogen evolution reactions in basic and acidic media, respectively. Catalytic activity is dependent on the precursor complex and best OER and HER activities are observed for dCo-Bu with an η10 of 230 mV and a Tafel slope of 192.11 mV dec−1 for the OER and an η10 of 470 mV and a Tafel slope of 126.21 mV dec−1 for the HER. [ABSTRACT FROM AUTHOR]

Seawater, a plentiful natural resource, is promising for hydrogen production compared to traditional electrocatalytic methods based on high-purity freshwater. This strategy shift addresses the challenge of limited freshwater resources and holds significant potential for desalination applications. Hence, identifying effective electrocatalysts for seawater electrolysis is imperative to alleviate freshwater resource scarcity and achieve large-scale hydrogen production. Herein, we report a catalyst comprising zero-dimensional (0D) nitrogen-doped carbon-coated FeNi3 nano-particles (FeNi3-NC) grown on NiFeOx nano-sheets for the hydrogen evolution reaction in alkaline seawater. The combination of FeNi3-NC and NiFeOx significantly enhances interfacial interactions, resulting in an elevated rate of electron transfer. The FeNi3-NC/NiFeOx catalyst requires a low overpotential of 65 mV to achieve a current density of 10 mA cm−2 in alkaline seawater. In addition, the electrolytic cell constructed using it and its precursor also exhibits excellent water-splitting characteristics and it exhibits remarkable long-term stability and corrosion resistance. This discovery presents an innovative approach for designing zero-dimensional/two-dimensional catalysts to facilitate large-scale hydrogen production through seawater electrolysis. [ABSTRACT FROM AUTHOR]

Tin disulfide (SnS2) is a highly promising anode material for sodium-ion batteries (SIBs) due to its substantial theoretical capacity stemming from alloying reactions and conversion mechanisms. Eliminating non-conductive binders and simplifying fabrication, the binder-free SnS2@carbon cloth (SnS2@CC) electrode is gaining attention. In this study, a one-step solvothermal synthesis was applied to fabricate binder-free SnS2@CC structures as SIB anodes. The electrochemical performance was enhanced by doping copper (Cu) into the SnS2 lattice. Solvothermal duration and Cu doping levels were systematically investigated to optimize the electrochemical properties of anodes. The Cu-doped SnS2@CC (Cu–SnS2@CC) electrodes exhibited superior electrical conductivity and sodium ion diffusion coefficients compared to those for the SnS2@CC electrodes. After 30 cycles, the Cu–SnS2@CC electrode prepared using a 15-h solvothermal process and 2% Cu doping achieved the highest capacity of 1092.8 mA h g−1 at 0.1 A g−1, while the SnS2@CC electrode yielded only 436.4 mA h g−1 under the same conditions. The optimized Cu–SnS2@CC electrode demonstrates excellent rate performance and cycling stability, with a capacity retention of 63% and Coulombic efficiency of 100% after 130 charge/discharge cycles. This research paves the way for high-performance, binder-free SnS2-based anodes in SIBs. [ABSTRACT FROM AUTHOR]

To date, researchers in chase of economic cost-efficiency are faced with the problem of developing effective catalysts for water splitting without the use of platinoids. Herein, catalytic properties of hexanuclear rhenium cluster complexes are investigated in application to the hydrogen evolution reaction (HER). A paste composite electrode containing the cluster complexes was obtained, producing a current density of 10 mA cm−2 at an extraordinarily low overpotential of 90 mV (RHE). The {Re6Se8}-based complexes have shown very favorable reaction kinetics via 102 mV dec−1 value of the Tafel slope for HER reaction within the composition of the paste electrode. Model calculations of kinetic parameters using density functional theory also support the experimental findings. This work underscores the perspectivity of rhenium cluster compounds in HER and opens a promising avenue toward the practical implementation of hydrogen production through electrochemical water splitting. [ABSTRACT FROM AUTHOR]

In contrast to the energy-consuming Haber–Bosch process, ammonia synthesis by electrocatalysis under ambient conditions is an efficient and environmentally friendly method. In this work, through first principles calculations, the potential of four dual-atom FeTM (TM = Fe, Mo, Co, and V) anchored graphyne (FeTM@GY) as efficient nitrogen reduction reaction (NRR) catalysts is systematically investigated. Among them, FeMo@GY is the most promising, with excellent NRR catalytic activity, high ability to suppress the competing hydrogen evolution reaction (HER), and good stability. Moreover, NRR prefers the maximum pathway with the calculated onset potentials of −0.27 V for FeMo@GY. This work not only suggests that FeMo@GY holds great promise as an efficient, low-cost, and stable dual-atom catalyst for NRR but also further provides a guiding idea for the design of efficient NRR catalysts. [ABSTRACT FROM AUTHOR]

This study developed an efficient photocatalyst for hydrogen production, consisting of CdS nanorods and the CoTPPBr4 co-catalyst. The synthesized photocatalyst was characterized using a suite of techniques including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), photoluminescence (PL) spectroscopy, and ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS). Additionally, transient photocurrent response and electrochemical impedance spectroscopy (EIS) were carried out to further probe the material's properties. Our findings demonstrate that the CoTPPBr4 co-catalyst significantly enhances the photocatalytic H2 evolution efficiency under visible light irradiation. Notably, among the tested photocatalysts, a 12.5% CoTPPBr4/CdS composite exhibited the most superior photocatalytic performance, achieving a hydrogen production rate of 41.3 mmol g−1 h−1, which is 4.1 times higher than that of pristine CdS. The introduction of CoTPPBr4 effectively facilitates charge transfer within CdS, enhances the separation efficiency of light-induced electron–hole pairs, and boosts the surface H2-evolution kinetics. This research not only introduces a promising photocatalyst for visible light-driven hydrogen production but also provides a way for the development of highly efficient and stable CdS-based hybrid semiconductor nanocomposites suitable for diverse photocatalytic applications. [ABSTRACT FROM AUTHOR]

The development of high-performance and highly stable electrocatalysts is crucial and challenging for the hydrogen evolution reaction (HER). MOFs complexed with SnS2 can form complexes with inserted structures, and their large specific surface area and numerous pores favor mass transfer, exposing the S active sites to more SnS2, improving the utilisation of the active sites and enhancing the catalytic activity for the HER. Structural collapse can be hindered to improve the stability of the HER composites. Herein, six different kinds of SnS2 were synthesized by a hydrothermal method under discrete conditions, and SI8-SnS2 was screened out to have optimal morphology and electrocatalytic performance. Two innovative SnS2@Ni-MOF and SnS2@HKUST-1 as efficient electrocatalysts were synthesized by a facile grinding method for hydrogen generation. SnS2@Ni-MOF and SnS2@HKUST-1 catalysts showed lower overpotentials of 117 mV and 142 mV at 10 mA cm−2 (η10) and smaller Tafel slopes (58 mV dec−1 and 93 mV dec−1) than six different kinds of SnS2, Ni-MOF and HKUST-1 in 0.5 M H2SO4. Meanwhile, the Cdl values for SnS2@Ni-MOF and SnS2@HKUST-1 were estimated to be 11.5 mF cm−2 and 8.0 mF cm−2, and the stabilities of SnS2, Ni-MOF, HKUST-1, SnS2@Ni-MOF, and SnS2@HKUST-1 were tested at a current density of 10 mA cm−2. The current densities of SnS2@Ni-MOF and SnS2@HKUST-1 were stable over 8 h compared to the pure samples, and SEM, XPS tests were run after the HER test, indicating that the materials have excellent electrocatalytic stability. The syntheses of SnS2@Ni-MOF and SnS2@HKUST-1 enhance their intrinsic catalytic activity, and the porous structure promotes mass transfer efficiency, thereby improving the HER performance, which will guide the development of new and promising electrocatalysts for HER. [ABSTRACT FROM AUTHOR]

Mn-doped Bi3O4Br has been synthesized using a solvothermal route. The undoped Bi3O4Br and Mn–Bi3O4Br materials possess orthorhombic unit cells with two distinct Bi sites forming a layered atomic arrangement. The shift in the (020) plane in the powder X-ray diffraction (PXRD) pattern confirms Mn-doping in the Bi3O4Br lattice. Elemental mapping indicated 7% Mn doping in the Bi3O4Br lattice structure. A core-level X-ray photoelectron study (XPS) indicates the presence of BiIII and MnII valence-states in Mn–Bi3O4Br. Doping with a cation (MnII) containing a different charge and ionic radius resulted in vacancy/defects in Mn–Bi3O4Br which further altered its electronic structure by reducing the indirect band gap, beneficial for electron conduction and electrocatalysis. The irreversible MnII to MnIII transformation at a potential of 1.48 V (vs. RHE) precedes the electrochemical oxygen evolution reaction (OER). The Mn-doped electrocatalyst achieved 10 mA cm−2 current density at 337 mV overpotential, while the pristine Bi3O4Br required 385 mV overpotential to reach the same activity. The pronounced OER activity of the Mn–Bi3O4Br sample over the pristine Bi3O4Br highlights the necessity of MnII doping. The superior activity of the Mn–Bi3O4Br catalyst over that of Bi3O4Br is due to a low Tafel slope, better double-layer capacitance (Cdl), and small charge-transfer resistance (Rct). The chronoamperometry (CA) study depicts long-term stability for 12 h at 20 mA cm−2. An electrolyzer fabricated as Pt(−)/(+)Mn–Bi3O4Br can deliver 10 mA cm−2 at a cell potential of 2.05 V. The post-CA-OER analyses of the anode confirmed the leaching of [Br−] followed by in situ formation of Mn-doped Bi2O3 as the electrocatalytically active species. Herein, an ultra-low Mn-doping into Bi3O4Br leads to an improvement in the electrocatalytic performance of the inactive Bi3O4Br material. [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]

The electrolysis of seawater has become a preferred method for hydrogen production since the current shortage of freshwater resources, offering an effective strategy to address the energy crisis. Nevertheless, this technology is limited by the following two factors: (i) low stability of catalytic materials at high-current density and (ii) accelerated corrosion rate of the electrode due to high concentrations of chloride ions (Cl−). Herein, an ultrafine phosphorus (P) and ruthenium (Ru) co-doped cerium dioxide (CeO2) self-supporting electrode (P, Ru–CeO2) was constructed via a high-pressure treatment strategy. Under the oxygen vacancies (Ov) in the CeO2 support and the anionic protective layer formed by the P–O bond, the electrode exhibits exceptional catalytic activity and durability in saline-alkali water, which only requires 291 mV to reach 1000 mA cm−2 in 1 M KOH + 1.5 M NaCl electrolyte. Besides, the electrode could operate stably at 1000 mA cm−2 over 100 h without significant attenuation, which can reach the level of industrial water electrolysis. This work presents a novel approach to designing and engineering excellent catalysts for industrial water electrolysis. [ABSTRACT FROM AUTHOR]

In this study, a trimetallic catalyst, NiWRu@NF, is electrodeposited onto nickel foam using chronoamperometry to enhance the hydrogen evolution reaction (HER) in alkaline water electrolysis. The catalyst combines nickel, tungsten, and ruthenium components, strategically designed for efficiency and cost-effectiveness, hydroxyl transfer and water dissociation, and acceleration of hydrogen combination, respectively. Evaluation of NiWRu@NF reveals exceptional performance, with a low overpotential of -50 mV and high current density of -10 mA cm-2, signifying its efficiency in promoting HER. Tafel values further corroborate the catalyst's effectiveness, indicating a rapid reaction rate of hydrogen evolution in such a highly alkaline medium compared to other controls studied along with it. This study underscores the significance of NiWRu@NF in advancing alkaline HER kinetics, paving the way for more efficient electrolysis processes. [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]

A 3D hierarchical nickel--iron hexacyanoferrate electrocatalyst was successfully grown on nickel foam using an energy-efficient in situ self-assembly method. The as-prepared NiFeHCF@NF electrode has good morphology and intimate contact with the NF compared to electrodes from the co-precipitation method. The well-designed NiFeHCF@NF nanostructure delivers prominent performances that require overpotentials as low as 210 and 125 mV@10 mA cm-2 for the OER and HER in 1 M KOH, respectively. Tafel slope and electrochemical impedance studies further revealed favourable kinetics during electrolysis. Hence, an NiFeHCF@NF--NiFeHCF@NF water electrolyser only required 1.56 V@10 mA cm-2 with an ~2.5% potential loss. Furthermore, the synergistic effect of iron and nickel with ferrocyanide improved the structural stability and promoted the generation of active phases during the OER/HER, resulting in outstanding durability for 150 h. Moreover, the novel all-in-one strategy can be used to explore other bifunctional and cost-efficient electrocatalysts for various applications. The solar-based water electrolysis and environmental assessment confirmed the practical use of NiFeHCF@NF for eco-friendly industrial hydrogen production. [ABSTRACT FROM AUTHOR]

Designing cost-effective catalysts with the structural features and necessary functionality to drive ammonia borane hydrolysis for hydrogen generation remains a challenge. In this work, a close heterojunction of Fe3O4--Ni2P uniformly embedded in amorphous carbon material (Fe3O4--Ni2P@C) has been prepared via surface phosphorization. The catalyst displays superior activity with a turnover frequency (TOF) of 92.8 min-1 and favorable durability for ammonia borane hydrolysis, making it superior to most reported nickel-based catalysts. The theoretical studies show a high electron density on the Fe3O4--Ni2P heterojunction. Combining the theoretical and experimental results, the dual active sites at the heterojunction are beneficial to the adsorption of reactant molecules and the reduction of the reaction barrier. This strategy of constructing an appropriate heterojunction to maximize synergistic effects may open a new avenue for non-precious metal catalysis. [ABSTRACT FROM AUTHOR]

Efficient and stable oxygen evolution reaction (OER) electrocatalysts are essential for improving the overall efficiency of water electrolyzers. Iron-doped cobalt phosphide (CoFeP) nanowires are prepared via a one-step solvothermal process using a cobalt metal--organic framework (Co MOF), P4 and dissolved Fe2+. The ion-exchange between Fe2+ and the Co MOF occurs first, and then phosphides are formed. CoFeP exhibits the Co2P phase, and there exists an electronic interaction between Co and Fe. When supported on nickel foam (NF) to catalyze the OER in alkaline solutions, CoFeP/NF exhibits an overpotential of 240 mV at a 10 mA cm-2 OER current density, which is much lower than that of Co2P/NF. Kinetic analyses indicate that the lattice oxygen oxidation mechanism occurs at the CoFeP/NF surface, whereas the adsorbate evolution mechanism dominates at the Co2P/NF surface. The change in the mechanistic pathway is due to the increased acidity of the Co4+ site in CoFeP, which favors the decoupled proton--electron transfer process. Lower apparent activation energy, charge transfer resistance and Tafel slope values, and higher electron rate constants are observed on the CoFeP/NF surface, and the charge redistribution induced by Fe during the OER process alters the adsorption energy of the hydroxyl groups at the Co sites, leading to more facile OER kinetics, as proved by density functional theory calculations. CoFeP/ NF shows good long-term durability in alkaline solutions, and the conversion of surface phosphides to oxides and (oxy)hydroxides is observed. [ABSTRACT FROM AUTHOR]

A new polyoxometalate (POM)-based hybrid nanomaterial (denoted as PMo11-Cr-mGO) was designed via covalent interaction between the Cr(acac)3 complex and [PMo11O39]7− followed by immobilization on the surface of modified graphene oxide (mGO). The prepared nanomaterial was characterized using a series of physicochemical techniques. X-ray diffraction (XRD), Raman analysis, transmission electron microscopy (TEM), and FE-SEM-EDS revealed the preservation of layered GO during the formation of the desired hybrid nanomaterial. Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and elemental analysis confirmed the immobilization of POM (PMo11-Cr) on the surface of mGO and the formation of PMo11-Cr-mGO. In order to evaluate the performance of PMo11-Cr-mGO in the hydrogen evolution reaction (HER), electrochemical measurements were also performed. The resulting PMo11-Cr-mGO exhibited excellent HER activities with a low overpotential of 153 mV at 10 mA cm−2 and good durability in acidic media, thus emerging as one of the most efficient POM-based electrocatalysts. [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]

The designing of efficient electrocatalysts for hydrogen generation is essential for the practical application of water-splitting devices. With numerous electrochemical advantages, transition metal sulphides are regarded as the most promising candidates for catalysing the hydrogen evolution reaction (HER) in acidic media. In the present study, Ru-doped cobalt sulphide nanosheets, termed Co9S8/Ru@t (t = 24 h, 48 h, and 72 h), were obtained by varying the reaction time from 24 h to 72 h from a RuCo-PBA precursor. The role of the time period for the synthesis of Co9S8/Ru@48h is vital in increasing the number of electroactive sites and optimising the hydrogen adsorption–desorption phenomena leading to an increment in the HER activity. The electrochemical outcomes demonstrate that the optimized Co9S8/Ru@48h requires a low overpotential of just 94 mV to produce 10 mA cm−2 current density, and also exhibits a lower Tafel slope value of 84 mV dec−1 defining its faster reaction kinetics. The as-synthesized Co9S8/Ru@48h was stable for up to 20 h of constant electrolysis signifying its outstanding durability. The optimized synthetic approach and impressive electrochemical results make Co9S8/Ru@48h a suitable alternative to noble-metal-based electrocatalysts for the HER. [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]