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Development of high-performance, low-cost catalysts for electrochemical water splitting is key to sustainable hydrogen production. Herein, ultrafast synthesis of carbon-supported ruthenium-copper (RuCu/C) nanocomposites is reported by magnetic induction heating, where the rapid Joule's heating of RuCl3 and CuCl2 at 200 A for 10 s produces Ru-Cl residues-decorated Ru nanocrystals dispersed on a CuClx scaffold, featuring effective Ru to Cu charge transfer. Among the series, the RuCu/C-3 sample exhibits the best activity in 1 m KOH toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with an overpotential of only -23 and +270 mV to reach 10 mA cm-2, respectively. When RuCu/C-3 is used as bifunctional catalysts for electrochemical water splitting, a low cell voltage of 1.53 V is needed to produce 10 mA cm-2, markedly better than that with a mixture of commercial Pt/C+RuO2 (1.59 V). In situ X-ray absorption spectroscopy measurements show that the bifunctional activity is due to reduction of the Ru-Cl residues at low electrode potentials that enriches metallic Ru and oxidation at high electrode potentials that facilitates the formation of amorphous RuOx. These findings highlight the unique potential of MIH in the ultrafast synthesis of high-performance catalysts for electrochemical water splitting.

A metal-insulator-semiconductor (MIS) structure holds great potential to promote photoelectrochemical (PEC) reactions, such as water splitting and CO2 reduction, for the storage of solar energy in chemical bonds. The semiconductor absorbs photons, creating electron-hole pairs; the insulator facilitates charge separation; and the metal collects the desired charge and facilitates its use in the electrochemical reaction. Despite these attractive features, MIS photoelectrodes are significantly limited by their photovoltage, a combination of the voltage generated from photon absorption minus the potential drop across the insulator. Herein, we use multiscale continuum modeling of the carrier, electrolyte, and interfacial transport to identify strategies for mitigating the deleterious potential drop across the insulator and enabling high MIS photovoltages. To this end, we model Ni/SiO2/n-Si photoanodes that employ a planar Ni film or Ni nanoparticles (np-MIS) and validate both models using experimental polarization curves and photovoltage measurements from the literature. The simulations reveal that the insulator potential drop is lower and hence achieves higher photovoltages for np-MIS structures than MIS structures because the electrolyte screens charge trapped at defect states between the semiconductor and the insulator. This electrolyte charge screening phenomenon can be further leveraged by using low loadings or small nanoparticles, which not only minimize the interfacial potential drop but also improve the photocurrent by enabling more light absorption. These insights contribute to the optimization of the np-MIS structures for sustainable energy conversion.

[Display omitted] Developing high active and stable cost-effective bifunctional electrocatalysts for overall water splitting to produce hydrogen is of vital significance in clean and sustainable energy development. This work has prepared a novel porous unreported MOF (Ni-DPT) as a precursor to successfully synthesize a non-noble bifunctional NiCoP/Ni 12 P 5 @NF electrocatalyst through doping strategy and interface engineering. This catalyst is constructed by layered self-supporting arrays with heterojunction interface and rich nitrogen-phosphorus doping. Structural characterizations and the density function theory (DFT) calculations confirm that the interface effect of NiCoP/Ni 12 P 5 heterojunction can regulate the electronic structure of the catalyst to optimize the Gibbs free energy of hydrogen (ΔG H*); simultaneously, the defect-rich layered nanoarrays can expose more active sites, shorten mass transfer distance, and generate a self-supporting structure for in-situ reinforcing the structural stability. As a result, this NiCoP/Ni 12 P 5 @NF catalyst exhibits favorable electrocatalytic performance, which simply needs overpotentials of 100 mV for HER and 310 mV for OER, respectively, at a current density of 10 mA·cm−2. The anion exchange membrane electrolyzer assembled with this NiCoP/Ni 12 P 5 @NF as both anode and cathode catalysts can operate stably for 200 h at a current density of 100 mA·cm−2 with an insignificant voltage decrease. This work may provide some inspiration for the further rational design of inexpensive non-noble multifunctional electrocatalysts and electrode materials for water splitting to generate hydrogen. [ABSTRACT FROM AUTHOR]

[Display omitted] The design of low-cost, efficient, and stable multifunctional basic catalysts to replace the high-cost noble metal catalysts remains a challenge. In this work, we report a dual-component Co-W 2 C catalytic system which achieves excellent properties of hydrogen evolution reaction (HER, η 10 = 63 mV), oxygen evolution reaction (OER, η 10 = 259 mV) and overall water splitting (η 10 = 1.53 V) by adjusting the interfacial electronic structure of the material. Further density functional theory (DFT) calculations indicate that the efficient electronic modulation at the W 2 C/Co interface leads to the generation of favorable hydroxyl and hydrogen species energetics on the hybrid surface. The results of the in-situ Raman spectra show that W 2 C can suppress the excessive oxidation of the active site during the OER process, and the existence of core–shell structure also protects the W 2 C substrate. The stable and efficient catalytic performance of Co-W 2 C is attributed to the common advantages of structural and interface manipulation. [ABSTRACT FROM AUTHOR]

The electronic structures of Fe and Ni in FNS were fine-tuned by P doping, resulting in suppressed Fe leaching, improved electrical conductivity of FNS, and facilitated formation of NiOOH on catalyst surface. In turn, these features enhanced the OER activity and stability. [Display omitted] The pentlandite Fe 5 Ni 4 S 8 (abbreviated as FNS) is not efficient for water splitting because of its inferior performance for the oxygen evolution reaction (OER). This issue originates from the low activity and instability of FNS during the OER process but can be solved through appropriate doping. Herein, a P-doping strategy based on annealing in the presence of NaH 2 PO 2 as a phosphorus source upstream was employed on FNS to enhance its activity and stability toward OER. The results demonstrated fine-tuned electronic structures of Fe and Ni in FNS through P-doping, resulting in suppressed Fe leaching, improved electrical conductivity of FNS, and easier formation of NiOOH on the surface of the catalyst. In turn, these features enhanced the OER activity and stability. The optimal P-doped FNS catalyst FNSP-40 exhibited a 4-fold greater electrochemical surface area compared to that of FNS, accompanied by an overpotential of 235 mV at 10 mA cm−2. The optimized FNSP-40 catalyst was used as an anode, and platinum-decorated FNS was used as a cathode. This combination demonstrated an electrolysis performance with a cell voltage of 1.57 V, reaching a current density of 100 mA cm−2, which indicates efficient operation. The advantages of P-doping engineering were also verified in simulated seawater with enhanced OER performance. Overall, the proposed strategy looks promising for the fabrication of pentlandite-structured catalysts for efficient alkaline water and seawater oxidation. [ABSTRACT FROM AUTHOR]

CoFe-LDH/IF was prepared through the self-corrosion engineering of iron foam, and the CoP 2 -FeP 4 heterojunction was synthesized through phosphating and carburizing processes, forming an interfacial charge distribution and achieving efficient and stable water oxidation for 1000 h. [Display omitted] Electrochemical water splitting stands out as a promising avenue for green hydrogen production, yet its efficiency is fundamentally governed by the oxygen evolution reaction (OER). In this work, we investigated the growth mechanism of CoFe hydroxide formed by in situ self-corrosion of iron foam for the first time and the significant influence of dissolved oxygen in the immersion solution on this process. Based on this, the CoP 2 -FeP 4 /IF heterostructure catalytic electrode demonstrates exceptional OER activity in a 1 M KOH electrolyte, with an overpotential of only 253 ± 4 mV (@10 mA cm−2), along with durability exceeding 1000 h. Density functional theory calculations indicate that constructing heterojunction interfaces promotes the redistribution of interface electrons, optimizing the free energy of adsorbed intermediate during the water oxidation process. This research highlights the importance of integrating self-corroding in-situ growth with interface engineering techniques to develop efficient water splitting materials. [ABSTRACT FROM AUTHOR]

Electrochemical water splitting is vital for green hydrogen production and clean energy. This study introduces a novel approach: platinum nanoclusters (Pt NCs) decorated GaN nanowires (GNWs) on p++-Si substrates to enhance hydrogen generation efficiency. Highly-crystalline GNWs synthesized via commercial metal-organic chemical vapor deposition provide a scalable platform for hydrogen evolution. To address the cost limitations of Pt-based electrocatalysts, we developed a method for loading ultralow Pt NCs via photoelectrochemical deposition. Investigations underscore the Pt–Ga sites' crucial role in promoting efficient H 2 production. The Pt NCs/GNWs/p++-Si electrode achieved −10 mA/cm2 current density at +50 mV vs. the RHE and sustained −20 mA/cm2 for 90 h under harsh acidic conditions at room temperature and atmospheric pressure with nearly 100% retention. This study offers insights into efficient and stable electrodes for electrochemical H 2 generation. • Commercial-scale viable Pt nanoclusters/GNWs/p++-Si electrode is fabricated. • Current density of −10 mA/cm2 with a minimal overpotential of +50 mV is achieved. • 100% retention was found after 90 h, sustaining −20 mA/cm2 at −36 mV. • The impact of Pt NCs & non-polar faceted GNWs on hydrogen generation is explained. [ABSTRACT FROM AUTHOR]

Noble metal-free catalysts have recently attracted much attention towards overall electrochemical water splitting. However, poor kinetics of the reactions, involved in water splitting leads to lower hydrogen production in alkaline electrolytes. Hence, it is essential to design highly active, conductive and cost-efficient catalysts for water electrolysis. Therefore, a bifunctional electrocatalyst based on cobalt oxide (CoO) incorporated over nickel selenide (NiSe 2) supported on nickel foam (CoO/NiSe 2 /NF) was synthesized via a two-step process involving hydrothermal and electrochemical deposition methods. The synthesized material was characterized thoroughly using XRD, XPS, SEM and FE-SEM. After thorough characterization, all the synthesized materials were employed as electrocatalysts towards overall water splitting. The electrochemical studies revealed that CoO/NiSe 2 /NF has demonstrated excellent electrocatalytic activity towards overall electrochemical water splitting. The improved electrochemical activity of nano-hybrid could be attributed to heterogeneous structure, enhanced edge sites and the synergetic cooperation of CoO and NiSe 2. Finally, two electrode setups were prepared to perform overall water electrolysis in which CoO/NiSe 2 /NF need a cell potential of 2.03 V to attain 100 mA cm−2. The study proposes an approach for heterogeneous structure engineering to boost the catalytic performance of noble metal-free materials. [Display omitted] • CoO/NiSe 2 /NF nanohybrid synthesized hydrothermally and electrochemical deposition method. • All synthesized materials were utilized as bifunctional catalysts for overall water splitting. • Interface engineering of CoO and NiSe 2 significantly boosts electrocatalytic activity. • Abundant active sites were obtained by Interface engineering. • CoO/NiSe 2 /NF demonstrated higher activity and stability towards overall water splitting. [ABSTRACT FROM AUTHOR]

Nickel selenide (NiSe) and carbon nanotubes (CNTs) heterojunction structure water electrolysis catalyst was prepared by vapor deposition method, constructing a heterogeneous phase interface between NiSe and CNTs. The interface effect between NiSe and CNTs enhanced further π-electron delocalization of CNTs, increasing the local electron density at the Ni sites. Subsequent ionic liquids (ILs) treatment further resolved the aggregation issues of NiSe nanoparticles and carbon nanotubes, and facilitated further π-electron delocalization at the heterojunction. The imidazolium cations acted as "connectors," tightly linking the CNTs and NiSe nanoparticles. The NiSe/CNT-IL exhibited an HER overpotential of 82 mV at 10 mA cm⁻2 in 1 M KOH. Additionally, as a full water electrolysis catalyst in a water electrolyzer, it achieved a single-cell voltage of 1.965 V at a maximum current density of 500 mA cm⁻2 at 60 °C. This direct IL functionalization for CNTs facilitates the electron transfer process and ILs can serve as the electron acceptor with superior hydrogen adsorption. • The delocalization of electrons in the carbon nanotubes is enhanced, increasing the electron density near the Ni sites. • The ionic liquid improves the dispersion of carbon nanotubes. • The ionic liquid coats the catalyst surface, stabilizing catalyst particles and enhancing catalytic activity and selectivity. • The hydrophilicity of the catalyst is improved. [ABSTRACT FROM AUTHOR]

Designing a highly effective bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is a sensible approach for generating enormous hydrogen fuel by electrochemical water splitting. Herein, a high performance of ZIF-derived Co 3 S 4 on WS 2 -WO 3 electrocatalyst was developed for overall water splitting reactions. For developing the mixed phase of WS 2 -WO 3 , thioacetamide (TAA) played a crucial role as a sulfur source and acted as intercalating agent for expanding the layers of 1T WS 2 via the possible generation of NH 4 + ion. The high electrocatalytic performances is attained by the homogeneous incorporation and tunable properties of nano-sized Co 3 S 4 on WS 2 -WO 3. The electrocatalyst showed remarkable HER performance with an overpotential of only 73 mV and good OER efficiency with an overpotential of 307 mV at 10 mA/cm2. The long term chronopotentiometry and CV cycles performances convinces the stability of the electrocatalysts. A reasonable two-electrode overall water splitting performance was achieved by the WS 2 -WO 3 /Co 3 S 4 electrocatalyst in an asymmetric device, paving the path for more developments in the design and optimization of electrocatalysts for renewable energy conversion. [Display omitted] • A new kind of bifunctional electrocatalyst of ZIF-derived Co 3 S 4 on WS 2 -WO 3. • Ammonium ion intercalation promotes in increased 1T WS 2 layers. • Heterostructure interface between WS 2 -WO 3 and Co 3 S 4 expands catalytic activity. • WS 2 -WO 3 /Co 3 S 4 electrocatalyst provides excellence in HER activity. [ABSTRACT FROM AUTHOR]

The development of bifunctional electrocatalysts with high efficiency for overall water splitting is still a challenging task. In this work, we introduce a novel one-step synthesis method for Pt/NiFe layered double hydroxide (LDH) on an iron-nickel foam (INF) substrate under mild conditions. This method eliminates the need for additional Ni or Fe ions and facilitates in-situ etching and growth processes under mild conditions, resulting in a higher active surface area, well-dispersed low-loading Pt nanoparticles, and a self-supported electrode without binders. These features collectively enhance electron transfer and catalytic activity for both HER and OER. The Pt/NiFe LDH/INF exhibits remarkable water splitting performance, requiring a cell voltage of only 1.44 V at10 mA cm−2 when used as both anode and cathode. Additionally, it remains stable at 20 mA cm−2 for at least 16 h. The exceptional water splitting activity of Pt/NiFe LDH/INF in alkaline solution can be attributed to the synergistic effects of Pt and NiFe LDH, which improve the hydrogen evolution reaction and oxygen evolution reaction efficiencies. The results provide valuable insights into designing bifunctional electrocatalysts with low Pt loading for optimal water splitting performance at low operating cost. [Display omitted] • Novel one-step synthesis of bifunctional Pt/NiFe LDH electrocatalyst under mild conditions. • Excellent bifunctional HER and OER activity of the Pt/NiFe LDH/INF catalyst. • Water splitting cell voltage of 1.44 V at 10 mA cm−2 with good stability. • Enhanced water splitting performance of the low-loading Pt with NiFe LDH. [ABSTRACT FROM AUTHOR]

Amid the increasing focus on sustainable energy, hydrogen generation through photocatalysis has garnered substantial attention in recent years. Given their distinctive electronic, optical, and structural properties, two-dimensional perovskite nanosheets have surfaced as promising contenders as photocatalysts. Here we present a systematic exploration of Ruddlesden-Popper phase Ca n-1 Mn n-3 Nb 3 O 3n+1 2− (n = 4,5,6) perovskite (CMNO) nanosheets with distinct layers (n = 4, 5, and 6), synthesized via exfoliation approach, for enhanced physicochemical properties and catalytic performances. Rigorous characterizations supported by the Tauc plot and Mott-Schottky analysis reveal the crystal structures, varied bandgaps, and an n-type semiconductor behavior from the CMNO nanosheets. In a novel approach to enhance its photo-absorption, Chlorella vulgaris microalgae, strategically layered onto the CMNO nanosheets, consequently exhibit significant improvements in the onset potential and current density, especially for the CMNO (n = 6) nanosheet. This research lays a foundation for understanding the tailored composition and layer-dependent properties of CMNO nanosheets, propelling their potential application in efficient hydrogen generation through photoelectrochemical water splitting for sustainable energy technologies. • Ruddlesden-Popper phase of Ca n-1 Mn n-3 Nb 3 O 3n+1 was prepared using soft chemistry method to obtain n = 4, 5, 6 layers. • Density of States shows that n = 6 layers exhibit more bonding states than n = 4 and 5, thus contributing to photocatalysis. • Coupled with PEDOT:PSS, CMNO is layered on ITO to form a p-n junction based photoelectrode for hydrogen generation. • Chlorella vulgaris was layered on the photoelectrode to improve visible light absorption and charge-carrier separation. • The introduction of Chv on the photoelectrode significantly improves the ABPE% up to 0.15% against the control group 0.05%. [ABSTRACT FROM AUTHOR]

Despite the challenges of developing efficient photocatalysts for water splitting, we demonstrate that MgSiO 3 perovskite oxide, under applied external stress, significantly enhances photocatalytic activity. The use of earth-abundant and low-cost photocatalysts for high-efficiency photocatalytic water splitting is extremely important. Using density functional (DFT) calculations, we present increased photocatalytic water splitting activity of MgSiO 3 perovskite oxide by applying external stress. Our findings indicate that raising the concentrations of pressure can lower the lattice constants and volume of MgSiO 3. An anisotropic elastic material with high stiffness that changes from brittle to ductile at high pressure (10–30 GPa). It is stable under various circumstances owing to its high Debye temperature, thermal conductivity, and melting temperature, all of which are thermodynamic properties. MgSiO₃ is an indirect bandgap (Γ →R) p-type semiconductor with a band gap energy is 2.627 eV at 0 GPa. However, the band gap energies increase as enhanced stress is confirmed by its electronic characteristics, making it appropriate for photocatalytic water-splitting applications. Strong anisotropy, effective light absorption, and reflective properties were revealed by optical investigations, which bode well for photocatalytic applications. Moreover, the optical conductivity suggests its potential for light amplification by showing a gain behavior in the visible light region. Crucially, because of its advantageous band-edge placements, MgSiO₃ shows great promise for photocatalytic water-splitting applications. This work paves the path for more investigation into effective water-splitting technologies by demonstrating the multidimensional properties and novel and inventive nature of MgSiO 3 under high pressure, as well as by demonstrating its feasibility for a variety of photocatalytic applications. [Display omitted] • The cubic MgSiO 3 perovskite is investigated under hydrostatic pressure (0–30 GPa) for photocatalytic water splitting. • Mechanical conversion from brittle to ductile nature at high pressure (>5 GPa). • Increasing band gap by boosting the applied pressure. • Band edges play a remarkable in photocatalytic water-splitting applications. [ABSTRACT FROM AUTHOR]

The electrolytic division of water into hydrogen (H2) and oxygen (O2) presents a sustainable solution for meeting escalating demands in renewable energy sources. Yet, this process faces formidable challenges due to its energy-intensive nature. Our study introduces efficient electrocatalysts formed from chromium sulphide nanoparticles integrated with tin oxide via a straightforward solvothermal approach, enabling water splitting in both acidic and alkaline settings. The resulting SnO2@CrS2 heterostructure exhibits notable performance by requiring lower overpotentials 142 and 99 mV for achieving a current density of 10 mA cm−2 during the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 1 M KOH, and 157 and 165 mV for OER and HER in 0.1 M HClO4, respectively. Correspondingly, Tafel slopes of 30 and 45 mVdec−1 in 1.0 M KOH and 52 and 32 mVdec−1 in 0.1 M HClO4 were observed for OER and HER respectively. These catalysts display promising efficiency at reduced overpotentials, demonstrating exceptional performance for overall water splitting. This approach of integrating an active heterostructure through interfacial tuning offers a novel pathway for developing economically viable and efficient electrocatalyst systems crucial for water splitting and H2 production. Graphical abstract of synthesized catalyst [ABSTRACT FROM AUTHOR]

[Display omitted] Electrocatalytic water splitting produces green and pollution-free hydrogen as a clean energy carrier, which can effectively alleviate energy crisis. In this paper, bimetallic and selenium doped cobalt molybdate (Se-CoMoO 4) nanosheets with rough surface are resoundingly prepared. The multihole Se-CoMoO 4 nanosheets display ultrathin and rectangular architecture with the dimensions of ∼ 3.5 μm and 700 nm for length and width, respectively. The Se-CoMoO 4 electrocatalyst shows remarkable water electrolysis activity and stability. The overpotentials of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) are 270 and 63.3 mV at 10 mA cm−2, along with low Tafel slopes of 51.6 and 62.0 mV dec-1. Furthermore, the Se-CoMoO 4 couple electrolyzer merely requires a cell voltage of 1.48 V to achieve 10 mA cm−2 current density and presents no apparent attenuation for 30 h. This investigation declares that the hybridization of transition bimetallic oxide with nonmetallic adulteration can afford a tactic for the preparation of bifunctional non-precious metal-based electrocatalysts. [ABSTRACT FROM AUTHOR]

Finding an efficient photocatalyst to decompose water into hydrogen is one of the effective ways to solve the energy crisis and environmental problems. For the InN/SnS2 heterojunction,the geometric property,the electronic structure and photocatalytic properties for water splitting are explored based on first-principles calculations. The results suggest that InN/SnS2 heterostructure is a type-Ⅱ band alignment to effectively separate carriers. Under the light radiation,a narrow band gap and intrinsic electric field can accelerate the transfer of photogenerated carriers along the Z-shaped path,which preserves the strong redox ability of InN/SnS2 heterojunction. The photo-generated electrons on InN make the hydrogen evolution reaction happen continuously,while the photo-generated holes on SnS2 make the oxygen evolution reaction happen continuously. The band edge position of InN/SnS2 heterojunction can span the redox potential for the photocatalytic overall water splitting. Therefore,the results show that InN/SnS2 heterojunction is a potential direct Z-scheme photocatalyst for photocatalytic water splitting to produce hydrogen. [ABSTRACT FROM AUTHOR]

FeP/FeO was prepared on carbon cloth (CC) via hydrothermal method, heat treatment in air, and phosphorization in argon. FeP/FeO/CC presents a porous and loose morphology which is conducive to the exposure of active sites and the transfer of reactants. FeP/FeO/CC requires the low overpotentials of 257 and 117 mV (vs. reversible hydrogen electrode (RHE)) to achieve the current density of 10 mA·cm−2 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline KOH solution, respectively. The small Tafel slope values of 36.1 mV·dec−1 (for OER) and 96.2 mV·dec−1 (for HER) indicate that FeP/FeO/CC exhibits the fast electrocatalytic reactive kinetics for OER and HER. In particular, the reaction kinetics of FeP/FeO/CC accelerated with the progress of HER. The charge-transfer resistance (Rct) of FeP/FeO/CC is only 11 Ω. Excellent bifunctional electrocatalytic performances of FeP/FeO/CC should be attributed to the porous morphology and the lower charge-transfer resistance. [ABSTRACT FROM AUTHOR]

We present a compelling strategy for fabricating a hierarchical OER electrode, successively consisting of the nickel foam (NF) conductive substrate, carbon-incorporated cobalt oxide nanorod arrays, and nickel-iron hydroxide nanosheets (NF/CoO–C/NiFe–OH). Cobalt-based metal-organic framework (Co-MOF) derived porous CoO–C matrix increases electrical conductivity, facilitates charge transfer, and provides more surface sites for the NiFe–OH deposition. Furthermore, the CoO–C and NiFe–OH heterostructure alters the electronic states of active components, consequently achieving a synergistic role that promotes the OER process. The resulting NF/CoO–C/NiFe–OH exhibits prominent OER activity, with the overpotentials of 281, 347, and 466 mV at 50, 100, and 200 mA cm−2 of current densities, respectively. In the meantime, it also possesses a lower Tafel slope of 39 mV dec−1, larger electrochemical surface area, faster turnover frequencies, and lesser charge transfer resistances. Additionally, the electrode reveals superior stability without significant morphological changes and element valence states. The OER mechanism and electrochemical performance of hierarchical heterostructure regulated by nickel-iron oxyhydroxides on carbon-incorporated cobalt oxide nanorod arrays on the NF substrate (NF/CoO–C/NiFe–OH). [Display omitted] • The in-situ strategy of CoO–C/NiFe–OH hierarchical heterostructure is used. • The CoO–C matrix improves surface structure and electronic states of NiFe–OH. • The NF/CoO–C/NiFe–OH electrode has superior OER performance and durability. • The promoting mechanism of the CoO–C layer on the OER process is proposed. [ABSTRACT FROM AUTHOR]

The depletion of conventional fossil fuels necessitates the development of sustainable energy alternatives, with electrochemical water splitting for hydrogen (H 2) production being a promising solution. However, large-scale hydrogen generation is hindered by the scarcity of cost-effective electrocatalysts to replace noble metals such as Pt and RuO 2 in the Oxygen Evolution Reaction (OER) and Hydrogen Evolution Reaction (HER). In this study, we report the synthesis of CuCr 2-x In x Se 4 (x = 0, 0.2, 0.4) using a dual approach combining the Bridgman-Stockbarger method and ball milling. Among the synthesized materials, CuCr 1.8 In 0.2 Se 4 demonstrates outstanding HER activity in 1.0 M KOH, achieving a potential of −0.16 V vs. RHE at a current density of 10 mA cm−2. Moreover, the material shows remarkable durability during a three-electrode accelerated degradation test in an alkaline medium, maintaining its performance over 24 h at a constant current density of −200 mA cm−2, with a stable potential of −0.57 V vs. RHE. Additionally, CuCr 1.8 In 0.2 Se 4 was tested in a two-electrode configuration alongside CoFe LDH, achieving a benchmark of 1.7 V for overall water splitting. It sustained a current density of 400 mA cm−2 for 24 h in an accelerated degradation test, exhibiting a minimal loss of 0.1 V after the testing period. These results highlight CuCr 1.8 In 0.2 Se 4 as a promising non-noble metal catalyst for HER, demonstrating its potential to reduce reliance on noble materials for large-scale hydrogen production. [Display omitted] • CuCr 2-x In x Se 4 was synthesized using Bridgman-Stockbarger and ball milling techniques. • CuCr 1.8 In 0.2 Se 4 showed excellent HER activity, of −0.16 V vs RHE for 10 mAcm−2. • In a two-electrode setup, it required 1.7 V and to achieve 400 mAcm−2 for 24 h. [ABSTRACT FROM AUTHOR]

Due to the environmental and energy crises, scientific progress on new energy has always been highly anticipated, and how to more efficiently produce hydrogen through solar water splitting is an urgent topic. For this purpose, a two-dimensional (2D) stable In 2 Se 3 /In 2 SeTe heterojunction (HJ) is constructed and investigated by employing first-principles calculations herein. The exciton binding energy of In 2 Se 3 /In 2 SeTe is as low as ∼0.20 eV, and its conversion efficiency of solar to hydrogen (STH) for this HJ reaches 27.5%. Also, its hydrogen and oxygen evolution reactions can occur successfully without a cocatalyst. Given these characteristics, In 2 Se 3 /In 2 SeTe is a hopeful candidate for hydrogen water splitting. Moreover, for the reliability and efficiency of the exciton binding energy of 2D HJs, which strongly affects hydrogen production, the dielectric constant in the Mott-Wannier hydrogenic model should be reconsidered by including the effective thickness. In total, this manuscript not only proposes a new 2D photocatalytic material but also theoretically contributes to the Mott-Wannier hydrogenic model. We propose that In 2 Se 3 /In 2 SeTe is a water-splitting photocatalyst and finds the theoretical exciton binding energy of 2D materials is influenced by the thickness. [Display omitted] • In 2 Se 3 /In 2 SeTe demonstrates optimal band edges and robust solar energy assimilation conducive to the water dissociation process. • The electronic structure and carrier mobility contribute to enhanced charge carrier separation efficiency in In 2 Se 3 /In 2 SeTe. • The solar conversion efficiency of In 2 Se 3 /In 2 SeTe reaches up to 27.5%, underscoring its economic feasibility. • Both oxygen and hydrogen generation in In 2 Se 3 /In 2 SeTe can be achieved without the need for a cocatalyst. • The effective thickness of 2D materials is suggested be included in the Mott-Wannier hydrogenic model. [ABSTRACT FROM AUTHOR]

In this study, Co-bearing Metal-Organic Frameworks (MOFs) are grown via a facile solvothermal process on the surface of two kinds of conductive substrates – titanium dioxide nanotubes (TiO 2 NT) and fluorine-doped tin oxide (FTO) glass and tested as electrodes in the electrochemical hydrogen evolution reaction (HER). The materials derived from three organic linkers - terephthalic acid (Co-BDC), 2-aminoterephthalic acid (Co-BDCNH 2), and trimesic acid (Co-BTC) are characterized by FTIR, Raman, XRD, SEM-EDS, BET, and XPS. Among the layers on FTO without post-synthesis treatment, Co-BTC shows the highest activity (overpotential of HER 1.72 V vs. Ag/AgCl/KCl). The effects of substrate change on TiO 2 NT and annealing of Co-BTC layers in air and argon on their electrocatalytic properties are also studied. Using TiO 2 nanotubes as a substrate and annealing the material in air results in a reduction of the hydrogen evolution overpotential to 1.44 V vs. Ag/AgCl/KCl and a significant reduction in the exchange current density. • Co-based MOFs were successfully fabricated on FTO and TiO 2 NT. • Electrochemical activity depended more on organic linker than substrate type. • Annealing of Co-BTC materials improves catalytic activity in HER. [ABSTRACT FROM AUTHOR]

The preparation of high-efficiency electrocatalysts for the oxygen and hydrogen evolution process (OER and HER) using an easy, green, and facile preparation method is crucial for the effective and economical use of clean energy sources. We report here an eco-friendly phytic acid (PA)-assisted phosphidation strategy to synthesize a novel Cu 3 P decorated on N-doped carbon (Cu 3 P-NC). Its synthesis involves precipitation of rode-like microstructured Cu-based aspartic acid frameworks (Asp-Cu MOF), chemical etching of Asp-Cu MOF to form PA cross-linked Cu complexes, and a final pyrolysis step to get Cu 3 P-NC with abundant Cu 3 P nanoparticles loaded on N-doped carbon matrix. The Cu 3 P-NC catalyst demonstrates catalytic performances with low overpotentials of 116 and 310 mV at 10 mA cm−2, small Tafel slopes of 61.2 and 69.2 mV dec−1, for HER and OER respectively, and high catalytic durability in 1 M KOH. The as-prepared Cu 3 P-NC electrocatalyst offers a new viewpoint on developing multi-functional electrocatalysts in the water-splitting process using environment-friendly substances such as amino acids. [Display omitted] • The Cu 3 P-NC is fabricated as promising electrocatalyst in OER and HER. • The synergistic effect among Cu 3 P NPs and NC improves electrical conductivity. • The Cu 3 P-NC exhibits a favorable prospect for development of electrocatalysts based on amino acids. [ABSTRACT FROM AUTHOR]

A sugarcane molasses, a promising source of polysaccharides, was used in this study in order to modify the size, shape orientation, surface area, and charge transport properties of Co 3 O 4 nanostructures. Several methods have been used to obtain structural information on nanostructures, including powder X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible spectrometry, and Fourier transform infrared spectroscopy (FTIR). Furthermore, cyclic voltage measurements (CV), linear sweep voltage measurements (LSV), galvanostatic charge-discharge measurements (GCD), and electrochemical impedance measurements (EIS) were performed on Co 3 O 4 nanostructures in conjunction with various electrochemical measurements. The major contribution of this study was focused on the development of an asymmetric supercapacitor using Co 3 O 4 nanostructures. The oxygen evolution reaction (OER) activity of Co 3 O 4 nanostructures was investigated in an aqueous solution containing 1 M KOH, and an asymmetric supercapacitor was tested in an electrolyte containing 3 M KOH. An optimal Co 3 O 4 nanostructure with OER activity has an overpotential of 330 mV at 10 mA cm−2 and a Tafel slope of 92 mVdec−1. The optimized Co 3 O 4 nanostructure demonstrated excellent durability during OER activity for 40 h. Among the three electrode-based supercapacitors, sample 1 had the highest specific capacity with 1070C/g, the highest capacitive retention percentage at 100%, and the highest columbic efficiency at 101%. Thus, ASC devices based on optimized Co 3 O 4 nanostructures exhibit exceptional specific capacities of 301C/g and 6.4 Wh/Kg at 1.5A/g. The retained capacitance was observed to be 99% after 40000 galvanostatic charge-discharge cycles (GCD). The transformation of Co 3 O 4 nanowires into nanoparticles having large specific surface area were synthesized in the sugarcane molasses and their enhanced electrochemical performance was demonstrated. [Display omitted] • Sugarcane molasses was used to synthesize functional Co 3 O 4 nanostructures. • Electrochemical performance of Co 3 O 4 nanostructures was highly improved. • An overpotential of 330 mV was noticed at 10 mAcm−2 during water oxidation. • Asymmetric supercapacitor exhibited specific capacity of 310C/g. [ABSTRACT FROM AUTHOR]

Water electrolysis is one of the recent alternatives for the generation of clean fuels (Hydrogen) with no unwanted by-products. As primary energy sources, hydrocarbon-based fuels harm the environment due to greenhouse gas emissions. Researchers all over the globe have been working hard to make it economically viable. Despite the development of several water-splitting electrocatalysts, effective material catalysts with enhanced activity, specificity, and durability are still missing. Noble metals may be replaced with transition metal-based catalysts. Among them, copper sulfide is one of the significant electrocatalysts for water splitting. Because of its unique structural and electrochemical features, copper sulfide compounds reduced toxicity and developing material has a lot of potential in electrochemistry. The interpretations of CuS heterojunctions will also facilitate the productive and safe preparation of high-quality electrode materials for high-energy storage devices. In this article, we have discussed the significance of Copper sulfide-based heterojunctions as efficient electrocatalysts, including HER, OER, CO 2 reduction and ORR. Copper sulfide-based heterojunctions for supercapacitors (SCs) and Lithium-ion batteries (LIBs) are also comprehensively discussed. This paper discusses the structural and electrochemical properties of CuS, its nanocomposites, and the methods used for their production. This discussion examines the relationship between these characteristics and the criteria for electrocatalysts in the process of total water splitting and its related reactions. Consequently, this paper lays forth a plan for future research into green energy generation and storage using electrochemical materials that are efficient, safe for the environment, and financially feasible. • Focus on recent progress in copper sulfide-based nanocomposites for water splitting. • Advantages of CuS nanocomposites/nanostructures for water splitting are highlighted. • Mechanisms of OER, HER and Water splitting are systematically illustrated. • Applications of copper sulfide nanomaterials for ORR and CO 2 reduction are also discussed. • Applications of copper sulfide nanomaterials for energy storage are also highlighted. • Suggestions on further development of electrochemical and energy storage materials. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) are emerging as efficient oxygen evolution reaction (OER) electrocatalysts due to their structural advantages and compositional flexibility. Despite their promise, Mn-based LDHs are hampered by poor conductivity, limiting their OER efficacy. This research introduces a hydrothermal and chemical etching technique to fabricate NF/NiMn LDH@NiMnFe(OH) x structures, significantly improving OER performance. The study reveals that integrating Fe3+ into the NiMn LDH fosters a synergistic Ni–Fe interaction, markedly boosting electrocatalytic efficiency. The NF/NiMn LDH@NiMnFe(OH) x -90 shows a low overpotential of 250 mV at 10 mA cm−2 and a Tafel slope of 49.9 mV dec−1 in 1 M KOH, surpassing both its NM precursor and other Ni-based LDH catalysts, including commercial RuO 2. In situ, Raman spectroscopy indicates a pivotal phase transition in NF/NiMn LDH@NiMnFe(OH) x to NiOOH at elevated potentials, essential for OER activity. Raman peaks at 463 and 585 cm−1 confirm this structural evolution. The OER activity boost is attributed to increased oxygen vacancies and enhanced conductivity. Moreover, NF/NiMn LDH@NiMnFe(OH) x -90 maintains stability with negligible degradation after 24 h, underscoring its durability. These findings offer a strategic approach to designing high-performance OER electrocatalysts, leveraging nickel-based layered double-metal oxides for potential water-splitting applications, and emphasize the significance of surface engineering and compositional tuning. • The catalyst with high activity and stability was constructed by a simple method. • Important insights for the design of heterophase electrocatalysts is proposed. • In situ Raman reveals key phase transition to NiOOH at elevated potential. • Fe etching increases oxygen vacancy and conductivity, thus increasing OER performance. [ABSTRACT FROM AUTHOR]

Confronted with the pressing issue of energy scarcity, the development of an economical and potent bifunctional catalyst is of paramount importance. We adopt an interface engineering strategy to modify the surface of NiFe‐LDH nanoplates with O2 plasma treatment. This process enhances the local electric field of NiFe‐LDH, resulting in the formation of a self‐assembled polycrystalline nanowire array on the nanoplate surface. After O2 plasma treatment for 30 min, the NiFe‐LDH‐P30 not only formed a heterostructure with rough surface, but also regulated the exposure of crystal surfaces. Due to the strong interface coupling between the self‐assembled 3D nanoflowers, 2D nanoplates and 1D nanowires, the NiFe‐LDH‐P30 exhibits an excellent structural stability. Moreover, it demonstrated exceptional HER and OER activities in alkaline condition, achieving a low overpotentials of 154 mV and 242 mV at 10 mA cm−2, respectively. Furthermore, NiFe‐LDH‐P30 as the dual‐electrode material for the cathode and anode in the process of water splitting results in a low voltage of 1.63 V at a current density of 10 mA cm−2. Through the strategic application of interface engineering, this work has pioneered a novel approach to the creation of transition metal‐based electrocatalysts, which is benefit to a range of practical energy applications. [ABSTRACT FROM AUTHOR]

The development of electricity‐driven oxygen evolution reaction (OER) is a potent solution for energy storage applications. In recent years, there is a surge in interest in designing transition metal‐based catalysts with stable linkages, presenting an efficient alternative to noble metal‐based electrocatalysts. Transition metal complexes linked by salen ligands garner considerable attention due to their capacity to chelate and stabilize metal ions. This work presents a novel approach by strategically incorporating the metal–salen core into a porous organic polymer (POP) backbone, thereby fabricating a highly effective electrocatalyst for oxygen evolution. The judicious selection of metal–salen active sites, coupled with the intramolecular free volume (IMFV) of the triptycene core and the high specific surface area of the salen–POPs, result in superior OER activity. By precisely tuning the structure through variation of the transition metal in the salen unit, deep insights are gained into their electrocatalytic behavior. Notably, the most efficient catalyst, Ni‐DHDA‐TAT, exhibits an impressively low overpotential (η10) of ≈ 270 mV at a current density of 10 mA cm−2 for OER (in 1 m KOH). Further, Ni‐DHDA‐TAT retains its activity even after 50 h of chronoamperometry and 1000 cyclic voltammetry cycles with negligible degradation in its initial performance. [ABSTRACT FROM AUTHOR]

The development of a catalyst exhibiting outstanding catalytic activity and robust stability for both the oxygen evolution reaction and hydrogen evolution reaction in alkaline media represents a substantial challenge. In this work, a NF/Ni@NiCoSP heterostructure bifunctional catalyst was developed via a sequent process of electrodeposition-hydrothermal-low temperature thermal pyrolysis sulphuration/phosphorization. The physical characterizations reveal that the as-prepared sample of NF/Ni@NiCoSP exhibits a porous nano-needles array structure and consists of both Ni 3 S 2 and Co 2 P phases with considerable boundaries. As a consequence, the NF/Ni@NiCoSP presents an ultralow overpotential of 47 mV and 260 mV at 10 mA cm−2 for hydrogen evolution reaction and oxygen evolution reaction, respectively. When assembled to a two-electrode system, it only requires 1.53 V to reach 10 mA cm−2, which surpasses the commercial RuO 2 ‖Pt/C (1.61 V). The methanol oxidation reaction probing experiment suggests the easy desorption of ∗OH from active sites due to the decreased binding strength between ∗OH and the catalyst, thus optimizing the kinetics condition. Moreover, the in-situ Raman spectra reveal that NiOOH and CoOOH serve as active sites for OER while the metal sites for HER. Therefore, this work introduces a feasible strategy to design cost-effective and robust catalysts with excellent catalytic properties, thereby paving the way for water splitting. • MOR probing experiment suggesting the easy desorption of ∗OH from active sites. • The NiOOH and CoOOH serve as active site for OER while the metal sites for HER. • NF/Ni@NiCoSP heterostructure bifunctional catalyst was developed. [ABSTRACT FROM AUTHOR]

The design of high-efficiency and cost-effective electrocatalysts for water splitting has recently received much attention. Herein, a self-supported Fe-doped NiMo/NiCo bifunctional electrocatalyst was synthesized using hydrothermal method on nickel foam (NF) to enhance both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). SEM observations revealed NiCo microspheres arranged in a flower-like structure, with Fe-doped NiMo rods decorating the surface. This electrocatalyst demonstrated impressive HER performance, requiring a low overpotential of 63 mV, versus reversible hydrogen electrode (RHE), at a cathodic current density of −10 mA/cm2, and a small charge transfer resistance (R ct) of 2.43 Ω at −200 mV (RHE). For OER, the synthesized electrocatalyst revealed excellent activity, with a low overpotential of 151 mV (RHE) to afford an anodic current density of 10 mA/cm2 and a small R ct of 0.43 Ω at 300 mV (RHE). Meanwhile, the Fe-doped NiMo/NiCo@NF electrocatalyst in a two-electrode configuration needed only a cell voltage of 1.53 V to deliver a current density of 10 mA/cm2. Overall, this work disclosed that the combination of NiCo and NiMoFe results in the synthesis of a heterogeneous electrocatalyst that offers high efficiency for water splitting and maintains good stability over 10 h. [Display omitted] • A hierarchical Fe-doped NiMo/NiCo@NF electrocatalyst, was synthesized by the hydrothermal method. • Large specific surface area, abundant active sites, and synergistic effects between constituents enhanced both HER and OER activity. • This electrocatalyst displayed appropriate structural and performance stability for10 h. [ABSTRACT FROM AUTHOR]

Herein, we report the impact of external perturbation on the photocatalytic performance of g-C 3 N 4 /CoN 4 heterojunction and concomitant transition from type-I to type-II. The state-of-the-art theoretical modeling presented here is the first study on dynamic role of strain and electric field on g-C 3 N 4 /CoN 4 heterojunction and its potential application as a solar-driven water splitting reaction. Utilizing the density functional theory (DFT) calculation, V. N. et al. recently reported the photocatalytic activity of g-C 3 N 4 /MN 4 (M = Mn, Fe and Co) heterojunction [J. Comput. Chem. 2024 , 45 , 2518-2529, https://doi.org/10.1002/jcc.2746412 ] and subsequently established g-C 3 N 4 /CoN 4 as a type I heterojunction for photocatalytic water splitting reaction [Phys. Chem. Chem. Phys. 2024 , 26 , 21117–21133]. In the present study, we applied external perturbation in the form of mechanical strain, electric field and evaluated the electronic structure properties of the system along with the detailed examination of concomitant optical and magnetic properties of g-C 3 N 4 /CoN 4 heterojunction. The switching of photocatalytic feature from type I to type II originates due to the crossover between valence band maxima (VBM) of g-C 3 N 4 and CoN 4 in presence of external perturbation. Notably, the resulting system acts as a type II photocatalyst for water splitting reaction while applying compressive (negative) strain of −2 to −6% and an electric field of −0.5 and +0.5 V/Å, respectively. Accumulation of photogenerated electrons and holes separately in g-C 3 N 4 and CoN 4 units confirms the perceptible separation of charge carriers and thereby reduces the recombination compared to un-perturbed system. A red-shifted absorption maximum (689 nm), superior charge transfer (0.9e), and clear separation of photogenerated electrons and holes are the origin of enhanced photocatalytic efficiency of g-C 3 N 4 /CoN 4 heterojunction in the presence of external perturbation. We believe that our work will provide enough evidence to the experimentalists to achieve such a system in practice leading to human-friendly applications. Type II g-C 3 N 4 /CoN 4 heterostructure fabricated by an external perturbation strategy for efficient photocatalytic water splitting reaction. [Display omitted] • Density Functional Theory. • Theoretical Modelling of g-C 3 N 4 /CoN 4 heterojunction in presence of biaxial strain and electric field. • Photocatalyst for water splitting reaction. • Valence band crossover of g-C 3 N 4 and CoN 4 units. • Enhanced efficiency of solar energy conversion within the visible spectrum. [ABSTRACT FROM AUTHOR]

The advancement of energy storage and conversion technologies critically depends on developing superior electrode materials characterized by high specific capacitance and exceptional electrocatalytic properties. In this study, we successfully synthesized a novel ZnCo 2 O 4 @NiCo-LDH nanoelectrode material using the hydrothermal method. This composite exhibited an impressive specific capacitance of 1118 C g−1 at a current density of 1 A g−1. The resulting supercapacitor demonstrated a high energy density of 15.56 μWh cm−2 at a power density of 0.825 mW cm−2. Notably, after 10000 cycles, the material retained 79.7% of its initial capacity, underscoring its substantial cyclic stability and potential for supercapacitor applications. Furthermore, the ZnCo 2 O 4 @NiCo-LDH material displayed excellent electrocatalytic properties, with an overpotential of 54.2 mV for the Hydrogen Evolution Reaction (HER) at a current density of 10 mA cm−2 and a Tafel slope of 48.69 mV dec−1. For the Oxygen Evolution Reaction (OER), it showed an overpotential of 296.1 mV and a Tafel slope of 24.13 mV dec−1. These results indicate that the ZnCo 2 O 4 @NiCo-LDH nanoelectrode material is highly promising for high-performance supercapacitors and electrocatalytic water splitting applications, paving the way for new developments in energy storage and conversion technologies. • Composite: High specific capacitance of 1118 C g−1 at 1 A g−1 current density. • Supercapacitor: 15.56 μWh cm−2 energy density at 0.825 mW cm−2 power density. • For HER, the overpotential is 54.2 mV with a Tafel slope of 48.69 mV dec−1. • For OER, the overpotential is 296.1 mV with a Tafel slope of 24.13 mV dec−1. • ZnCo 2 O 4 @NiCo-LDH: High performance for supercapacitors and water splitting. [ABSTRACT FROM AUTHOR]

Green hydrogen will play an important role in reducing carbon emission in sectors like transportation, power supply, and industry. However, for it to become competitive technology, the costs related to hydrogen production must be reduced. Photocatalytic hydrogen production is one of the green hydrogen production methods that have the potential to become cost effective. So far, photocatalytic water splitting has mainly focused on hydrogen production from pure water systems, but it is practically attractive to study methods for seawater systems, which will make better use of available natural resources. In this study, we focus on the synthesis and characterization of a variety of metal dichalcogenide-embedded titanium dioxide (NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2) nanocomposite materials as photocatalysts for seawater splitting. The materials were synthesized using a facile hydrothermal method and were used for simulated seawater, seawater and deionized water splitting with 4 h of simulated solar illumination. The amounts of 48.11, 24.94, 15.04, and 2.78 mmolg−1 hydrogen were successfully produced with NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2, and pristine TiO 2 nanomaterials, respectively. Highest amount of H 2 with NiS 2 /TiO 2 photocatalyst can be attributed to the low bandgap of NiS 2, which acts as a co-catalyst. Our study clearly demonstrates that low-cost, noble-metal-free nanocomposite photocatalysts could be promising candidates for realizing efficient solar-to-hydrogen conversion from seawater splitting. • -NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2 - nanocomposite materials were synthesized for photocatalytic water splitting in seawater, simulated seawater and deionized water using a facile hydrothermal method. • 48.11, 24.94, and 15.04 mmol/g of hydrogen were obtained with NiS 2 /TiO 2 , CoS 2 /TiO 2 , SnS 2 /TiO 2 nanomaterials in seawater. • Highest photocatalytic activity with metal chalcogenide-embedded titanium dioxide can be attributed to the low bandgap of metal chalcogenide material, which acts as a co-catalyst. • This study clearly demonstrates that low-cost, noble-metal-free nanocomposite photocatalysts could be promising candidates for realizing efficient solar-to-hydrogen conversion from seawater splitting. [ABSTRACT FROM AUTHOR]

The FeTiO 3 nanopowder is a vital engineering material known for its exceptional performance in energy generation, storage, electrochemical sensors, and catalysis. However, synthesizing FeTiO 3 nanopowder with high crystallinity and phase purity typically requires specialized equipment and controlled heat treatment due to the instability of Fe2+ ions. Using the one-step solution combustion synthesis (SCS) method, FeTiO 3 nanopowder withe high crystallinity were successfully produced utilizing basic equipment. Additionally, the influence of carbon additives on phase transitions, as well as the physical and physicochemical properties of the synthesized powder, was examined. XRD results indicate that increasing the amount of fuel, particularly glycine, creates a stable environment for the crystallization of FeTiO 3 nanoparticles. Moreover, enhancing the carbon content in precursor solutions with urea enhances reduction conditions and boosts the stability of FeTiO 3 in the final product. The presence of carbon additives in glycine-fuel samples leads to unfavorable outcomes by increasing the levels of TiO 2 and Fe 3 O 4 undesirable phases. Incorporating additive carbon into the urea-synthesized precursor solution resulted in a particle size increase exceeding 50 nm and raised the combustion temperature by a minimum of 230 °C. Furthermore, the presence of 15 wt% additive carbon in the sample synthesized with glycine improved the specific surface area of particles from 2.44 m2/g to 18.41 m2/g. Obtained results have shown that achieving high crystallinity of FeTiO 3 nanopowder is feasible through a one-step solution combustion synthesis process. This can be accomplished by carefully choosing the synthesis conditions, such as the type and quantity of fuel, along with the carbon additive. [ABSTRACT FROM AUTHOR]

The efficiency of catalysts relies on comprehending the underlying kinetics that govern their performance. Under the steady‐state regime, the "rate" is referred to as the turnover frequency, where the reaction rate is first order with respect to catalysts. Here, we introduce the Maximum Kinetic Efficiency (MaxKinEff) model, grounded in collision theory, to predict efficiency based on maximum turnover frequency, ΓmaxTOF0 ${{\rm{\Gamma }}_{max\;TOF}^0 }$ and maximum turnover number, τmaxTON0 ${\tau _{max\;TON}^0 }$. The model was applied to molecular water oxidation using twenty‐six transition metal catalysts from the first (3d), second (4d), and third (5d) rows. A thorough investigation reveals that [Ru(pda)(Br‐py)2] (pda=1,10‐phenanthroline‐2,9‐dicarboxylate; Py=pyridinophane) exhibits a notable ΓmaxTOF0 ${{\rm{\Gamma }}_{max\;TOF}^0 }$ of 1176.87×10−5 s−1 due to its larger collision diameter (σRC) and lower activation energy (Ea). Importantly, the trend in the computed τmaxTON0 ${\tau _{max\;TON}^0 }$ values aligns with experimental TON, τexperimentalTON0 ${\tau _{experimental\;TON}^0 }$ validating the model's accuracy. For instance, [Cp*Ir(κ2‐N,O)NO3] is identified by MaxKinEff as a standout performer, with the normalized maximum computed TON, τmaxTON0 ${\tau _{max\;TON}^0 }$ resembling the experimental TON, τexperimentalTON0 ${\tau _{experimental\;TON}^0 }$ =2000. [ABSTRACT FROM AUTHOR]

The development of an efficient, low‐cost and earth‐abundant electrocatalyst for water splitting is crucial for the production of sustainable hydrogen energy. However their practical applications are largely restricted by their limited synthesis methods, large overpotential and low surface area. Hierarchical materials with a highly porous three‐dimensional nanostructure have garnered significant attention due to their exceptional electrocatalytic properties. These hierarchical porous frameworks enable the fast electron transfer, rapid mass transport, and high density of unsaturated metal sites and maximize product selectivity. Here the process involved obtaining monodispersed microrod‐shaped Ni(OH)2 through a hydrothermal reaction, followed by a heat treatment to convert it into hierarchical microrod‐shaped NiO materials. N2 sorption analysis revealed that the BET surface area increased from 9 to 89 m2/g as a result of the heat treatment. The hierarchical microrod‐shaped NiO materials demonstrated outstanding bifunctional electrocatalytic water splitting capabilities, excelling in both HER and OER in basic solution. Overpotential of 347 mV is achieved at 10 mA/cm2 for OER activity, with a Tafel slope of 77 mV/dec. Similarly, overpotential of 488 mV is achieved at 10 mA/cm2 for HER activity, with a Tafel slope of 62 mV/dec. [ABSTRACT FROM AUTHOR]

The photocatalytic hydrolysis reaction primarily unfolds on the material's surface, making the material's morphology and microstructure critical for the catalytic efficiency of photocatalysts. In this paper, a formic acid-assisted melamine hydrothermal self-assembly method is explored to prepare g-C 3 N 4 photocatalysts with a unique morphology. The impact of sintering temperature on the morphology of the g-C 3 N 4 photocatalysts are explored and the effect of formic acid concentration on the XRD and FTIR was analyzed. Findings reveal that the g-C 3 N 4 nanostructures photocatalyst possesses fibrous tubular and nanosheet structures, boasting a heightened specific surface area (32.9 m2/g) and a more refined graphite-like crystalline framework. When synthesized with a 0.15 M concentration of formic acid, the g- C 3 N 4 nanostructured photocatalyst achieved a hydrogen production rate (1289.4 μmol h−1 g−1), which is approximately 4.8 times greater than that of bulk g-C 3 N 4 (264.7 μmol h−1 g−1). This work provides a simple method for preparing high-performance g-C 3 N 4 based photocatalysts for visible light hydrolysis hydrogen production. [ABSTRACT FROM AUTHOR]

The synthesis of hydrogen via water electrolysis is an important step towards resolving the energy crisis and impeding global warming, as hydrogen can be used as a green energy carrier. The oxygen evolution as one half‐cell reaction (OER) is currently limiting efficient water splitting due to kinetic inhibition as well as a complex mechanism, causing a large overpotential. Nickel‐iron layered double hydroxides (LDH) were found to be suitable OER catalysts, as they are cost effective, stable and highly active. This work focuses on the intercalation of different organic and inorganic borates into the LDH interlayers to study their influence on OER. Besides activity and stability measurements, three borate candidates were chosen for a kinetic study, including steady‐state Tafel analysis and reaction order plots. It was found that the Bockris pathway with the second step as rate‐determining step was predominant for all three catalysts. Of all candidates, the intercalation of borate resulted in the highest performance, which was associated with a high reducibility affecting the active metal sites. [ABSTRACT FROM AUTHOR]

Photoelectrocatalysis has attracted significant attention for water splitting and contaminant degradation. However, the lifetime of photoelectrocatalysis devices is hampered by the severe instability and photocorrosion of the photo‐active nanomaterial on the photoelectrode, which is a key limitation to realizing industrialization. Typically, the conventional protection strategy of photoelectrodes usually suffers from the trade‐off between the photoelectrocatalytic activity and stability. Inspired by biological cell membrane with water channels, here a highly permeable and ultrathin silica coating with ultrasmall straight nanochannels is in situ grown that stabilizes the photoelectrode. These ultrasmall channels boost photoelectrocatalysis by accelerating water transport and reducing the reaction energy within the confined nanochannels. Specifically, the ultrathin coating imparts significant mechanical and structural stability to the photo‐active nanomaterial, thereby preventing its detachment, dissolution, and crystal damage without compromising performance. As a result, the protected photoelectrode exhibits enhanced water splitting activity and excellent stability over 120 h, whereas the photocurrent of the unprotected photoelectrode degrades rapidly. Meanwhile, the coated photoelectrode also exhibits superior photoelectrocatalytic degradation efficiency (>97%), even after the 10th cycle. This strategy is facile and universal and can be extended to construct other stable and high‐performance electrodes for promoting photoelectrocatalysis in practical applications. [ABSTRACT FROM AUTHOR]

Engineering metal‐oxygen (M‒O) interactions for catalyzing oxygen evolution reaction (OER) by tuning the coordination geometry of metal sites is crucial for improving catalytic performance, which remains unexplored, especially in structurally diverse phosphate‐based catalysts. Herein, two NaCoPO4 (NCP) polymorphs with distinct metal coordinations: orthorhombic‐Pnma (CoO6) and hexagonal‐P65 (CoO4) denoted as O‐NCP and H‐NCP, respectively are synthesized through unique quenching‐based synthesis, to investigate the impact of coordination geometry on M‒O covalency and OER performance. The CoO4 (H‐NCP) polymorph delivered superior OER activity with low overpotential at 10 mA cm−2 (η10 = 303 mV) and long‐term stability than CoO6‐based O‐NCP. Spectroscopic and computational studies linked the superior activity of CoO4 to higher Co‒O covalency, enhanced metal electronic states near the Fermi level, and improved electrochemical reconstruction. Further, M‒O covalency regulated OER mechanism, where high‐covalent CoO4 follows conventional concerted proton‐electron transfer pathway, while CoO6 entails a non‐concerted pathway, where the lattice oxygen participation remains unfavorable due to downshifted O 2p band center. Further, OER‐active tetrahedral metal is demonstrated in a high‐entropy catalyst requiring lower η10 of ≈284 mV. This study unlocks a unique strategy for designing next‐generation OER catalysts with superior activity and durability, harnessing the interplay between metal coordination and metal‐oxygen covalency. [ABSTRACT FROM AUTHOR]

In this study, nanocomposites of g‐C3N4/MN4 (where M is Mn, Fe and Co) have been designed using advanced density functional theory (DFT) calculations. A comprehensive analysis was conducted on the geometry, electronic, optical properties, work function, charge transfer interaction and adhesion energy of the g‐C3N4/MN4 heterostructures and concluded that g‐C3N4/FeN4 and g‐C3N4/CoN4 heterojunctions exhibit higher photocatalytic performance than individual units. The better photocatalytic activity can be attributed mainly by two facts; (i) the visible light absorption of both g‐C3N4/FeN4 and g‐C3N4/CoN4 interfaces are higher compared to its isolated analogs and (ii) a significant enhancement of band gap energy in g‐C3N4/FeN4 and g‐C3N4/CoN4 heterostructures limited the electron–hole recombination significantly. The potential of the g‐C3N4/MN4 heterojunctions as a photocatalyst for the water splitting reaction was assessed by examining its band alignment for water splitting reaction. Importantly, while the electronic and magnetic properties of MN4 systems were studied, this is the first example of inclusion of MN4 on graphene‐based material (g‐C3N4) for studying the photocatalytic activity. The state of the art DFT calculations emphasis that g‐C3N4/FeN4 and g‐C3N4/CoN4 heterojunctions are half metallic photocatalysts, which is limited till date. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is a promising avenue to produce green hydrogen for future sustainable development. Developing multifunctional catalysts with high-performance toward urea oxidation reaction (UOR) and oxygen evolution reaction (OER) offers a unique approach for simultaneously achieving the degradation of urea-containing wastewater and energy-saving hydrogen production. Ni-based materials are a kind of promising materials for electrocatalysis, since its abundant reserve and tolerance. However, low intrinsic activity and catalytic efficiency hinder its wide application. Here, a defect engineering strategy is developed to create vacancies on NiAl layer double hydroxides (LDHs) catalysts by selectively etching Al ions in strong alkaline solution. The obtained NiAl LDHs with rich defects (D-NiAl LDHs) exhibit good OER performance with overpotential of 264 mV to achieve a current density of 10 mA cm−2 and a Tafel slope of 39.8 mV dec−1. In addition, the D-NiAl LDHs catalysts also show excellent UOR activity using a potential of 1.328 V vs. RHE @ 10 mA cm−2 in alkaline solution. In comparation to NiAl LDHs, the enhanced performance of D-NiAl LDHs toward oxidation of small-molecule OH− and urea could be attributed to electronic regulation of defects and a larger electrochemical surface area. Partially replacing the OER with the UOR, the driving voltage of overall water splitting reduces effectively from 1.856 V to 1.688 V at a current of 100 mA cm−2. • The D-NiAl LDHs was fabricated by selective etching Al atoms of NiAl LDHs. • The influence of defects on electron structure and performance of OER and UOR. • The D-NiAl LDHs exhibits outstanding performance toward urea-replace water splitting. [ABSTRACT FROM AUTHOR]

Ablation of well-defined nanostructures from continuous metal-sites leaching during catalysis is the cause of decreased catalytical activity/durability restricting the scale-up application in industry. Thus, it is essential to throw in-depth insight into the principle of metal-sites dissolution and structural features to tailor catalytical kinetics/stability. Considering layered double hydroxides (LDH) are haunted by unsatisfactory long-term catalytical stabilities, we lay emphasis on the nanostructure design of micrometer-scale-lateral-size CoFe LDH (1–3 μm) with embeddedness of low-crystallinity nickel hydroxides (LC-Ni(OH) 2 /CoFe LDH). Strong in-situ Ni leaching of LC-Ni(OH) 2 /CoFe LDH during catalysis enables the improved surface roughness and transition metal-site stabilization of CoFe LDH counterpart with optimized metal-oxygen covalency for stable ultrahigh-current (1000 mA cm−2) water oxidation. LC-Ni(OH) 2 /CoFe LDH exhibits excellent oxygen evolution reaction (OER) performance requiring only 270 mV overpotential to drive the current density of 100 mA cm−2 in 1 M KOH. More impressively, for 1000 mA cm−2, its overpotential is only 346 mV with stable OER operation for 68 h. Density functional theory calculations reveal that the larger formation energy of oxygen vacancy in LC-Ni(OH) 2 /CoFe LDH inhibits the release of lattice O during OER catalysis, resulting the LC-Ni(OH) 2 /CoFe LDH excellent catalytical stability. This distinctive "corrosion-to-stabilization" perspective not only challenges the general belief that metal-site dissolution diminishes active phase to weaken the operation stability but also notably improves catalytic ability of LDH guiding practical catalysts design for commercial water splitting. • Large oxygen-vacancy formation energy during catalysis was achieved. • Inhibiting lattice-O release of CoFe LDH for OER renders high catalytical stability. • Low crystallinity Ni(OH) 2 was controllably embedded into CoFe LDH nanosheet. [ABSTRACT FROM AUTHOR]

The exploration of high-performance water electrolysis catalysts is crucial for the development of hydrogen energy and the alleviation of increasingly serious environmental problems. Transition metal phosphonates are very promising electrocatalysts. In this work, a new nickel phosphonate has been synthesized and successfully developed into high-performance electrocatalyst through in-situ growth on nickel foam (NF), introduction of iron, and adjustment of Ni:Fe mole ratio. It is revealed that NiFe12 and NIFe13 exhibit the best OER (η 10 : 268 mV vs. RHE; Tafel slope: 54 mV dec−1) and HER (η 10 : 172 mV vs. RHE; Tafel slope: 77 mV dec−1) catalytic activity under optimized conditions, respectively, with fast reaction kinetics and long-term durability. The water electrolysis device assembled with them can drive a current density of 10 mA cm−2 at low voltage (1.68 V) with long-term durability, demonstrating promising application prospects. This work has important reference significance for the development of transition metal-based water electrolysis catalysts. [Display omitted] • A nickel phosphonate with two-dimensional crystal structure has been synthesized. • Nickel phosphonate can be developed into high-performance electrocatalyst. • The nickel phosphonate is in situ grown on nickel foam and doped with iron. • The OER and HER performance can be optimized by finely altering the Ni:Fe ratio. • Transition metal phosphonates are very promising electrocatalysts. [ABSTRACT FROM AUTHOR]

The development of efficient catalysts for electrochemical water splitting has become a significant contemporary challenge. Transition metal oxides, due to their unique electrochemical properties, have emerged as promising candidates. Among these, a group of BiMeVO x -based compounds shows particular potential for practical applications in hydrogen and oxygen evolution reactions. However, improvement is still necessary to achieve stable operation of these catalysts in green hydrogen generation. With this is mind, in this study we synthesize BiMeVO x materials with graphene addition using a simple annealing in a tube furnace and investigate their electrochemical properties in HER and OER. After incorporating different metals into the BiMeVO x structure, we observed variations in electrochemical properties; materials with the addition of molybdenum and cobalt (BiMoVO x and BiCoVO x) outperformed materials containing zirconium and cerium (BiZrVO x and BiCeVO x). The BiMoVOx/C catalyst showed excellent HER performance with an overpotential of 432 mV at 10 mA/cm2 and a Tafel slope of 76 mV dec⁻1, while BiCoVOx/C exhibited superior OER activity with a Tafel slope of 100 mV dec⁻1, lower than that of commercial IrO₂. The addition of graphene improved the conductivity and overall activity of the catalysts. These findings indicate that metal doping and graphene incorporation are effective strategies for enhancing the performance of BiMeVOx-based materials in water splitting applications. [Display omitted] • The addition of molybdenum and cobalt to the BiMeVO x structure improve the electrochemical properties. • Graphene was found to contribute to increased sample conductivity and catalyst activity. • The addition of molybdenum and graphene in BiMoVOx/C increased activity in HER with an overpotential at 432 mV. • The addition of cobalt and graphene in BiCoVOx/C improved catalytic performance with the Tafel slope a 100 mV dec−1. [ABSTRACT FROM AUTHOR]

In this study, we utilized interfacial engineering to modify the surface interface of the material via interfacial hydrolysis reaction at room temperature to establish a meticulously controllable micro-nanoscale amorphous hydroxide active layer, which serves as a cost-effective and highly efficient bifunctional electrocatalyst with remarkable catalytic activity and robust stability. We selected Fe(NO 3) 3 ·9H 2 O to induce the formation of amorphous Fe(OH) 3 layer with different thicknesse on the surface of NiSe/NF by adjusting the Fe3+ concentrations, thereby exposing additional active sites on the NiSe@FeOH/NF–C50 surface. Moreover, the incorporation of Se not only augments the chemical stability of NiSe but also significantly enhances the charge transfer efficiency between NiSe and Fe(OH)₃, while simultaneously improves interfacial stability. The synergistic effect between Ni and Fe significantly enhances the electron transfer rate, enabling the modified NiSe@FeOH/NF–C50 sample to exhibit outstanding OER/HER activity in 1 M KOH with current densities of 100 mA cm−2 at OER and HER overpotentials of 260 mV and 253.2 mV, and with low Tafel slopes of 56.9 mV·dec−1 and 85.7 mV·dec−1, respectively. When the NiSe@FeOH/NF–C50 is employed as a bifunctional catalyst for an alkaline electrolyzed electrode, requires a low cell voltage of 1.776 V to produce 50 mA cm−2 current density. Notably, the catalyst exhibits excellent stability over 60 h at 1.0 M KOH, underscoring its significant potential in commercial applications. • The bifunctional electrocatalyst NiSe@FeOH/NF–C50 is synthesized with a controllable nanoscale Fe(OH)₃ layer on NiSe/NF. • The electronic interactions between NiSe and Fe(OH)₃ optimize the electronic structure of NiSe. • The nanoscale Fe(OH)₃ layer lowers the overpotential for HER and OER of NiSe@FeOH/NF–C50. • NiSe@FeOH/NF–C50 showed outstanding stability during 60 h of electrolysis. [ABSTRACT FROM AUTHOR]

Zn‐air battery (ZAB)‐driven water splitting holds great promise as a next‐generation energy conversion technology, but its large overpotential, low activity, and poor stability for oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) remain obstacles. Here, a trifunctional graphene‐sandwiched, heterojunction‐embedded layered lattice (G‐SHELL) electrocatalyst offering a solution to these challenges are reported. Its hollow core‐layered shell morphology promotes ion transport to Co3S4 for OER and graphene‐sandwiched MoS2 for ORR/HER, while its heterojunction‐induced internal electric fields facilitate electron migration. The structural characteristics of G‐SHELL are thoroughly investigated using X‐ray absorption spectroscopy. Additionally, atomic‐resolution transmission electron microscopy (TEM) images align well with the DFT‐relaxed structures and simulated TEM images, further confirming its structure. It exhibits an approximately threefold smaller ORR charge transfer resistance than Pt/C, a lower OER overpotential and Tafel slope than RuO₂, and excellent HER overpotential and Tafel slope, while outlasting noble metals in terms of durability. Ex situ X‐ray photoelectron spectroscopy analysis under varying potentials by examining the peak shifts and ratios (Co2+/Co3+ and Mo4+/Mo6+) elucidates electrocatalytic reaction mechanisms. Furthermore, the ZAB with G‐SHELL outperforms Pt/C+RuO2 in terms of energy density (797 Wh kg−1) and peak power density (275.8 mW cm−2), realizing the ZAB‐driven water splitting. [ABSTRACT FROM AUTHOR]

Hydrogen energy with a high fuel value is considered to be one of the most important renewable and clean energy sources in sustainable energy. Electrocatalytic water splitting is the best way to produce hydrogen sustainably on a large scale. In this work, the sand rose‐like MoSe2/NiSe/NiFe layered double hydroxide (NiFe‐LDH) catalyst is obtained by a two‐step hydrothermal method for hydrogen evolution (HER) and oxygen evolution reaction (OER). The three‐dimensional (3D) hierarchical structure is observed by SEM, TEM, XRD and XPS, and the results showed that there is strong electronic interaction among the components, which promotes electron transfer and improves catalytic activity. In the alkaline environment, the catalyst exhibits excellent HER and OER performance, the current density of 10 mA cm−2 requires only 130 mV and 136 mV overpotential, respectively. In the water splitting system composed of MoSe2/NiSe/NiFe‐LDH as both cathode and anode, only 1.51 V voltage reaches the current density of 10 mA cm−2, and workes continuously for more than 120 h at 100 mA cm−2 current density with excellent stability. The Faraday efficiency of hydrogen production is close to 100 %. This study provides a promising strategy for the preparation of efficient electrocatalyst for overall water splitting. [ABSTRACT FROM AUTHOR]

Developing highly efficient and stable electrocatalysts in acidic media is essential for proton exchange membrane water electrolyzers (PEMWEs). Especially for oxygen evolution reaction (OER), high overpotential is needed to overcome the high thermodynamic energy barrier of water splitting. Herein, we report a high‐efficiency self‐supported ternary alloy OER catalyst with high activity and good durability in acidic electrolytes by a simple electrodeposition method. The as‐prepared electrocatalyst consists of Ru, Au, and Mn alloy which is deposited on the carbon fiber paper (denoted as RuAuMn‐CFP). The RuAuMn‐CFP exhibits superior activity and only requires an overpotential of 131 mV at 10 mA cm−2 and outstanding stability of 30 h (10 mA cm−2) in acidic media, which outperforms the commercial Ru/C and Ir/C catalysts. Besides, at an overpotential of 140 mV, the RuAuMn‐CFP catalyst exhibited a remarkable mass activity of 29.63 mA/mg for OER. It is 7.9 times and 23.8 times higher than the commercial Ru/C and Ir/C catalysts (3.73 mA/mg, 1.24 mA/mg, respectively). [ABSTRACT FROM AUTHOR]