High-entropy composition design offers an effective approach to overcome the sluggish oxygen evolution reaction (OER) kinetics of lanthanum-based perovskite oxides. By incorporating a wider variety of metal cations into the B-site sublattice, the configurational entropy increases accordingly. Following this high-entropy compositional strategy, low-entropy LaCoO3, medium-entropy La(FeCoNi)O3, and high-entropy La(MnFeCoNiCu)O3 were successfully synthesized via a facile sol-gel combustion method. The construction of the high-entropy perovskite oxide (HEPO) was found to substantially alter the morphology, crystal structure, and electronic environment, leading to reduced particle size, modulated B-site metal valence states, and enriched oxygen vacancies. These modifications collectively induce synergistic effects among multiple B-site metal active sites and promote the participation of lattice oxygen through the introduction of surface oxygen defects, thereby activating the oxygen-mediated (LOM) pathway of OER. Remarkably, the as-prepared HEPO exhibited superior OER performance in alkaline media, achieving a low overpotential of 303 mV at 10 mA cm-2, a small Tafel slope of 43 mV dec-1, and excellent stability over 100 h of continuous operation. This work provides valuable insights into the role of B-site configurational entropy in perovskite oxides and highlights the potential of high-entropy design strategies for developing advanced OER electrocatalysts.

Rechargeable zinc-air batteries are promising candidates for grid-scale energy storage; however, their practical deployment is limited by oxygen electrocatalysis inefficiencies and interfacial instabilities, particularly outside conventional alkaline electrolytes. In this work, zinc-air batteries operating under neutral electrolyte conditions using ZnCl2 soaked KC-PAA-PAM gel polymer electrolytes and electrochemically synthesized Ni/Fe layered double hydroxide electrocatalysts is investigated. Ni/Fe-LDH is intentionally employed as an OER-biased benchmark catalyst to diagnose electrolyte and interface driven limitations rather than as a bifunctional ORR/OER solution. Full cells exhibit highly stable cycling over hundreds of hours, yet operate at substantially suppressed charge and discharge voltages relative to the thermodynamic value. Electrochemical impedance analysis shows that ohmic losses contribute only minimally to this voltage suppression. Post-mortem X-ray photoelectron spectroscopy reveals metallic zinc accumulation on the air cathode and chloride-containing species on the anode, indicating parasitic interfacial processes. Synchrotron-based soft X-ray absorption spectroscopy confirms stable Ni2+ and Fe3+ oxidation states during cycling, consistent with OER-biased catalytic behavior, while neutral-electrolyte oxygen evolution measurements demonstrate strong electrolyte-induced suppression of oxygen kinetics. Together, these results show that electrolyte chemistry and cathode-side parasitic processes, rather than catalyst identity alone, dominate voltage losses in neutral zinc-air batteries, providing mechanistic insight into the fundamental challenges associated with neutral electrolyte operation.

Designing a highly robust oxygen evolution reaction (OER) electrocatalyst under industrially relevant conditions, especially repeated start-up and shutdown cycling, is crucial to achieving efficient electrolysis when connected to a renewable energy source, such as wind and solar, for mass hydrogen production. This study investigates the degradation mechanisms of finely synthesized NiFe-, CoFe-, and CoNiFe-LDH via operando Raman and operando X-ray absorption spectroscopy and electrochemical analysis. The most active NiFe-LDH degraded severely under repeated on-off cycles versus constant OER operation due to a decrease in the conductivity of the catalyst, suppression of Ni oxidation, and amorphization. CoFe-LDH had the most degraded OER performance among the investigated catalysts under intermittent operation due to the large structural changes and significant Fe dissolution during cycling. In contrast, CoNiFe-LDH exhibited exceptional durability because of its high structural stability and redox robustness arising from its intermediate structural framework and modified electronic interaction with the coexistence of Co and Ni. Co helped Ni to oxidize more easily and contributed to maintaining its redox ability. The CoNiFe-LDH demonstrated noteworthy on-off durability under industrially relevant conditions (600 mA cm-2, 60 °C), indicating that CoNiFe-LDH is a promising OER electrocatalyst for durable alkaline electrolyzers.

The development of low-cost and high-performance noble-metal-free catalysts for the oxygen evolution reaction (OER) is central to advancing alkaline water electrolysis. This work introduces a novel "composition-thermal history" design strategy, synergistically combining controlled A-site Sr2+ doping with optimized high-temperature sintering (950°C) in Pr-based perovskite. The resulting Pr0.75Sr0.25Ni0.7Co0.3O3 (PSNC-25) exhibits unprecedented nanostructuring and a maximized concentration of oxygen vacancies, unlocking efficient OER via lattice oxygen-mediated mechanism. Sr-induced lattice distortion drastically reduces oxygen vacancy formation energy from 2.06 to 1.14eV, promoting facile lattice oxygen participation. Thermal engineering stabilizes high-valence Co4+/Ni3+ states and enhances M─O covalency. Electrochemically, PSNC-25 achieves exceptional activity in 1M KOH: a low overpotential of 389mV at 10mA cm-2 and a Tafel slope of 83mV dec-1, significantly surpassing undoped PrNi0.7Co0.3O3 (η10 ＞ 570 mV). It also exhibits robust durability, by > 120 h chronopotentiometry at 10mA cm-2 with only ∼45mV potential drift. This work establishes a rational framework for activating LOM in cost-effective perovskites through dopant-induced electronic modulation and nano-structural control, advancing scalable green hydrogen production.

The half reaction of oxygen evolution reaction (OER) has slow kinetics compared to the other reactions of hydrogen evolution reaction (HER) in electrocatalyst-based water splitting (WS) for hydrogen production. To improve the WS by an electrocatalyst, the use of spinel oxide based heterostructure (HS) catalysts supported by a carbon material is considered as a cost-effective strategy for the application of OER over noble metal catalysts. Here, for the first time, a novel WO3/NiCo2O4 heterostructure coupled with MWCNT was synergistically interface engineered via an ultrasonication-assisted hydrothermal synthesis method to achieve an efficient electrocatalyst based oxygen evolution reaction (OER) due to their significant electrochemical activity of HS. The rational integration of WO3 and redox-active NiCo2O4 with the highly conductive MWCNT framework results in a hierarchically porous heterointerface that promotes improved charge carrier transport, enhanced active site accessibility, and synergistic conductivity. The electrochemical results demonstrate the reduced overpotential of 323 mV at 10 mA cm-2 for MWCNT@WO3/NiCo2O4 with a Tafel slope of 123 mV dec-1, a reduced charge transfer resistance of 2.5 Ω, and a large electrochemical double-layer capacitance of 48.9 mF cm-2, outperforming its individual and WO3/NiCo2O4 counterparts. Improved reaction kinetics, reduced energy barriers, and superior electrochemical durability of over 38 h underscore the effectiveness of this interface engineering strategy. These findings highlight the promise of MWCNT@WO3/NiCo2O4 as a cost-effective, high-performance heterostructure for OER electrocatalysis in integrated water splitting and sustainable oxygen evolution reactions.

Abstract Designing acid‐stable RuO 2 catalysts capable of overcoming the activity‐stability trade‐off remains pivotal for advancing proton exchange membrane water electrolyzers (PEMWEs). Here, we introduce a cation‐vacancy engineering strategy to generate localized compressive strain in RuO 2 by electrochemically leaching Cd from a pre‐doped lattice. This strain modulation simultaneously elevates the Ru valence state (+4.35) and strengthens Ru─O covalent bonds, optimizing *OH/*O/*OOH adsorption energetics while suppressing over‐oxidation. The resulting V Cd ‐RuO 2 catalyst achieves an overpotential of 203 mV at 10 mA cm −2 in 0.1 M HClO 4 . Integrated into a PEMWE, it sustains >600 h operation at 200 mA cm −2 with a voltage degradation rate of 0.1 mV h −1 . The MEA based on V Cd ‐RuO 2 required cell voltages outperformed commercial RuO 2 by 120–180 mV at industrially relevant current densities (0.5–1.5 A cm −2 ), thereby demonstrating significant energy efficiency. Multiscale analyses confirm that compressive strain stabilizes high‐valence Ru sites through enhanced orbital overlap, reconciling catalytic activity with structural durability. This work establishes vacancy‐driven strain engineering as a universal approach for designing robust, Ir‐free OER electrocatalysts.

Designing acid-stable RuO2 catalysts capable of overcoming the activity-stability trade-off remains pivotal for advancing proton exchange membrane water electrolyzers (PEMWEs). Here, we introduce a cation-vacancy engineering strategy to generate localized compressive strain in RuO2 by electrochemically leaching Cd from a pre-doped lattice. This strain modulation simultaneously elevates the Ru valence state (+4.35) and strengthens Ru─O covalent bonds, optimizing *OH/*O/*OOH adsorption energetics while suppressing over-oxidation. The resulting VCd-RuO2 catalyst achieves an overpotential of 203mV at 10mA cm-2 in 0.1M HClO4. Integrated into a PEMWE, it sustains >600h operation at 200mA cm-2 with a voltage degradation rate of 0.1mV h-1. The MEA based on VCd-RuO2 required cell voltages outperformed commercial RuO2 by 120-180mV at industrially relevant current densities (0.5-1.5 A cm-2), thereby demonstrating significant energy efficiency. Multiscale analyses confirm that compressive strain stabilizes high-valence Ru sites through enhanced orbital overlap, reconciling catalytic activity with structural durability. This work establishes vacancy-driven strain engineering as a universal approach for designing robust, Ir-free OER electrocatalysts.

The development of efficient and durable nonprecious electrocatalysts for the oxygen evolution reaction (OER) is critical for sustainable hydrogen production. In this study, a defective CoFe-layered double hydroxide (LDH) support is engineered to stabilize isolated cerium atoms via a facile one-step coprecipitation approach. The resulting single-atom catalyst, denoted Ce0.2CoFe-LDH, is thoroughly characterized by atomic-resolution electron microscopy and synchrotron-based X-ray spectroscopy, which confirm the atomic dispersion of Ce3+ species anchored at cation vacancy sites within the LDH matrix. A strong electronic interaction between Ce and Co/Fe sites is observed, leading to charge redistribution that increases the valence states of transition metals and activates dynamic Ce3+/Ce4+ redox cycling. The optimized catalyst exhibits outstanding OER performance in alkaline media, achieving an overpotential as low as 227 mV at 10 mA·cm-2, a Tafel slope of 48.3 mV·dec-1, and excellent stability over 50 h of continuous operation. Electrochemical measurements indicate facilitated charge transfer and an increased electrochemically active surface area. First-principles calculations further reveal that Ce atoms occupying Co vacancies significantly optimize the adsorption of reaction intermediates, reduce the energy barrier of the rate-determining step to 1.81 eV, and induce metallic character through an upshift of the d-band center. This work establishes defect-driven single-atom anchoring as an effective strategy for electronic structure modulation and reaction pathway optimization in LDH-based electrocatalysts, offering valuable insights for the design of high-performance energy conversion materials.

Diabetic wound healing is substantially impaired by biofilm infections, oxidative stress, and persistent hypoxia, which present major challenges for timely diagnosis and treatment. In this study, theranostic nanoparticles (NPs) were engineered to facilitate lipase-triggered biofilm theranostics and accelerate wound healing. Theranostic Mn-TC NPs were prepared by grafting a fluorescent sonosensitizer, meso-tetra (4-carboxyphenyl) porphine (TCPP), onto manganese dioxide (MnO2) nanoflowers, quenching the fluorescence emissions of TCPP. Upon encountering biofilms in vivo, the elevated lipase hydrolyzes ester linkages within the Mn-TC NPs, liberating TCPP to restore its fluorescence emission and enabling the real-time visualization of biofilm-infected wounds. MnO2 nanoflowers offer abundant reaction sites for TCPP grafting while enhancing the catalysis of hydrogen peroxide to generate oxygen. The boosted oxygen evolution promoted the sonodynamic therapy effect of ultrasound-activated TCPP, achieving 94.0% reduction in biofilm biomass and 99.9% bacterial clearance. Engineering NPs accelerate wound healing by simultaneously eradicating biofilms, modulating inflammatory states, enhancing collagen deposition, and promoting angiogenesis. This study presents a novel theranostic strategy for biofilm-triggered visual imaging and an antibiotic-free therapy for diabetic wounds.

Recent studies on the electrocatalytic oxygen transfer from water to organic compounds have gained significant attention due to their sustainability and selectivity. However, the direct coactivation of inert hydrocarbons and water typically requires high oxidation potentials, leading to oxygen evolution reactions and low Faradaic efficiencies. Herein, a Ni-activated tungsten-oxygen covalency anode is designed for the efficient oxygen transfer from water to benzylic C(sp3)-H bonds via a Ni-regulated interfacial water structure between the anode and electrolyte. Both experimental and theoretical results reveal the critical role of W-O covalency sites with Ni-heteroatoms for boosting efficient oxygen transfer via breaking the dense interfacial hydrogen bond network and inhibiting the undesired oxygen evolution reactions, facilitating the coactivation of oxygen species and C(sp3)-H bonds. Thus, a Faradaic efficiency of > 56% in a water-involved system has been achieved. This work provides important insight into designing electrocatalytic systems for inert C-H oxidation.

Spillover phenomenon, which is characterized by the dynamic migration of active species across catalyst surfaces, provides a promising avenue to overcome the limitations dictated by the Sabatier principle in conventional catalysis. This comprehensive review highlights recent progress in multiplicate spillover, including hydrogen, oxygen, hydroxyl, and intermediate spillover, and their critical roles in modulating intermediate adsorption, strengthening interfacial transport, and manipulating catalytic dynamics. Then, various spillover-mediated electrocatalytic reactions, such as hydrogen and oxygen evolution, carbon dioxide and nitrogen reduction, and methanol oxidization reactions, are systematically summarized. Finally, current challenges of different spillover systems are critically assessed and future research directions are briefly outlined. It is expected that this review offers some useful guidance on rational design of high-performance spillover-based electrocatalysts and promote advancement of sustainable energy conversion technologies.

Transitional metals (TMs)-based high-entropy alloys (HEAs) have demonstrated exceptional oxygen evolution reaction (OER) activity due to tunable electronic configurations and multimetallic synergy. However, their stability is hindered by oxidation and structural degradation resulting from intermetallic electron interactions during operation. Herein, we propose a cerium-mediated charge redistribution strategy in FeCoNiMnCe HEA, facilitating charge transfer from electron-rich Ce to neighboring TMs. This Ce-introduced HEA features increased dissolving activation energy of Fe/Mn and optimized electronic orbitals of Co/Ni, which inhibits the deactivation of active sites induced by high oxidized states during OER. Benefiting from charge accumulation on TMs, FeCoNiMnCe HEA achieves outstanding durability with negligible decay over 1000 h for OER at 10 mA cm-2 and enables stable zinc-air batteries operation for 4600 h at 2 mA cm-2. This work provides a robust strategy for designing stable HEA electrocatalysts through targeted electronic modulation.

In the pursuit of a technological breakthrough in zinc-air batteries, it is critical to find economical, durable, and high-performance catalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) to accelerate the slow reaction kinetics. Herein, a one-pot method was employed to synthesize the polymer within a mixed solvent of CHCl3 and CH3OH (v/v = 2:1). The resulting polymer can be well-dispersed in deionized water to form an aqueous metal-organic gel (MOG). Testing has revealed that Co-MOG exhibits dual catalytic properties for both the OER and ORR, a characteristic that is notably rare in original MOG materials. Furthermore, it demonstrates exceptional long-term charge-discharge cycling stability in zinc-air batteries, outperforming several reported Co-based catalysts for the OER and ORR. X-ray absorption spectroscopy and density-functional theory (DFT) calculations indicate that the CoN3 configuration serves as the catalytically active site of the material. In conclusion, this work supports the application of MOGs as unique bifunctional electrocatalysts for the OER and ORR in metal-air batteries.

The rational design and synthesis of efficient and durable bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of great significance and challenging for rechargeable zinc–air batteries. While much attention has been devoted to enhancing ORR performance in recent studies, the effectiveness of OER is equally crucial for charging performance of Zn–air batteries. In this work, NH2-MIL-101(Fe) is employed as a precursor to derive Fe-NC through a straightforward pyrolysis method. Subsequently, NiFe-LDH is synthesized on the surface of Fe-NC via a wet-chemical process to obtain Fe-NC@NiFe-LDH. Capitalizing on the synergistic interplay between Fe-NC, serving as the ORR active site, and NiFe-LDH, acting as the OER active site, Fe-NC@NiFe-LDH demonstrates remarkable bifunctional electrocatalytic performance, boasting a positive half-wave potential of 0.83 V for ORR and a low potential of 1.68 V for OER at a current density of 10 mA cm−2, alongside exceptional stability in alkaline environments. Furthermore, the Fe-NC@NiFe-LDH-based Zn–air battery exhibits outstanding discharge and charge performance, maintaining excellent cycling stability over 600 h (3600 cycles).

The lower thermodynamic potential of the urea oxidation reaction (UOR) makes it an ideal alternative to the conventional oxygen evolution reaction (OER). However, most Ni-based UOR catalysts face intrinsic limitations due to the high oxidation potential of Ni3+, coupled with insufficient selectivity. Herein, F/Mo codoped Ni-based catalyst F-MoNiP is obtained with an amorphous nanotube structure. The F/Mo codoped strategy enhances UOR activity by facilitating the formation of catalytically active NiOOH species at low overpotential and simultaneously promotes urea decomposition through the environmentally preferred carbonate pathway. Moreover, the presence of F effectively suppresses the OH- adsorption, thereby minimizing the competition with OER. This synergistic optimization enables F-MoNiP to achieve exceptional catalytic performance, operating at a cell voltage of 1.395 V to deliver a current density of 10 mA cm-2 in urea-assisted electrolysis of water. These findings offer a sustainable and energy-efficient route for hydrogen production through urea electrolysis.

Electrochemical water splitting for hydrogen production is limited by the slow kinetics of the oxygen evolution reaction (OER). The tunable structure and anion-exchange capability of layered double hydroxides (LDHs) underpin their promise as OER catalysts. Consequently, the strategic incorporation of foreign anions is viewed as a powerful approach to engineer their active sites and boost catalytic activity. This review summarizes how doping with anions such as NO3−, PO43−, Cl−, F−, and Sq2− modifies the electronic structure of LDHs. These anions regulate the local coordination environment, induce oxygen vacancies, and alter metal oxidation states, thereby synergistically optimizing both the adsorption–evolution mechanism (AEM) and the lattice oxygen oxidation mechanism (LOM). For instance, NO3− promotes surface reconstruction, F− activates lattice oxygen, PO43− stabilizes the interface, Cl− reshapes reaction pathways, and Sq2− maintains interfacial alkalinity. Collectively, rational anion engineering lowers the overpotential, increases current density, and improves stability, establishing an effective design framework for advanced LDH-based OER electrocatalysts.

The morphology and crystalline structure of semiconductor materials both play important roles in determining the photocatalytic activity of such materials. In this regard, tantalum nitride (Ta3N5) shows promise as a visible-light-responsive photocatalyst for solar-driven water splitting. Even so, the performance of this material is limited by its bulk morphology and by high defect densities and inefficient charge transport. The present work synthesized single-crystalline Ta3N5 nanosheets having reduced defect concentrations and an increased specific surface area via the direct nitridation of two-dimensional TaS2 nanosheets. The Ta3N5 nanosheets had a thickness of approximately 30 nm with well-defined exposed facets and a uniform single-crystalline structure, and so led to a shorter charge-carrier diffusion length along with efficient charge separation and transport. When modified with IrOx as a cocatalyst, these nanosheets provided an apparent quantum yield of 32.4% at 420 nm during photocatalytic oxygen evolution with sacrificial electron acceptors, outperforming Ta3N5 synthesized from Ta2O5. This material was also integrated into Z-scheme photocatalyst sheets together with La5Ti2Cu0.9Ag0.1O7S5 as the hydrogen evolution photocatalyst and carbon nanotubes as the electron mediator. These sheets enabled overall water splitting with stoichiometric H2 and O2 evolution in response to visible light, with a light absorption range extended to approximately 600 nm. This work underscores the critical roles of precursor selection and nanoscale morphological control in the development of photocatalysts with minimal defects and provides new insights expected to advance the field of solar-to-chemical energy conversion.

Enhancing the oxygen evolution capacity of materials constitutes a pivotal strategy for augmenting electrochemical catalytic efficacy. Here we report enhanced oxygen evolution reaction (OER) activity in Sr2Ir1-xFexO4. The incorporation of Fe modifies the electronic structure of Ir and stabilizes its high oxidation state, facilitating the stabilization of reaction intermediates and accelerating the kinetics of the OER. Specifically, Sr2Ir0.91Fe0.09O4 requires only 264 mV to reach 10 mA cm-2 in 1 M KOH, exhibits a Tafel slope of as low as 52.9 mV dec-1, and delivers a 1.9-fold increase in electrochemically active surface area (ECSA). The catalytic activity of Sr2Ir1-xFexO4 samples is enhanced through electronic structure alteration of substituting elements, increasing the active site reactivity and oxygen evolution capability. This study provides insights into the design of an OER catalyst through 3d and 5d metal synergies, advancing electrocatalyst development.

Synergistic effects of axial ligands on the oxygen evolution and oxygen reduction reactions catalytic performance of Cu-N-C single-atom catalysts: A density functional theory study

Mitigating electronic limitations in Co3O4 via rational dopant integration for multifunctional sustainable energy applications: Oxygen evolution and photoelectrochemical water reduction