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It is great significance to explore rich and efficient transition metal‐based electrocatalysts for the electrolysis of water. Nickel‐molybdenum (Ni−Mo) alloy is considering as one of the most promising electrocatalysts for hydrogen evolution reactions (HER) in alkaline electrolyte, but its catalytic performance for oxygen evolution reaction (OER) is still unsatisfactory. Heteroatom doping by interfering with the electronic structure of the catalysts has been considered to be an effective method to enhance electrocatalytic activities. Herein, we report the synthesis of iron (Fe)‐doped Ni4Mo intermetallic compound with hierarchical nanorod assemblies on nickel foam by hydrothermal and hydrogen‐induced methods, which significantly improve the catalytic performance for OER. The as‐prepared Fe−Ni4Mo/NF shows remarkable activity for alkaline oxygen evolution reaction, requiring only a low overpotential of 271 mV to achieve a current density of 100 mA cm−2. Such performance is significantly better than that of pristine Ni4Mo/NF with overpotential of 400 mV. Density functional theory (DFT) calculation shows that the addition of Fe can significantly reduce the adsorption energy of the intermediate on the catalyst surface, thus facilitating the OER activity. Moreover, an alkaline electrolyzer composed of Fe−Ni4Mo/NF as cathode and anode can provide 10 mA cm−2 current density with only 1.48 V extremely low voltage, and shows excellent long‐term durability of 24 h. These results highlight a heteroatom incorporation engineering strategy into metallic alloys for electrochemical applications. [ABSTRACT FROM AUTHOR]

Acidic water electrolysis is of great importance for boosting the development of renewable energy. However, it severely suffers from the trade-off between high activity and long lifespan for oxygen evolution catalysts on the anode side. This is because the sluggish kinetics of oxygen evolution reaction necessitates the application of a high overpotential to achieve considerable current, which inevitably drives the catalysts far away from their thermodynamic equilibrium states. Here we demonstrate a new oxygen evolution model catalyst-hierarchical palladium (Pd) whose performance even surpasses the benchmark Ir- and Ru-based materials. The Pd catalyst displays an ultralow overpotential (196 mV), excellent durability and mitigated degradation (66 μV h−1) at 10 mA cm−2 in 1 M HClO4. Tensile strain on Pd (111) facets weakens the binding of oxygen species on electrochemical etching-derived hierarchical Pd and thereby leads to two orders of magnitudes of enhancement of mass activity in comparison to the parent Pd bulk materials. Furthermore, the Pd catalyst displays the bifunctional catalytic properties for both oxygen and hydrogen evolutions and can deliver a current density of 2 A cm–2 at a low cell voltage of 1.771 V when fabricated into polymer electrolyte membrane electrolyser. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-supported titanium-doped nanosheet arrays (Ti-MnO 2 /CC) were obtained. • The obtained electrocatalysts exhibit excellent catalytic activities and stability. • Possible enhanced mechanism has been convinced. Efficient and sustainable hydrogen production via water electrolysis relies on the utilization of highly active electrocatalysts for the oxygen evolution reaction (OER). Birnessite (δ-MnO 2), a type of manganese oxide with a local atomic structure similar to the oxygen-evolving complex in photosystem II, has emerged as a highly promising OER catalyst. Despite considerable efforts have been dedicated to enhancing its activity, the crucial aspect of stability has been often overlooked. Herein, Ti ions have been selectively incorporated into the in-layered lattice of δ-MnO 2 nanosheet arrays using a hydrothermal method, aiming to enhance the stability without reducing its activity. The resulting optimal Ti-MnO 2 catalyst demonstrates enhanced OER activity in alkaline electrolyte, exhibiting an impressive 85 mV reduction in overpotential at 10 mA cm−2, surpassing the initial MnO 2 (495 mV reduced to 410 mV). Remarkably, it shows exceptional durability, with negligible performance decrease observed over the entire 50-hour testing period. It has been demonstrated that the incorporation of Ti serves a dual purpose: it adjusts the electronic structure around Mn, enhancing activity, and simultaneously stabilizes the Mn3+ active sites, resulting in exceptional durability. Furthermore, density functional theory (DFT) calculations provide additional confirmation of the optimized electronic structure of MnO 2 achieved through Ti doping, leading to a reduction in the free energy of adsorbed intermediates and expediting the kinetics of the OER process. Our findings open a pathway for enhancing OER stability and activity by doping electrocatalytic inert ions into the lattice of MnO 2 , applicable not only to Mn-based oxides but also other non-precious metal-based electrocatalysts. [ABSTRACT FROM AUTHOR]