Most transition metal‐based catalysts for electrocatalytic oxygen evolution reaction (OER) undergo surface reconstruction to generate real active sites favorable for high OER performance. Herein, how to use self‐reconstruction as an efficient strategy to develop novel and robust OER catalysts by designing pre‐catalysts with flexible components susceptible to OER conditions is proposed. The NiFe‐based layered double hydroxides (LDHs) intercalated with resoluble molybdate (MoO42−) anions in interlayers are constructed and then demonstrated to achieve complete electrochemical self‐reconstruction (ECSR) into active NiFe‐oxyhydroxides (NiFeOOH) beneficial to alkaline OER. Various ex situ and in situ techniques are used to capture structural evolution process including fast dissolution of MoO42− and deep reconstruction to NiFeOOH upon simultaneous hydroxyl invasion and electro‐oxidation. The obtained NiFeOOH exhibits an excellent OER performance with an overpotential of only 268 mV at 50 mA cm−1 and robust durability over 45 h, much superior to NiFe‐LDH and commercial IrO2 benchmark. This work suggests that the ECSR engineering in component‐flexible precursors is a promising strategy to develop highly active OER catalysts for energy conversion.

Pre‐catalyst reconstruction in electrochemical processes has recently attracted intensive attention with mechanistic potentials to uncover really active species and catalytic mechanisms and advance targeted catalyst designs. Here, nickel‐molybdenum oxysulfide is deliberately fabricated as pre‐catalyst to present a comprehensive study on reconstruction dynamics for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkali water electrolysis. Operando Raman spectroscopy together with X‐ray photoelectron spectroscopy and electron microscopy capture dynamic reconstruction including geometric, component and phase evolutions, revealing a chameleon‐like reconstruction self‐adaptive to OER and HER demands under oxidative and reductive conditions, respectively. The in situ generated active NiOOH and Ni species with ultrafine and porous textures exhibit superior OER and HER performance, respectively, and an electrolyzer with such two reconstructed electrodes demonstrates steady overall water splitting with an extraordinary 80% electricity‐to‐hydrogen (ETH) energy conversion efficiency. This work highlights dynamic reconstruction adaptability to electrochemical conditions and develops an automatic avenue toward the targeted design of advanced catalysts.

The key challenge of industrial water electrolysis is to design catalytic electrodes that can stabilize high current density with low power consumption (i.e., overpotential), while industrial harsh conditions make the balance between electrode activity and stability more difficult. Here we develop an efficient and durable electrode for water oxidation reaction (WOR), which yields a high current density of 10000 A m -2 at an overpotential of only 284 mV and shows robust stability even in 6 M KOH strong alkaline electrolyte with elevated temperature up to 80 °C. This electrode is fabricated from cheap nickel foam (NF) substrate through a simple one-step solution etching method, resulting in the growth of ultrafine phosphorus doped nickel-iron (oxy)hydroxide (P-NiFeOOH) nanoparticles embedded into abundant micropores on surface, featured as a self-stabilized catalyst-substrate fusion electrode. Such selfstabilizing effect fastens highly active P-NiFeOOH species on conductive NF substrate with significant contribution to catalyst fixation and charge transfer, realizing a winwin tactics for WOR activity and durability at high current densities in harsh environments. This work affords a cost-effective WOR electrode that can well work at large current densities, suggestive for rational design of catalyst electrodes toward industrial-scale water electrolysis.

Deep insight into electrochemical reconstruction aids in the decoding of electrocatalytic mechanisms and the development of design principles for advanced catalysts. Despite recent achievements, research concerning cathodic reconstruction is still lacking compared to the anodic variety. This work captures the electroreductive reconstruction dynamics over bimetal Ni–Mo sulfide by various in/ex situ techniques, and whereby cathodic reconstruction is steered with ion regulation to achieve a heterogeneous Ni–Mo–Fe ternary metal hydroxysulfide (NMFSOH) as a robust hydrogen‐evolving catalyst that is competent in industrial‐level water electrolysis. The thermodynamically adaptive heterosynergism in the resultant NMFSOH catalyst can coordinate water dissociation and hydrogenation for the alkaline hydrogen evolution reaction even at high current densities. A flow‐type alkaline water electrolyzer with dual NMFSOH electrodes affords an electricity consumption of 3.99 kW h Nm−3 and an electricity‐to‐hydrogen efficiency of 88.7%, manifesting its competitive cost‐effectiveness toward practical applications. This study showcases ion‐regulatory reconstruction as an effective strategy to construct high‐performance electrocatalysts.

The surface microstructure of a catalyst coating layer directly affects the active area, hydrophilicity and hydrophobicity, and the high porosity is desirable especially for solid–liquid–gas three-phase catalytic reactions. However, it remains challenging to customize catalyst distribution during the coating process. Here, we report a simple strategy for achieving ultrafine nanocatalyst deposition in a porous structure via introducing the surfactant into coating inks. For a proof-of-concept demonstration, we spin-coated the nanoscale IrO2 sol with a surfactant of sodium dodecyl sulfate (SDS) onto the glassy carbon (GC) electrode for oxygen evolution reaction (OER). Due to the surfactant action, the deposited IrO2 nanocatalyst is evenly distributed and interconnected into a highly porous overlayer, which facilitates electrolyte permeation, gas bubble elimination and active-site accessibility, thus affording high-performance OER in alkaline media. Particularly, the SDS-modified electrodes enable the industrial-level high-current-density performance via enhanced mass transfer kinetics. Such manipulation is effective to improve the coating electrodes’ catalytic activity and stability, and scalable for practical applications and suggestive for other gas-evolving electrodes.