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NiFe oxyhydroxides, generally reconstructed on surface during oxygen evolution reaction (OER), are real active species for water oxidation; however, their direct and convenient preparation remains challenging. Here, we develop a one-step approach to prepare biphase (α/δ) Ni-doped FeOOH catalyst in 3 min under room temperature. The core of this ultrafast method is that Fe2+ derived from the redox reaction of Fe3+ and Ni2+ accelerate Fenton-like reaction, while simultaneously producing mixed-valence Ni ions(Ni2+, Ni3+) results in not only homovalent and heterovalent doping, but also biphase Ni-doped FeOOH heterojunction with high and low crystallinity. Specifically, Ni2+ doping leads to a preferred formation of low-crystalline δ-oriented Ni-doped FeOOH with abundant oxygen vacancies, which is in favor of triggering the lattice oxygen mechanism (LOM) during OER. Benefitting from high/low crystalline biphase heterojunction and LOM, the optimized Ni-FeOOH merely needs low overpotential of 300 mV to reach 1000 mA cm−2 for OER in alkaline electrolyte and also shows excellent durability even at a high current density of 500 mA cm−2. This work provides a cost-effective strategy to fabricate highly active and robust non-noble electrocatalysts that can potentially be applied for industrial-scale OER electrolysis. [ABSTRACT FROM AUTHOR]

FeNiOOH is regarded as the most stable active species in the oxygen evolution reaction (OER), but the high oxidation energy of NiOOH poses a challenge to directly synthesize FeNiOOH as a real OER catalyst. Herein, an anion‐mediated kinetically controlled strategy is proposed, coupled with cation‐induced geometric topology modulation, to directly synthesis FeNiOOH with ultra‐thin, densely packed nanosheet architectures. Specifically, the Cl−‐mediated in situ generation of hypochlorous acid promotes the direct formation of NiFeOOH. Concurrently, high‐valence competitive Ru3+ mitigate electrostatic repulsion, fostering a compact and densely packed assembly of Ru/FeNiOOH nanosheet branches. Furthermore, the intrinsic electron‐capturing ability of FeOOH, in synergy with the stabilizing effect of doped Ru atoms, further promote the formation and stabilization high‐valence NiOOH. Consequently, the hierarchical Ru/FeNiOOH@NiPOx nanoarray catalyst displays exceptional OER performance, with an overpotential of 172 mV at 10 mA cm−2 and outstanding stability. This study provides a novel strategy to directly construct a real catalyst. [ABSTRACT FROM AUTHOR]