Tailoring deep reconstruction of phosphide to oxyhydroxide via dual heteroatom modification for efficient oxygen evolution catalysis

Deep reconstruction of metal phosphides facilitates formation of abundant active oxyhydroxides, thereby accelerating oxygen evolution reaction (OER). However, rapidly achieving such reconstruction under low overpotentials remains challenging due to energy inefficiency and catalyst delamination risks. Herein, Fe/V co-doped nickel phosphide (FVNP) is designed to promote deep reconstruction into active oxyhydroxide (FVNOOH). Operando experiments reveal that Fe lowers reconstruction onset potential while V accelerates kinetics. Theoretical calculations demonstrate that Fe/V co-incorporation optimizes key steps (*OH→*O and O*→OOH*), upshifts d-band center of FVNOOH, and reduces OER barrier. The resulting FVNOOH exhibits a low overpotential of 226.1 mV at 100 mA cm⁻² and high mass activity of 27.9 A mg⁻¹ at −0.05 V vs. RHE. Impressively, an FVNOOH-based electrolyzer requires only 1.50 V to reach 10 mA cm⁻² and operates stably for 300 h at 50 mA cm⁻². Moreover, a decoupled water electrolysis (DWE) system using FVNOOH for stepwise H₂ and O₂ production attains a cell voltage of 1.69 V at 10 mA cm⁻² and sustains over 50 consecutive cycles, outperforming most DWE systems (including noble metal-based counterparts). This work offers a rational strategy for deep reconstruction control and provides fundamental insights into enhanced OER catalysis.