Engineering Metallic Alloy Electrode for Robust and Active Water Electrocatalysis with Large Current Density Exceeding 2000 mA cm−2

Abstract The amelioration of brilliantly effective electrocatalysts working at high current density for the oxygen evolution reaction (OER) is imperative for cost‐efficient electrochemical hydrogen production. Yet, the kinetically sluggish and unstable catalysts remain elusive to large‐scale hydrogen (H 2 ) generation for industrial applications. Herein, a new strategy is demonstrated to significantly enhance the intrinsic activity of Ni 1‐x Fe x nanochain arrays through a trace proportion of heteroatom phosphorus doping that permits robust water splitting at an extremely large current density of 1000 and 2000 mA cm −2 for 760 h. The in situ formation of Ni 2 P and Ni 5 P 4 on Ni 1‐x Fe x nanochain arrays surface and hierarchical geometry of the electrode significantly promote the reaction kinetics and OER activity. The OER electrode provides exceptionally low overpotentials of 222 and 327 mV at current densities of 10 and 2000 mA cm −2 in alkaline media, dramatically lower than benchmark IrO 2 and is among the most active catalysts yet reported. Remarkably, the alkaline electrolyzer renders a low voltage of 1.75 V at a large current density of 1000 mA cm −2 , indicating outperformed overall water splitting. The electrochemical fingerprints demonstrate vital progress toward large‐scale H 2 production for industrial water electrolysis.