Stabilizing Water Dissociation Sites via Ethylenediamine Coordination for Industrial‐Current‐Density Alkaline Hydrogen Evolution Reaction

Abstract

ABSTRACT Incorporating water dissociation sites into electrocatalysts significantly boosts the catalytic activity for the alkaline hydrogen evolution reaction (HER), yet the reconfiguration of these sites under industrial‐level current densities—an issue that has received limited prior attention—severely impairs catalytic stability. Herein, we construct a highly active and ultra‐stable hybrid electrocatalyst composed of metallic nickel and a hydroxy(ethylenediamine)nickel(II) complex (Ni[(OH) 2 en x ]/Ni) via a scalable cathodic alkalization strategy. The interface‐coupled Ni[(OH) 2 en x ] complex, featuring high oxophilicity and enhanced thermodynamical stability against reduction, not only accelerates the water‐dissociation step but also renders long‐term catalytic durability. The resulting hybrid catalyst delivers a low overpotential of 35.2 mV at 10 mA cm −2 and a small Tafel slope of 43.68 mV dec −1 , outperforming the benchmark Ni(OH) 2 /Ni and Ni(OH) 2 /Pt catalysts. When integrated into an anion‐exchange membrane water electrolyzer, the electrode delivers 500 mA cm −2 for 3000 h in 1.0 M KOH at 25°C. This work demonstrates the great potential of coordination complexes as robust active sites for Volmer step, a concept that can be extended to other electrocatalytic reactions involving water dissociation.