Crystalline Fe‐Doped Ni 2 B Catalyst: Molten Salt‐Assisted Electrochemical Synthesis for Enhanced Oxygen Evolution Reaction

Abstract Transition‐metal borides offer unique advantages as catalysts for oxygen evolution reactions (OERs). However, current research on borides has primarily focused on amorphous powders, and there is no unified understanding of the precise role of B and its catalytically active centers. In this study, we propose the synthesis of a crystalline Fe‐doped Ni 2 B catalyst using a molten salt‐assisted electrochemical etching method to oxidize an Fe 2 AlB 2 precursor. The catalyst exhibited excellent catalytic activity in 1 M KOH, with an overpotential of only 245 mV at 10 mA cm −2 . This activity can be attributed to boride dissolution, which promoted the surface conversion of Fe‐doped Ni 2 B to (Ni,Fe)OOH x during the OER. Further experiments and density functional theory calculations revealed that the synergistic effect between the inner layer of Fe‐doped Ni 2 B and the outer layer of (Ni,Fe)OOH x was essential for improving electrocatalytic performance. This study provides a new approach for designing highly efficient boride OER catalysts.