Synergistic Enhancement of Electrocatalytic Water Splitting Via Fe‐Doping and Heterointerface Engineering in Fe‐Ni _0.85 Se/Ni(OH) ₂ Nanosheet Arrays

ABSTRACT Efficient, stable, non‐noble metal bifunctional electrocatalysts are essential for scalable water electrolysis. In this work, a two‑step hydrothermal method was used to construct self‐supported Fe‐doped Ni 0.85 Se/Ni(OH) 2 /NF three‐dimensional porous nanosheet arrays on nickel foam. Systematic characterizations confirm that Fe doping effectively modulates the electronic structures of Ni and Se, while the heterointerface formed between Ni 0.85 Se and Ni(OH) 2 further optimizes the surface properties of the material. In 1 M KOH electrolyte, the catalyst demonstrates outstanding electrocatalytic performance, requiring overpotentials of only 213 mV for OER and 95 mV for HER to achieve current densities of 10 mA cm −2 . When assembled as both the anode and cathode in a full water‑splitting electrolyzer, a cell voltage of only 1.55 V is needed to drive a current density of 10 mA cm −2 . Moreover, the system exhibits negligible performance decay over 100 h of continuous operation. This work demonstrates a feasible strategy for designing high‐performance, self‐supported bifunctional catalysts via dual modulation of doping and interface engineering.