Hollow Fe‐Doped Ni(OH)₂–NiS@Ni(OH)₂ Nanorod Array with Regulated Heterostructural Interface and Band Structure for Expediting Alkaline Electrocatalytic Overall Water Splitting

Abstract Aiming to efficiently expedite alkaline overall water splitting (OWS) by addressing challenges such as sluggish kinetics and limited stability, a hollow Fe‐doped Ni(OH)₂‐NiS@Ni(OH)₂ nanorod array with surface nanosheets is devised, featuring a high‐index Fe‐doped Ni(OH)₂(101)‐NiS(211) heterostructural interface and an upshifted d‐band center. This nanoarchitecture intensifies the adsorption and interaction of H₂O and OH⁻ reactants on the electrocatalyst surface, suitably bonds the ^*H intermediate in hydrogen evolution reaction (HER) and accelerates electron movement of ^*H, minimizes the energy requirement of the rate‐limiting phase (^*OH → ^*O) in oxygen evolution reaction (OER) by facilitating O─H cleavage of ^*OH and optimally adsorbs ^*O, amplifies the exposure of surface‐active centers, and ultimately reduces the apparent activation energy. Consequently, the overpotentials are as low as 66.4 mV (HER) and 254.9 mV (OER) at 10 mA cm⁻², alongside high turnover frequencies of 142 s⁻¹ (H₂) and 279 s⁻¹ (O₂) at 100 and 300 mV, respectively, markedly outperforming direct‐electrodeposited analogues. When functioning as a bifunctional electrode in OWS, this material merely requires 1.57 V at 10 mA cm⁻² and sustains an operation for 168 h, approaching Pt/C||RuO₂ benchmark.