Boosting Activity and Stability for the Alkaline Hydrogen Oxidation Reaction via Surface Reconstruction of Cu‐Ni Core–Shell Electrocatalysts Through Oxygen Intercalation

ABSTRACT The development of efficient and durable platinum group metal (PGM)‐free electrocatalysts for the alkaline hydrogen oxidation reaction (HOR) is critical but remains challenging due to unfavorable hydrogen binding energy (HBE) and hydroxyl binding energy (OHBE) of nickel‐based electrocatalysts. Nickel‐based catalysts also experience rapid degradation under operating conditions. Herein, we report a surface reconstruction strategy to simultaneously tailor the HBE and OHBE of Cu‐Ni core–shell electrocatalysts via nitric acid etching. This process removes the Ni‐rich surface layer and induces oxygen intercalation into the top ∼10 atomic layers, accompanied by Cu redistribution near the surface. The resulting oxygen‐intercalated surface protects Ni from anodic oxidation, while Cu incorporation stabilizes the bimetallic structure, addressing the stability challenge. The as‐prepared electrocatalyst (Cu@O _i ‐NiCu) exhibits a downshifted Ni d ‐band center that optimizes HBE, while intercalated oxygen modulates orbital alignment and anti‐bonding filling to strengthen OHBE. As a result, Cu@O _i ‐NiCu achieved a current density of 2.33 mA cm ⁻² at an overpotential of 100 mV, and demonstrated a kinetic current density of 5.26 mA cm ⁻² . Moreover, it maintained 93.5% activity after 10 000 cycles. This work offers a controllable surface‐reconstruction route for modulating hydrogen and hydroxyl binding and provides a generalizable strategy for constructing stable HOR catalysts.