Boosting Activity and Stability for the Alkaline Hydrogen Oxidation Reaction via Surface Reconstruction of Cu-Ni...

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.