Interfacial Ni³⁺ oxyhydroxide stabilization enables selective high-current-density ethanol oxidation in AEM electrolysis

Substituting the anodic oxygen evolution reaction (OER) with ethanol oxidation offers a promising route to lower the energy consumption of anion-exchange-membrane (AEM) electrolysis, but selective oxidation at industrially relevant current densities is often undermined by the emergence of OER-active states. Here, we identify stabilized Ni³⁺ oxyhydroxide as the key state that redirects anodic Ni chemistry away from oxygen evolution and toward selective ethanol oxidation under high-current operation. On a metallic Ni/defect-rich NiO heterointerface, anodic polarization triggers surface hydroxylation while retaining strong electronic coupling across the interface. Mechanistic studies combining operando Raman spectroscopy, post-reaction TEM/XPS, and density functional theory reveal that interfacial charge transfer facilitates early Ni²⁺/Ni³⁺ conversion, stabilizes Ni³⁺ oxyhydroxide species, decreases the OH⁎ deprotonation barrier, and inhibits overoxidation toward OER. This mechanism delivers 100 mA cm⁻² at only 120 mV and preserves selective, bubble-free ethanol oxidation up to 900 mA cm⁻². In an ethanol-hybrid AEM electrolyzer, the corresponding anode lowers the cell voltage by 370 mV at 1.0 A cm⁻² compared with conventional water electrolysis and sustains stable electrolysis for 200 h at 0.5 A cm⁻². Our results establish Ni³⁺ oxyhydroxide stabilization as a general design principle for high-rate selective anodic oxidation and energy-efficient hydrogen production.