Driving Adsorbate Evolution via Oxygenated Surface Species Modulation for Ammonia Electrooxidation

Abstract The electrochemical ammonia oxidation reaction (eAOR) to dinitrogen offers a promising pathway for sustainable nitrogen cycles and hydrogen generation. However, despite mechanistic insights into *NH x dehydrogenation and OH − ‐mediated proton‐coupled electron transfer, conventional metal catalysts, including Pt and Pt‐Ir alloys, still suffer from sluggish kinetics and poor stability. Here, we report that controlling oxygenated co‐adsorbates steers the adsorbate‐evolution pathway of the eAOR to N 2 . An exsolved Pt 3 Ni alloy on a perovskite scaffold selectively stabilizes *OOH and strengthens *NH 2 binding via interfacial charge redistribution (elevated surface potential) and a raised Pt d ‐band center. In situ Fourier transform infrared spectroscopy combined with density functional theory reveals that both the *NH x ‐to‐*N dehydrogenation and *OOH formation steps critically affect the rate‐determining process via the N 2 H 4 pathway of the Gerischer–Maurer (G–M) mechanism. Benefiting from (oxy)hydroxide‐assisted eAOR, the catalyst delivers mass activity up to 862 A g Pt −1 , surpassing the state‐of‐the‐art benchmarks. When deployed in a solar‐driven ammonia electrolyzer, the catalyst achieves 13.7 mA at cell voltage of 1.0 V, and stable solar‐driven hydrogen production at 394 L kWh −1 (NH 3 removal rate of 62 mg/day) in landfill leachate‐like wastewater conditions. These findings establish an absorbate‐assisted mechanism design approach for developing advanced N‐species electrocatalysis.