ABSTRACT Electrochemical reduction of nitrate to nitrogen (N 2 ) offers a sustainable pathway to close the nitrogen cycle and mitigate nitrate pollution. However, for Cu, Co, and other transition‐metal catalysts, high N 2 selectivity has mainly relied on breakpoint chlorination, which consumes large amounts of chlorine and poses secondary contamination risks. Here, we introduce a surface‐oxophilicity strategy to steer the * N pathway, thereby enhancing both catalytic efficiency and intrinsic nitrogen selectivity. Among oxophilicity‐modified Pd, Sn doping emerged as the optimal configuration. The resulting PdSn metallene aerogels achieve remarkable NO 3 − ‐N conversion (∼97%) and N 2 selectivity (∼99%), together with long‐term stability (>600 h) and broad tolerance to variable nitrate concentrations. In situ characterization and theoretical analyses reveal that Sn‐induced oxophilicity strengthens nitrogen‐oxygen intermediate adsorption, ensuring sufficient * N availability for N‐N coupling while elevating the hydrogenation barrier of * N → * NH, thus suppressing NH 3 formation. Integrated into a Zn‐NO 3 − battery and a customized gas‐integrated flow electrolyzer, the catalyst enables efficient nitrate removal and nearly complete N 2 selectivity, offering a promising platform for sustainable nitrogen recycling and energy conversion.
Wang et al. (2026) studied this question.