Light‐Induced Electron‐Rich Gold Directs Nitrate Reduction to Dinitrogen

Electrocatalytic nitrate reduction reaction (NO 3 RR) provides a controllable route for nitrate conversion, while nitrate purification requires directing the reaction endpoint toward inert N 2 instead of soluble reactive nitrogen species. Here, we establish operating‐state electron enrichment as a design principle for directing NO 3 RR toward N 2 and construct a Cu‐induced electronically reconfigured Au (ER‐Au) interface that enters an electron‐rich state under illumination. Electrochemical in situ interfacial characterization and theoretical calculations show that this electron‐rich environment transforms *NO‐related intermediates from isolated adsorption states into N‐N coupling reactive configurations, selectively enabling the NO 3 − to N 2 branch. Consistent with this branch regulation mechanism, ER‐Au selectively converts NO 3 − to N 2 with 90.84% Faradaic efficiency at pH = 1, as confirmed by product analysis and isotope‐labeling experiments, and further maintains stable operation for 100 h under illuminated acidic NO 3 RR conditions. The high N 2 Faradaic efficiency shows competitive performance among representative NO 3 RR electrocatalysts reported in the literature, especially considering the challenge of directing nitrate reduction toward the inert N 2 endpoint. More broadly, these findings identify operating‐state electron enrichment as a key mechanism and design principle for endpoint‐selective NO 3 RR.