Asymmetric bridge adsorption at a Cu2O/CoO heterointerface enables efficient electrocatalytic nitrate reduction to ammonia

Cu-Co nanoalloys were constructed and employed to drive electrocatalytic nitrate reduction to ammonia (ENRA). Comprehensive structure and electrochemical characterizations combined with theoretical calculations decipher that Co incorporation elevates the d -band center and keeps moderate aqueous *H supply, facilitating adsorption and hydrogenation of nitrate and oxynitride intermediates. Crucially, an efficiently integrated Cu 2 O/CoO heterojunction emerged on the surface of the Cu-Co nanoalloy. Spontaneous local charge redistribution at the Cu 2 O/CoO interface gives rise to distinct nucleophilic and electrophilic regions. Such heterogeneous structure is favourable for targeted asymmetric bridge adsorption of oxynitrides (*NO 2 , *NO), thus promoting breakage of N-O bond and suppressing the accumulation and desorption of intermediates. As a result, CuCo 3 exhibits excellent ENRA performance, featured with a nitrate removal rate of 74.7%, an ammonia selectivity of 98.7%, and a Faradaic efficiency of 90.2% at −0.6 V vs. RHE under neutral electrolyte. Coupling ENRA with an air stripping process, high purity solid NH 4 Cl is successfully obtained with a nitrogen recovery rate of 80% in conjunction with a high energy efficiency of 73%, demonstrating the practical feasibility of converting nitrate-containing wastewater into value-added ammonia products.