Cu‐Doped Activated Co ₃ O ₄ : Tandem Site Efficient Electrocatalytic Reduction of Nitrate to Ammonia

Abstract The electroreduction of nitrate (NO 3 − ) into ammonia (NH 3 ) presents a promising avenue for sustainable ammonia synthesis. In this study, we construct electrocatalyst with tandem sites that integrates highly dispersed Cu with Co 3 O 4 by self‐sacrifice strategy using MOF as a template, which significantly improves NH 3 production. The resulting Cu–Co 3 O 4 catalyst achieves an NH 3 yield rate of 7.25 mg h −1 cm −2 and Faradaic efficiency (FE) of 95%. Mechanism research shows that Cu enhances NO 3 − adsorption, the synergy between Cu and Co 3 O 4 increases the electrochemical active area, reduces charge transfer resistance, and inhibits hydrogen evolution reaction. The confinement effect of Co 3 O 4 effectively ensures the stability of Cu 2+ in the electrocatalytic reduction reaction process. This work offers valuable insights into the tandem NO 3 − reduction pathway in heterostructures, providing a foundation for optimizing catalysts and advancing sustainable NH 3 synthesis.