Capturing Copper Single Atom in Proton Donor Stimulated O‐End Nitrate Reduction

Abstract Ammonia (NH 3 ) is vital in global production and energy cycles. Electrocatalytic nitrate reduction (e‐NO 3 RR) offers a promising route for nitrogen (N) conversion and NH 3 synthesis, yet it faces challenges like competing reactions and low catalyst activity. This study proposes a synergistic mechanism incorporating a proton donor to mediate O‐end e‐NO 3 RR, addressing these limitations. A novel method combining ultraviolet radiation reduction, confined synthesis, and microwave treatment was developed to create a model catalyst embedding Cu single atoms on La‐based nanoparticles ( p ‐CNCu s La n ‐m). DFT analysis emphasizes the critical role of La‐based clusters as proton donors in e‐NO 3 RR, while in situ characterization reveals an O‐end adsorption reduction mechanism. The catalyst achieves a remarkable Faraday efficiency (FE NH3 ) of 97.7%, producing 10.6 mol g metal −1 h −1 of NH 3 , surpassing most prior studies. In a flow cell, it demonstrated exceptional stability, with only a 9% decrease in current density after 111 hours and a NH 3 production rate of 1.57 mg NH3 /h/cm −2 . The proton donor mechanism's effectiveness highlights its potential for advancing electrocatalyst design. Beyond NH 3 production, the O‐end mechanism opens avenues for exploring molecular‐oriented coupling reactions in e‐NO 3 RR, paving the way for innovative electrochemical synthesis applications.