Monitoring Activation Intermediates via Operando Target-Specific NMR Enables Selective C–N Coupling for Urea Electrosynthesis

Electrocatalytic urea synthesis from CO₂ and NO₃^– offers a sustainable nitrogen–carbon route but faces challenges from complex electron transfer and side reactions. Here, we design a SnO₂/CuO_x heterojunction catalyst with an optimized Sn:Cu ratio of 1:5.5, denoted as m-SnO₂/CuO_x, to promote C–N coupling by balancing *CO and *NH₂OH adsorption. The m-SnO₂/CuO_x interface enables selective N-terminal hydrogenation of *NO to *NH₂OH while suppressing the hydrogen evolution reaction and NH₃ formation. In situ infrared spectroscopy reveals the site-specific activation of CO₂ on SnO₂ and NO₃^– on CuO_x. Operando ¹H, ¹³C, ¹⁵N, and ¹⁷O NMR confirms that *NH₂OH couples with *CO via the *H₂NCHO intermediate to form urea. Density functional theory calculations indicate that interfacial charge redistribution lowers energy barriers and stabilizes intermediates. The optimized catalyst delivers a urea yield of 215 mmol g^–1 h^–1 and a Faradaic efficiency of 72.18%. This study underscores the role of rational catalyst design, together with operando insights, in advancing efficient electrocatalytic urea production.