Nano-confinement engineering boosts C–N coupling for urea electrosynthesis

The electrochemical co-reduction of CO2 and nitrate provides a sustainable route for urea synthesis via C–N coupling, yet kinetic limitations and poor intermediate interactions hinder urea yields. Here, we engineer a nano-confined CuRu bimetallic catalyst within mesoporous carbon hollow spheres (MCHS) to overcome these barriers. By spatially confining reactants and intermediates, the catalyst achieves a urea yield of 12.51 g h–1 gcat–1 at 250 mA cm–2, with 125-hour stability. In situ spectroscopy and computational analyses reveal that nano-confinement switches the C–N coupling pathway from the thermodynamically favored *COOH–*NH2 to kinetically driven *OCO–*NO intermediates, bypassing energy barriers. Precise pore-size engineering (4–11 nm) demonstrates that optimal confinement simultaneously enhances reactant transport and intermediate retention, boosting selectivity. This work establishes nano-confinement as a versatile approach for controlling multi-step electrocatalytic processes, enabling sustainable chemical synthesis. This study introduces a nano-confined CuRu catalyst that leverages confinement effects to enhance CO2–nitrate C–N coupling by improving reactant transport and strengthening the stabilization of key reaction intermediates, thereby achieving high urea yield and long-term operational stability.