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

The electrochemical co-reduction of CO 2 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 g cat –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–*NH 2 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 CO 2 –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.