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

Du, Jiaxin; Wu, Yunshuo; Fang, Siyu; Xu, Daliang; Liu, Min; Liang, Heng; Wu, Zhongbiao; Lu, Gaoqing Max et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

The electrochemical co-reduction of CO<sub>2</sub> 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<sup>-1</sup> g<sub>cat</sub><sup>-1</sup> at 250 mA cm<sup>-2</sup>, 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<sub>2</sub> 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.