Sequential-chain coupling over hierarchical click-sites enables highly selective urea electrosynthesis

Electrochemical C - N coupling is an appealing approach for sustainable urea synthesis, while it is technically challenging due to the complex reaction mechanism and the spatiotemporal mismatch between C- and N- intermediates. Here, inspired by click chemistry, we design a hierarchical click-site catalyst (Se-InOx) that enables an efficient sequential-chain coupling pathway for urea electrosynthesis, achieving a urea yield rate of 254.94 mmol h-1 g-1, Faradaic efficiency of 78.61%, >85% Nurea-selectivity and 100% Curea-selectivity. Mechanistic studies reveal that Se-InOx as the first click-site can selectively adsorb NO3- and hydrogenate it to stable *NO2, while inhibiting CO2 adsorption at this stage. The surface-anchored *NO2 then acts as the second click-site to click couple with CO2, forming the key *CO2NO2 intermediate. This sequential-chain coupling strategy effectively resolves the spatiotemporal mismatch between N- and C- intermediates, thereby maximizing the suppression of side-reactions and enhancing C - N coupling selectivity. Techno-economic analysis and scalable synthesis validate the feasibility of this approach, providing a blueprint for high-selectivity multicomponent electrosynthesis.