A Universal Approach for Sustainable Urea Synthesis via Intermediate Assembly at the Electrode/Electrolyte Interface

Electrocatalytic C-N coupling process is indeed a sustainable alternative for direct urea synthesis and co-upgrading of carbon dioxide and nitrate wastes. However, the main challenge lies in the unactivated C-N coupling process. Here, we proposed a strategy of intermediate assembly with alkali metal cations to activate C-N coupling at the electrode/electrolyte interface. Urea synthesis activity follows the trend of Li⁺ <Na⁺ <Cs⁺ <K⁺ . In the presence of K⁺ , a world-record performance was achieved with a urea yield rate of 212.8±10.6 mmol h^-1 g^-1 on a single-atom Co supported TiO₂ catalyst at -0.80 V versus reversible hydrogen electrode. Theoretical calculations and operando synchrotron-radiation Fourier transform infrared measurements revealed that the energy barriers of C-N coupling were significantly decreased via K⁺ mediated intermediate assembly. By applying this strategy to various catalysts, we demonstrate that intermediate assembly at the electrode/electrolyte interface is a universal approach to boost sustainable urea synthesis.