CeOx-Integrated dual site enhanced urea electrosynthesis from nitrate and carbon dioxide.

Abstract

Electrocatalytic urea synthesis via the co-reduction of NO 3 - and CO2 as a promising option to the conventional Bosch-Meiser remains challenged by regulating desired intermediates to simultaneously achieve a high yield and Faradaic efficiency. Here, we integrate the substrate material (SiO2) and functionally atomic sites (Cu and Sn) utilizing CeOx nanoclusters as 'adhesive', in which the CeOx and SiO2 form the composite carrier (CS) construct Cu and Sn diatomic electrocatalyst (CuSn/CS-1). Spectroscopic techniques and density functional theory calculations reveal that overall charge redistribution in the CeOx-CuSn modules forms bifunctional active sites with unique electronic properties and abundant oxygen vacancies. The Cu sites mediate the conversion of CO2 to *CO through a single carbon-coordinated structure with *CO2-, while Sn sites regulate the reduction of NO 3 - to stabilize the formation of *NH2, broadening the C-N coupling route. Oxygen vacancies provide additional electron storage sites and promote the electron flow during the electrocatalytic process. CuSn/CS-1 achieves a urea yield of 55.81 mmol g-1cat. h-1 with a Faradaic efficiency of 79.27% in H-cell at -0.7 V versus the reversible hydrogen electrode. This work overcomes the traditional trade-off between urea yield and Faradaic efficiency, providing a feasible and sustainable strategy.