Co-reduction coupling of bicarbonate and nitrate toward efficient urea synthesis.

The electrocatalytic reduction of carbon dioxide (CO) and different nitrogenous substances has shown a broad prospect in replacing the traditional urea synthesis process, but there are still serious challenges in mass transfer at the gas-liquid-solid interface. The conversion of bicarbonate (HCO) and nitrate (NO) into urea the C-N coupling process under environmental conditions is a promising alternative to traditional industrial urea synthesis, which uses CO as the carbon source. However, initiating the C-N coupling reaction through the adsorption and activation of HCO and NO is considerably challenging. Designing and engineering highly selective and active electrocatalysts are necessary to accelerate electrochemical urea synthesis. Herein, we constructed a Mott-Schottky heterogeneous catalyst by loading Cu nanoparticles onto WN nanosheets (Cu-WN), achieving an excellent faradaic efficiency (FE) of 15.9% and urea yield rate of 421 μg h mg at -0.3 V RHE, outperforming the majority of reported electrocatalysts. Results show that the spatial charge region induced by the Mott-Schottky heterostructure facilitates the simultaneous adsorption and activation of HCO and NO, accelerating the multiple-electron transfer process. This work furnishes a promising impetus for the advancement of urea electrosynthesis electrochemical C-N coupling under ambient conditions.