Charge Polarization Boosting Electrochemical Urea Synthesis by Co‐Reduction of CO2 and Nitrite in Dilute Concentrations with a Unity Carbon Selectivity

Abstract

Synthesis of urea through electrocatalytic coupling reaction of CO2 with nitrite (NO2‐) represents a sustainable means to substitute the conventional energy‐intensive urea synthetic protocol. The direct conversion of dilute NO2‐ in real wastewaters to urea with high efficiency is still a significant challenge, as C‐intermediates tend to go through an extensive reduction achieving mostly C‐containing productions due to the lack of N‐intermediates, originating from slow diffusion rate of NO2‐. Herein, we report the charge‐polarized Feδ‐‐Cuδ+ dual sites in metal/carbon heterojunction material (Cu@Fe‐N‐C) for co‐reduction of CO2 and dilute NO2‐ solution (100 ppm NO2‐‐N). The electron‐rich single Fe atoms dispersed N‐doped carbon (Fe‐N‐C) restrain *CO desorption, and the electron‐deficient Cu nanoparticles (Cu) promote the deep reduction of NO2– to *NH2. As a result, the obtained Cu@Fe‐N‐C exhibits a high Faradic efficiency for urea of 50.05% with a yield of 850.57 mg h‐1 g‐1 at ‐0.35 V (vs. RHE) in a flow cell. Moreover, Curea‐selectivity reaches to 100% and a near‐unity selectivity for the value‐added urea and NH3 is realized. The present results provide a valuable reference for the design of new catalysts for efficient synthesis of C‐N compounds in dilute NO2‐ solution.