Recent progress in electrochemical synthesis of urea through C-N coupling reactions

The traditional industry synthesizes urea through the reaction of NH3 and CO2 under high temperatures and pressure. Electrochemical catalysis, which could replace the traditional ammonia synthesis route, i.e., co-reduces carbon dioxide with nitrogen sources [nitrite (NO2-), nitrate (NO3-), nitrogen (N2), and nitric oxide (NO)] to synthesize urea, is a promising strategy for the synthesize of urea under environmental conditions. Unlike traditional industry routes, electrochemical catalysis urea synthesis is beneficial for both resource utilization and environmental protection. Herein, the recent research progress of electrocatalytic urea synthesis is summarized, with emphasis on the design and preparation of the catalyst for the coupling of CO2 and nitrogen species directly to urea. The involved reaction mechanism of C-N coupling is generalized and discussed. Furthermore, the difficulties and challenges at the present stage are summarized, and the development direction of electrocatalytic synthesis of urea is prospected.