Understanding and Regulating C–N Coupling Pathways for Electrocatalytic Urea Synthesis From CO 2 and NO 3 − /NO 2 −

to synthesize urea is a promising alternative to the traditional urea production process. However, the complexity of the reaction pathway hinders clear identification of C-N coupling mechanisms, thereby limiting the ability to guide catalyst design. Therefore, to design catalysts with improved performance, it is necessary to deepen the understanding of the urea synthesis process, particularly the C-N coupling step. This review summarises and discusses the current mechanistic insights into C-N coupling. Several representative C-N coupling pathways reported to date are reviewed and assessed in detail. Intermediate-regulation strategies on both the carbon and nitrogen sides for promoting C-N coupling are discussed. In addition, commonly employed characterization techniques for elucidating the reaction mechanism are reviewed. Finally, this review provides perspectives on further exploring C-N coupling mechanisms.