Catalyst and gas diffusion electrode design toward C–N coupling for urea electrosynthesis

The electrocatalytic C–N coupling reaction involving carbon dioxide (CO 2 ) and nitrogenous small molecules has recently emerged as a subject of considerable interest within the field of urea synthesis. This approach has the potential to facilitate the clean, sustainable production of urea, thereby contributing to the attainment of carbon neutrality and the advancement of artificial nitrogen cycling. Nevertheless, electrocatalytic urea synthesis still faces significant challenges due to the difficulty of balancing the co-activation of carbon and nitrogen sources and the subsequent catalytic C–N coupling of in situ -generated species, as well as competing reactions. To overcome these challenges, there is a growing emphasis on the research of gas diffusion electrodes (GDEs) and the design of electrode materials. This article provides a comprehensive review of the C–N coupling mechanisms, the classification of catalysts, the electrocatalyst design and optimization strategies, and the fundamental functions and importance of GDEs in electrocatalytic C–N coupling reactions. It also provides insights and perspectives on the major challenges and future research directions for GDEs and electrocatalysts in electrocatalytic urea synthesis. • In-depth analysis of modulating the reactivity and reaction pathways in C–N coupling is included. • The catalysts and optimization strategies are comprehensively reviewed. • The role of GDEs is systematically discussed, along with GDE applications and interfaces in various reactors. • Ongoing and future research confront several bottlenecks and challenges, which are emphasized.