Mechanisms and Advanced Characterizations for Urea Electrosynthesis

ABSTRACT Urea synthesis by the electrochemical coupling of carbon‐containing species (such as CO 2 , CO, and HCOOH) with nitrogenous species (such as N 2 , NO, NO 2 − , and NO 3 − ) under ambient conditions has attracted increasing attention very currently, owing to its potential to advance carbon/nitrogen neutrality and mitigate environmental pollution. However, sluggish reactant adsorption, complex reaction pathways, and multiple competing side reactions severely limit the Faradaic efficiency and production rate toward urea electrosynthesis. Extensive efforts should be devoted to providing reasonable guidance for the development of highly active and selective electrocatalysts. To this end, the in‐depth mechanisms of urea electrosynthesis are firstly reviewed in this review, including the C–N coupling and the hydrogenation pathways involved. Given the importance of in situ techniques in mimicking the realistic operating conditions for elucidating reaction mechanisms, we also summarize the principles and applications of commonly used advanced characterizations. Finally, the challenges and future perspectives for the electrochemical urea production via C–N coupling are further discussed.