Recent Progress and Challenges of Cu-Based Catalysts in Electrochemical Urea Synthesis with CO2 and Diverse Waste N Sources

Abstract

Urea is an essential nitrogen fertilizer and chemical, yet its conventional synthesis relies on high temperature and pressure, with high energy consumption and carbon dioxide (CO2) emissions. Electrochemical routes that couple CO2 reduction with waste nitrogen (N) sources offer a more sustainable alternative, but performance hinges on catalyst design. Copper (Cu)-based catalysts are promising because they lower activation barriers for CO2 and nitrate (NO3 -) reduction and can be tuned by alloying, grain-boundary engineering, and coordination regulation. Modified Cu catalysts, including atoms, nanoparticles, bulk metal, and metal-organic frameworks, with tailored electronic structures and lower energy barriers for key intermediates, exhibit good catalytic performance in terms of selectivity, yield rate, and applied potential. Nonetheless, critical challenges remain in resolving reaction mechanisms, establishing structure-activity relationships, and achieving practical performance. This review provides the first comprehensive analysis of Cu-based catalysts for electrochemical urea synthesis from CO2 and waste N nitrogen sources, and evaluates how catalyst structure, electrolytes, and operating conditions govern activity and selectivity, offering guidance for future design and application of Cu-based catalysts in electrochemical urea synthesis.