A Defect Engineered Electrocatalyst that Promotes High-Efficiency Urea Synthesis under Ambient Conditions

Synthesizing urea from nitrate and carbon dioxide through an electrocatalysis approach under ambient conditions is extraordinarily sustainable. However, this approach still lacks electrocatalysts developed with high catalytic efficiencies, which is a key challenge. Here, we report the high-efficiency electrocatalytic synthesis of urea using indium oxyhydroxide with oxygen vacancy defects, which enables selective C-N coupling toward standout electrocatalytic urea synthesis activity. Analysis by operando synchrotron radiation-Fourier transform infrared spectroscopy showcases that *CO2NH2 protonation is the potential-determining step for the overall urea formation process. As such, defect engineering is employed to lower the energy barrier for the protonation of the *CO2NH2 intermediate to accelerate urea synthesis. Consequently, the defect-engineered catalyst delivers a high Faradaic efficiency of 51.0%. In conjunction with an in-depth study on the catalytic mechanism, this design strategy may facilitate the exploration of advanced catalysts for electrochemical urea synthesis and other sustainable applications. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) C.Y. acknowledges funding supported by the National Natural Science Foundation of China (Grant 52101246) and the Fundamental Research Funds for the Central Universities (Grant 5710010721). Q.Y. acknowledges funding support from Singapore MOE AcRF Tier 1 Grant 2020-T1-001-031 and Singapore A*STAR project A19D9a0096. G.Y. acknowledges funding support from the Camille Dreyfus TeacherScholar Award and Welch Foundation Award F-1861. The authors acknowledge computing resources from the National Supercomputing Centre, Singapore. This work is also supported by the Users with Excellence program of Hefei Science Center of CAS (2020HSC-UE003) and the Fundamental Research Funds for the Central Universities (WK2310000099).