Uncovering the Mechanism for Urea Electrochemical Synthesis by Coupling N2 and CO2 on Mo2C-MXene

Abstract

In this work, the catalytic activities of Mo2C-MXene for the co-synthesis of urea from N2 and CO2 are reported by well-defined density functional theory (DFT) method. The calculated results show that the presence of surface functional groups is not conducive to the CO2/N2 (C/N) coupling process in urea synthesis reaction. The exposed Mo2C on the surface can realize urea synthesis at the limit point of 0.69 eV, but the large transition state energy barrier (1.50 eV) indicates that bare Mo2C is not a promising urea catalyst. Loading single atoms can improve the urea synthesis performance of bare Mo2C. The energy barrier of urea synthesis reaction and the transition state energy barrier of C/N coupling reaction have dropped significantly by the atomic loading of Fe and Ti on bare Mo2C. Moreover, Ti doped Mo2C exhibits better catalytic selectivity toward urea production, making it an excellent catalyst for urea synthesis. We hope this work can pave the way for the electrochemical synthesis of urea.