Synergistic effects of heterogeneous interfaces and induced oxygen vacancies enhance the CuO/In2O3 performance in catalytic urea synthesis

Abstract

The industrial synthesis of urea suffers from the disadvantages of environmental pollution, high energy consumption, complicated process and unstable quality, etc. The preparation of urea by co-reduction of NO3− and CO2 using a suitable electrocatalyst at room temperature is a more environmentally friendly and energy-saving production method, which is of great significance for alleviating environmental pollution and energy crisis. In this work, CuO/In2O3 heterojunction was designed and synthesized, and the interface formation induced the generation of abundant oxygen vacancies. It is found that the oxygen vacancies enhance the activity of the material in NO3− reduction, while the heterogeneous interfaces prompt the material to show extraordinary ability in CO2 adsorption and activation, as well as promote the C−N coupling reaction. The synergistic effect between oxygen vacancies and heterogeneous interfaces enables CuO/In2O3 to exhibit excellent performance in the electrocatalytic synthesis of urea, with urea formation rate and Faraday efficiency of 794.72 µg mg−1h−1 and 9.11 %, respectively. The coupling mechanism of *NH2 + *CO2 is also proposed based on theoretical calculations, and the coupling energy barrier is only 0.27 eV. This work lays a foundation for the rational design of electrocatalysts for the efficient synthesis of urea.