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

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-09, Vol.496, p.154063, Article 154063
• Main Authors: Mao, Yini, Gou, Qiao, Lv, Shengmei, Zhao, Niandan, Jiang, Yimin, Shen, Wei, Li, Ming, He, Rongxing
• Format: Article
• Language: English
• Subjects: CuO/In2O3; Heterogeneous interface; Oxygen vacancy; Synergistic catalysis; Urea
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.154063

The heterogeneous interface and the oxygen vacancy each play their own roles and cooperate with each other to synergistically enhance the catalytic performance: oxygen vacancy greatly facilitates the NO3− reduction process to prepare sufficient nitrogen-containing intermediates for the synthesis of urea, and also provides a positive boost in the electron transfer capacity of the catalyst; the heterogeneous interface cause the electronic modulation of CuO/In2O3, which promotes the adsorption, activation and reduction of CO2, as well as the C−N coupling reaction between *NH2 and *CO to generate *CONH2 and then urea. [Display omitted] •CuO/In2O3 heterojunction enriched with oxygen vacancies was designed.•The oxygen vacancies greatly facilitate the NO3− reduction process and also provide a positive boost in the electron transfer capacity of the catalyst.•The heterogeneous interfaces enable electronic modulation, facilitating the adsorption, activation and reduction of CO2, as well as the C-N coupling reaction between *NH2 and *CO.•The synergistic interaction between heterogeneous interfaces and oxygen vacancies is responsible for the major part of the high efficiency of the catalyst. 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