부산대학교 도서관

The electrocatalytic synthesis of high-value-added urea by activating N2and CO2is a green synthesis technology that has achieved carbon neutrality. However, the chemical adsorption and C–N coupling ability of N2and CO2on the surface of the catalyst are generally poor, greatly limiting the improvement of electrocatalytic activity and selectivity in electrocatalytic urea synthesis. Herein, novel hierarchical mesoporous CeO2/Co3O4heterostructures are fabricated, and at an ultralow applied voltage of −0.2 V, the urea yield rate reaches 5.81 mmol g–1h–1, with a corresponding Faraday efficiency of 30.05%. The hierarchical mesoporous material effectively reduces the mass transfer resistance of reactants and intermediates, making it easier for them to access active centers. The emerging space-charge regions at the heterointerface generate local electrophilic and nucleophilic regions, facilitating CO2targeted adsorption in the electrophilic region and activation to produce *CO intermediates and N2targeted adsorption in the nucleophilic region and activation to generate *N ═ N* intermediates. Then, the electrons in the σ orbitals of *N ═ N* intermediates can be easily accepted by the empty egorbitals of Co3+in CeO2/Co3O4, which presents a low-spin state (LS: t2g6eg0). Subsequently, *CO couples with *N ═ N* to produce the key intermediate *NCON*. Interestingly, it was discovered through in situRaman spectroscopy that the CeO2/Co3O4catalyst has a reversible spinel structure before and after the electrocatalytic reaction, which is due to the surface reconstruction of the catalyst during the electrocatalytic reaction process, producing amorphous active cobalt oxides, which is beneficial for improving electrocatalytic activity.