Oxygen-vacancy-rich Ni/CeO2: UiO-66-derived high-efficiency catalyst for low-temperature CO2 methanation

Methanation serves as a strategy for the comprehensive utilization of CO2, however, designing catalysts with superior low-temperature activity and sintering resistance remains a significant challenge. Oxygen vacancies can greatly influence the catalytic activity, thus constructing catalysts with abundant oxygen vacancies is crucial for high-performance CO2 methanation reaction. In this study, a defect engineering strategy was employed to synthesize 15Ni/CeO2-U catalyst. Based on the characterization results from Raman spectroscopy and quasi in-situ XPS, the 15Ni/CeO2-U catalyst possesses an exceptionally abundant oxygen vacancies compared to the 15Ni/CeO2 catalyst. Additionally, the catalyst exhibited highly dispersed active sites, moderate metal-support interaction strength, and a smaller Ni nanoparticle size. These factors synergistically enhanced its performance in the low-temperature CO2 methanation reaction, achieving a CO2 conversion of 77.1 % at 200 °C, with selectivity and space–time yield for CH4 of 98.7 % and 204.0 mmol· gcat-1 ·h−1, respectively. The results indicate that it is one of the best low-temperature CO2 methanation catalysts to date. Density functional theory (DFT) calculations and in-situ DRIFTS analysis revealed that the presence of oxygen vacancies facilitates the further hydrogenation of CO2 to methane via the HCOO* pathway. This work offers a worthy strategy to constructing high-performance catalysts suitable for low-temperature CO2 methanation.