Dual Regulation of Oxygen Vacancies and Metal−Support Interaction in Ni/NixCeO2-γ for Synergistic Enhancement of Low-Temperature CO2 Methanation

Catalytic CO 2 methanation converts CO 2 with hydrogen into methane, enabling carbon recycling and chemical energy storage. However, the precise roles and synergy of critical active sites, oxygen vacancies and metal–support interfaces remain elusive in CO 2 methanation, impeding the development of highly active and selective low-temperature catalysts. Based on density functional theory calculations, herein, Ni-doped CeO 2 supports were designed to load Ni nanoparticles for constructing Ni/Ni x CeO 2-γ catalysts. With 2 mol % Ni doping, the Ni/Ni 0.02 CeO 2-γ catalyst exhibited 75.5% CO 2 conversion and 100% CH 4 selectivity at 250 ° C, and maintained its activity over 200 h at 300 ° C. Compared to Ni/CeO 2 , Ni/Ni 0.02 CeO 2-γ features smaller CeO 2 nanoparticles, higher oxygen vacancy concentration, and stronger metal–support interaction. The abundant oxygen vacancies create frustrated Lewis pairs with adjacent basic sites (e.g., hydroxyls and lattice oxygen) for effective CO 2 adsorption and activation, while the strong metal–support interaction facilitated the adsorption and dissociation of H 2 on the metallic Ni sites. Consequently, the above synergy boosted key steps including hydrogen spillover and intermediate hydrogenation, resulting in a marked improvement in the CO 2 methanation rate at low temperatures. The in situ diffuse-reflectance infrared Fourier transform spectroscopy revealed that the formate pathway served as the principal reaction mechanism for CO 2 methanation over Ni/Ni 0.02 CeO 2-γ . This study elucidates the role of oxygen vacancy-mediated synergy in low-temperature CO 2 methanation and offers a strategy for designing CO 2 hydrogenation catalysts.