Abundant interfacial and intrinsic oxygen vacancies enabling small nickel/ceria nanocrystal efficient CO2 methanation

Smaller nano-sizes typically result in supported catalysts with abundant interfacial and intrinsic oxygen vacancies for better adsorption and activation of small molecules, including CO₂, leading to improved efficiency of CO₂ methanation. Here, Ni/CeO₂-S with the smaller nano-size of around 4.2 nm is used to catalyze CO₂ methanation, which exhibits significantly enhanced activity compared to larger nano-sized Ni/CeO₂-L catalyst, even surpassing the most majority of previously reported catalysts using CeO₂ as the support or Ni as the active metal. The coexistence of interfacial defects and intrinsic oxygen vacancies allows for enhanced adsorption and activation of CO₂ molecules as well as H spillover, resulting in such improved CO₂ methanation. In-situ DRIFTS demonstrate a nearly sole Formate pathway on Ni/CeO₂-S for efficient CO₂ hydrogenation. This research provides valuable insights into the reaction mechanism over a small nanosize supported catalyst.