Catalytic behavior of supported Ru nanoparticles on the (101) and (001) facets of anatase TiO2

Ru/TiO2 heterogeneous catalysts were prepared by immobilizing Ru nanoparticles onto the (101) and (001) facets of anatase TiO2 substrate, and the influence of metal-support interactions on the catalytic behavior of Ru/TiO2 towards CO2 methanation was studied from the viewpoint of electronic structure. Structural investigations based on temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS) indicate that a stronger metal-support interaction occurs between Ru and (101) facet in contrast to the Ru and (001) one. This gives rise to an enhancement in CO2 adsorption as well as spill-over hydrogen at the interface of Ru/TiO2(101), accounting for its largely enhanced catalytic activity towards CO2 methanation. In addition, a theoretical study based on density functional theory (DFT) calculations reveals that the Ru nanoparticles supported on the (101) plane have a relatively lower activation energy for CO dissociation (the rate-determining step), which results in their high activity toward CO2 methanation reaction.