Boosting CO₂ methanation activity on Ru/TiO₂ catalysts by exposing (001) facets of anatase TiO₂

Catalytic reduction of CO₂ to methane has been recognized as one of the most important strategic reactions to produce highly valuable chemicals and for storage of renewable energy (power-to-gas). This study demonstrates a crystal facet-dependent catalytic reduction of CO₂ to CH₄ on ruthenium nanoparticles deposited over TiO₂ nanocrystal with exposed (001) and (101) facets. Compared with TiO₂ (101) nanocrystal with the same Ru loading, Ru nanoparticles supported by TiO₂ (001) exhibited a highly enhanced CO₂ conversion rate and significantly improved methanation reactivity, along with a considerable durability. The physicochemical properties of the samples were characterized by HR-TEM, XRD, BET, FT-IR, UV-vis, Raman, ICP, and temperature-programmed reaction with CO₂, and CO₂ + H₂. In view of the difference in catalytic activity and the physicochemical properties of the supported Ru/TiO₂ catalysts, the results uncovered that the nature of the catalyst support of Ru/TiO₂ strongly affected the dispersion of Ru species and the synergistic effect between Ru and underlying TiO₂ supporting materials due to the strong metal-support interaction, and thus affected their capability to activate CO₂ and determined the catalytic activity for CO₂ methanation. Our work demonstrated the important role of the exposed crystal facets of the underlying support and the resulting Ru particle which had a large effect on CO₂ methanation.