Remarkable Activity of 002 Facet of Ruthenium Nanoparticles Grown on Graphene Films on the Photocatalytic CO₂ Methanation

Abstract In the context of diminishing atmospheric CO₂ emissions, there is an urgent need to develop processes that can be carried out at a scale commensurate with appropriate CO₂ volumes. One possible reaction is the transformation of CO₂ to methane (Sabatier reaction). Due to its chemical stability, catalytic CO₂ hydrogenation to methane is carried out at temperatures of 450 °C or higher and pressures above 5 bars, thus, requiring a significant energy input. One alternative possibility to conventional thermal catalysis is the use of solar light as the primary energy, performing the photocatalytic CO₂ hydrogenation. In this broad context, the present study shows the photocatalytic activity of nanometric films of oriented Ru nanoparticles (NPs) strongly grafted on defective graphene. These graphene films (thinner than 20 nm) containing Ru NPs nanoplatelets (less than 2 nanomol_Ru/cm²) are among the most active photocatalysts ever prepared for CO₂ hydrogenation and operate through photoinduced charge separation.