文摘
Photoreduction of CO2 for fuel production is considered to be an ultimate solution to today’s energy crisis. Platinum (Pt) particles are known to promote photocatalysis reactions when loaded on the surface of titanium dioxide (TiO2). In this study, we investigate the initial step of the reduction process of CO2 with water, i.e., the formation of formate, HCOO–, from surface bound CO2 and H2O on rutile TiO2(110) in terms of energetics of initial and final states using density functional theory calculations. To understand the role of a Pt cocatalyst, chemisorption energies of HCOO and OH on TiO2(110) are investigated with and without a Pt cluster. It is revealed that free electrons provided by the Pt cluster dramatically decrease the chemisorption energy thanks to the electron transfer from high-lying Pt states to unoccupied valence states induced by the adsorbates, which facilitates ionization of HCOO– and OH– on the TiO2 surface near the Pt cluster. Direct adsorption of HCOO and OH on the surface of the Pt cluster is also energetically favored.