First-principles study of CO2 and H2O adsorption on the anatase TiO2(101) surface: effect of Au doping†

Photocatalytic reduction of CO₂ will play a major role in future energy and environmental crisis. To investigate the adsorption mechanisms of CO₂ and H₂O molecules involved in the catalytic process on the surface of anatase titanium dioxide 101 (TiO₂(101)) and the influence of Au atom doping on their adsorption, first-principles density functional theory calculations were used. The results show that 1. Au atom doping stabilizes the structure of the catalyst system and reduces the band gap, facilitating the reaction of CO₂ and H₂O molecules. 2. The O site is the most stable adsorption site for the CO₂ molecule on the surface, and chemical adsorption occurs, leading to structural deformation during the adsorption process. The adsorption energy is the highest when the H₂O molecule is adsorbed parallel to the surface, and there is a bonding trend between H₂O and the surface. 3. The adsorption performances of CO₂ and H₂O molecules improve after Au atom doping. 4. Au atom doping creates stronger adsorption sites on the catalyst surface, with the two-coordinated O atoms near the Au atom becoming the preferred adsorption sites for both molecules. The revealed microscopic mechanism provides theoretical support for the design and manufacture of photocatalytic CO₂ reduction catalysts.