Unique adsorption behaviors of NO and O2 at hydrogenated anatase TiO2(101)

Titanium dioxide (TiO₂) is one of the most widely studied transition metal oxides, especially for its unique performances in heterogeneous photocatalysis. Different phases of TiO₂ have been found to exhibit different photo-activities, though the origins are still not fully understood. In this work, we use the density functional theory (DFT) calculations, corrected by on-site Coulomb and long-range dispersion interactions, to study the adsorptions of nitric oxide (NO) and oxygen (O₂) molecules on the clean and hydrogenated anatase TiO₂(101) surfaces. We also compare the detailed calculated results regarding their structural, energetic and electronic properties with those obtained at rutile TiO₂(110). It has been found that the behaviors of the surface localized electrons being transferred from adsorbed H, as well as the adsorption behaviors of NO and O₂ are quite different at the two surfaces, which can be attributed to their characteristic local bonding structures around the surface hydroxyl. These results may also help explain the different photocatalytic activities of these two main facets of anatase and rutile TiO₂