The location of excess electrons on H2O/TiO2(110) surface and its role in the surface reactions

Excess electrons play a key role in many of the properties of Titanium dioxide (TiO2). Understanding their behaviour is important for improving the performance of TiO2 in energy-related applications. Here, we describe a DFT + U study of the locations of the unpaired electron (UPE) on rutile TiO2 (110) (R-TiO2 (110)) surface and H2O/R-TiO2 (110) surface. Our results show that the subsurface are preferred with R-TiO2 (110) surface. In contrast to previous studies, we find that the UPE tends to migrate to the surface H2O-Ti-5c (the five-coordinated titanium (Ti-5c) at surface with H2O adsorption) with the increasing of H2O coverage and UPE concentration. In addition, we have shown that the UPE plays an important role in the O-H bond dissociation and other important elementary reactions in photo-catalytic H2O dissociation on R-TiO2 (110) such as H, OH and H-2 desorption. Specifically, it enhances the O-H bond dissociation, as well as H and H-2 desorption from bridging hydroxyl and Ti-5c-OH (the Ti-5c with OH adsorption), but hinders the OH and H desorption from Ti-5c. We believe our results afford a further understanding of the adsorbent dependent UPE migration, and the role of UPE in the surface reactions. [GRAPHICS] .