Ab initio R1 mechanism of photostimulated oxygen isotope exchange reaction on a defect TiO2 surface: The case of terminal oxygen atom exchange

摘要

Based on density functional theory we propose R1 mechanism of photostimulated oxygen isotope exchange (POIEx) reaction between (OO)-O-16-O-18 and terminal oxygen atom of a defect TiO2 surface, which is modeled by amorphous Ti8O16 nanocluster in excited S-1 electronic state. The proposed mechanism involves four adsorption intermediates and five transition states. The computed activation energy of the POIEx equals 0.24 eV. The computed g-tensors of the predicted ozonide O-3-chemisorption species match well EPR data on O-2 adsorption on UV-irradiated nanocrystalline TiO2. This match serves a mean of justification of the proposed R1 mechanism of the POIEx reaction. In addition, it is found that the proposed R1 POlEx reaction's mechanism differs from R1 mechanism of thereto-assisted OlEx reaction on a surface of supported vanadium oxide catalyst VOx/TiO2 reported earlier. (C) 2017 Elsevier B.V. All rights reserved.