Density Functional Theory (DFT) calculations within the Generalized Gradient Approximation (GGA) and the GGA + U approach are carried out to investigate the adsorption of O2 on anatase (101) surfaces having subsurface oxygen vacancies. Our results show that O2 adsorption is strongly enhanced at sites close to the subsurface defect, whereas dissociation is unfavorable at all sites. The adsorption is accompanied by the transfer of the defect electrons to O2-derived electronic states in the anatase surface band gap. Peroxide species (O22-, O-O = 1.48 ) are stable when the number of adsorbed O2 molecules is less or equal the number of defects, whereas superoxide species (O2-, O-O = 1.33 ) become more favorable at coverages exceeding approximately 1.5 O 2 molecules per oxygen vacancy.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry