Paper SS-FrM4
Oxygen Adatom Formation and Charge Transfer upon O₂ Dissociation on Reduced TiO₂(110)

Friday, October 22, 2010, 9:20 am, Room Santa Ana

Combination of the statistical analysis by s canning tunneling microscopy and density functional theory calculations has been used to investigate the initial stages of molecular oxygen dissociation on the reduced TiO₂(110) surface at 300 K . Major O₂ dissociation channel results in the bridging O vacancy (V_O) healing and deposition of a single O adatom (O_a), while minor channel results in formation of O_a pair on regular Ti sites. For latter channel, an intermediate, metastable nearest-neighbor O_a-O_a configuration is observed after O₂ dissociation. This initial configuration is destabilized by Coulomb repulsion of charged O_a’s that separate further along the Ti row into energetically more favorable second-nearest neighbor configuration. The potential energy profile calculated for O₂ dissociation on Ti rows and following O_a’s separation strongly supports the experimental observations. Our results also suggest that the itinerant electrons associated with the V_O‘s are being utilized in the O₂ dissociation process at the Ti rows, whereas at least two oxygen vacancies per O₂ molecule are required in order for this process to become viable. Overall, the electrons originating from V_O’s provide a larger fraction of charge required for O₂ dissociation, while a smaller fraction can be attributed to Ti interstitials.

[1] Du, Y.; Dohnalek, Z.; Lyubinetsky, I. J. Phys. Chem. C 2008, 112, 2649.

[2] Du, Y.; Deskins, N. A.; Zhang, Z.; Dohnalek, Z.; Dupuis, M.; Lyubinetsky, I. Phys. Chem. Chem. Phys.

2010, DOI: 10.1039/C000250J.