Electron traps and their effect on the surface chemistry of TiO2(110).
Oxygen vacancies on metal oxide surfaces have long been thought to play a key role in the surface chemistry. Such processes have been directly visualized in the case of the model photocatalyst surface TiO(2)(110) in reactions with water and molecular oxygen. These vacancies have been assumed to be neutral in calculations of the surface properties. However, by comparing experimental and simulated scanning tunneling microscopy images and spectra, we show that oxygen vacancies act as trapping centers and are negatively charged. We demonstrate that charging the defect significantly affects the reactivity by following the reaction of molecular oxygen with surface hydroxyl formed by water dissociation at the vacancies. Calculations with electronically charged hydroxyl favor a condensation reaction forming water and surface oxygen adatoms, in line with experimental observations. This contrasts with simulations using neutral hydroxyl where hydrogen peroxide is found to be the most stable product.
Department of Chemistry, University College London, London Centre for Nanotechnology, 17-19 Gordon Street, London WC1H 0AH, UK.
Anthoula C
AC
Papageorgiou
Nikolaos S
NS
Beglitis
Chi L
CL
Pang
Gilberto
G
Teobaldi
Gregory
G
Cabailh
Qiao
Q
Chen
Andrew J
AJ
Fisher
Werner A
WA
Hofer
Geoff
G
Thornton
D000465:Algorithms; D003198:Computer Simulation; D004583:Electrons; D017665:Hydroxyl Radical / Q000737:chemistry; D016252:Microscopy, Scanning Tunneling; D008956:Models, Chemical; D008958:Models, Molecular; D010100:Oxygen / Q000737:chemistry*; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D014867:Water; C009495:titanium dioxide; D017665:Hydroxyl Radical; D014025:Titanium; D010100:Oxygen