| AVS 63rd International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS+HC-TuA |
| Session: | Photocatalysis and Photochemistry at Surfaces |
| Presenter: | Shiliang Ma, University of Virginia |
| Authors: | S. Ma, University of Virginia M. Reish, University of Virginia Z. Zhang, University of Virginia I. Harrison, University of Virginia J.T. Yates, Jr., University of Virginia |
| Correspondent: | Click to Email |
By employing photoluminescence (PL) spectroscopy, it was found that oxygen adsorption on powdered TiO2 changes the band bending of anatase in different ways. On the one hand, oxygen exposure leads to molecular chemisorption of oxygen molecules, which take up negative charge, but can be reversibly removed by ultraviolet photodesorption from the TiO2 surface. Molecular chemisorption of oxygen molecules increases the upward band bending of TiO2 and decreases the PL emission. On the one hand, oxygen can adsorb through irreversible reaction with defects, which occurs through an intermediate state of molecularly chemisorption, reducing the intrinsic upward band bending at the TiO2 surface resulting in PL emission increase. Since band bending plays an important role in charge carrier migration to the surface, this finding that oxygen adsorption can have two different effects on the band bending of TiO2 provides a new perspective on how oxygen and oxygen vacancies may modulate photocatalytic reaction efficiencies.