Nanoparticles of TiO2 doped with different amounts of Zn were prepared by a sol-gel method and were mainly characterized by means of X-ray photo-electron spectroscopy, photoluminescence, and surface photovoltage spectrum. The effects of surface oxygen vacancies of Zn-doped TiO2 nanoparticles on photophysical and photocatalytic processes were investigated along with their inherent relationships. The results showed that the surface oxygen vacancies easily bound photo-induced electrons to give rise to photoluminescence signals. The surface oxygen vacancies could result in an interesting sub-band surface photovoltage spectrum response near the band edge in the TiO2 sample consisting of much anatase and little rutile, except for an obvious band-to-band surface photovoltage spectrum response. Moreover, the intensities of photoluminescence and surface photovoltage spectrum signals of TiO2, as well as the photocatalytic activity for degrading phenol solution, could be enhanced by doping an appropriate amount of Zn. These improvements were mainly attributed to the increase in the surface oxygen vacancy amount. It could be suggested that the surface oxygen vacancies should play an important role during the processes of photoluminescence, surface photovoltage, and photocatalytic reactions, and, for the as-prepared TiO2 samples doped with different amounts of Zn by thermal treatment at 550C, the larger the surface oxygen vacancy amount, the stronger the photoluminescence and surface photovoltage spectrum signal, and the higher the photocatalytic activity.

Effects of Surface Oxygen Vacancies on Photophysical and Photochemical Processes of Zn-Doped TiO2 Nanoparticles and Their Relationships. Jing, L., Xin, B., Yuan, F., Xue, L., Wang, B., Fu, H.: Journal of Physical Chemistry B, 2006, 110[36], 17860-5