Correlations among defect type, photoconductivity and photoreactivity of doped TiO2

Abstract

The electrical conductivity (sigma), photoconductivity and photocatalytic reactivity in doped crystalline TiO2 were measured as a function of the oxygen partial pressure (Po-2), temperature, doping type and UV irradiation. The Po, dependence of sigma suggests that the predominant atomic defects in pure TiO2 are oxygen vacancies (V-(o)double over dot) and interstitial titanium ions (Ti-(i) triple over dot), but the dominant defect is changed with Po-2 and temperature. The photoexcited electrons in reduced and/or n-type doped TiO2 enhance both the photoconductivity and the photocatalytic reactivity by the reduction process. Therefore, these behaviors are strongly dependent on the electron concentration.