Enhanced photocatalytic activities of vacuum activated TiO2 catalysts with Ti3+ and N co-doped

We employ a one-step vacuum activation method to obtain Ti3+ and N co-doped TiO2 photocatalysts with high reactivity under visible light. The prepared photocatalysts were characterized with XRD, UV-vis absorption spectra, XPS, EPR, and BET. The characterization results indicate that the co-doped photocatalysts have a relative small crystallite size and high surface area. After the vacuum activation, the Ti3+ is generated in the bulk of TiO2 and the nitrogen is transferred from the surface to the lattice of TiO2. The vacuum activated TiO2 catalysts have revealed an improvement over pure TiO2 under visible light irradiation both in optical absorption and photocatalytic activity. It suggests that vacuum activated procedure can not only produce Ti3+ in the bulk of TiO2 to improve its visible-light activity but also can be a good method to further introduce some anionic species for the doping such as nitrogen element which is good for band-gap narrowing. In addition, the enhanced visible-light photocatalytic activity of the catalyst does not rely on the sacrifice of the photocatalytic activity under UV-light irradiation. (C) 2015 Elsevier B.V. All rights reserved.