Effect of Vacuum-Sealed Annealing and Ice-Water Quenching on the Structure and Photocatalytic Acetone Oxidations of Nano-TiO 2 Materials.

In the current research, P25 TiO 2 materials sealed in quartz vacuum tubes were subject to annealing and ice-water post-quenching, with the effects on TiO 2 structures, morphology, and photocatalytic activity being studied. It is shown that the vacuum-sealed annealing can lead to a decrease in the crystallinity and temperature of anatase-to-rutile phase transition. A disorder layer is formed over TiO 2 nanoparticles, and the TiO 2 lattices are distorted between the disorder layer and crystalline core. The ice-water post-quenching almost has no effect on the crystalline structure and morphology of TiO 2 . It can be seen that the vacuum-sealed annealing can generate more defects, and the electrons are mainly localized at lattice Ti sites, as well as the percentage of bulk oxygen defects is also increased. Although further ice-water post-quenching can introduce more defects in TiO 2 , it does not affect the electron localization and defect distribution. The vacuum-sealed annealing process can increase the photocatalytic acetone oxidations of the anatase phase TiO 2 to some extent, possibly because of the defect generation and Ti 3+ site formation; the further ice-water quenching leads to a decrease in the photocatalytic activity because more defects are introduced.