AUTHOR=Shi Ting , Duan Youyu , Lv Kangle , Hu Zhao , Li Qin , Li Mei , Li Xiaofang 

TITLE=Photocatalytic Oxidation of Acetone Over High Thermally Stable TiO2 Nanosheets With Exposed (001) Facets

JOURNAL=Frontiers in Chemistry

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2018.00175

DOI=10.3389/fchem.2018.00175

ISSN=2296-2646

ABSTRACT=<p>Anatase TiO<sub>2</sub> (A-TiO<sub>2</sub>) usually exhibits superior photocatalytic activity than rutile TiO<sub>2</sub> (R-TiO<sub>2</sub>). However, the phase transformation from A-TiO<sub>2</sub> to R-TiO<sub>2</sub> will inevitably happens when the calcination temperature is up to 600°C, which hampers the practical applications of TiO<sub>2</sub> photocatalysis in hyperthermal situations. In this paper, high energy faceted TiO<sub>2</sub> nanosheets (TiO<sub>2</sub>-NSs) with super thermal stability was prepared by calcination of TiOF<sub>2</sub> cubes. With increase in the calcination temperature from 300 to 600°C, TiOF<sub>2</sub> transforms into TiO<sub>2</sub> hollow nanoboxes (TiO<sub>2</sub>-HNBs) assembly from TiO<sub>2</sub>-NSs via Ostwald Rippening process. Almost all of the TiO<sub>2</sub>-HNBs are disassembled into discrete TiO<sub>2</sub>-NSs when calcination temperature is higher than 700°C. Phase transformation from A-TiO<sub>2</sub> to R-TiO<sub>2</sub> begins at 1000°C. Only when the calcination temperature is higher than 1200°C can all the TiO<sub>2</sub>-NSs transforms into R-TiO<sub>2</sub>. The 500°C-calcined sample (T500) exhibits the highest photoreactivity toward acetone oxidation possibly because of the production of high energy TiO<sub>2</sub>-NSs with exposed high energy (001) facets and the surface adsorbed fluorine. Surface oxygen vacancy, due to the heat-induced removal of surface adsorbed fluoride ions, is responsible for the high thermal stability of TiO<sub>2</sub>-NSs which are prepared by calcination of TiOF<sub>2</sub> cubes.</p>