Photocatalytic Oxidation of Acetone Over High Thermally Stable TiO(2) Nanosheets With Exposed (001) Facets

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