Impact of Si and Zr addition on the surface defect and photocatalytic activity of the nanocrystalline TiO2 synthesized by the solvothermal method

In the present work, the effects of Si and Zr addition on the surface defect and photocatalytic activity of the solvothermal-derived TiO2 were investigated. The metal-doped TiO2 samples were prepared with the molar ratio Si/Ti and Zr/Ti ranging from 0.002 to 0.1 and were subjected to two different cooling temperatures (room temperature and 77 K) after calcination as a post-synthesis treatment. The presence of a small amount of metal dopant caused a slight change in the TiO2 crystallite and BET surface area (ranging from 7.8 to 10.6 nm and corresponding surface area 95 to 159 m2/g). The photocatalytic activity of TiO2 did not depend solely on the surface area but rather affected by the concentration of Ti3+ on the catalyst surface as shown by a linear ascending trend of the ethylene conversion and the amount of Ti3+/surface area of the catalysts. It is noted that addition of Zr had more positive effect than Si and the effect of post-treatment on the photocatalytic activity of TiO2 catalysts was more pronounced than the addition of metal dopants.