Preparation and Enhanced Photocatalytic Activity of TiO₂ Nanocrystals with Internal Pores

Anatase TiO2 nanocrystals with internal pores are prepared by a novel facile microwave-assisted hydrolysis of a mixture of TiOCl2 and HF aqueous solutions, followed by calcination at 400 °C. The TiO2 nanocrystals with internal pores are characterized by XRD, TEM, SEM, BET, EDS, and XPS. The formation mechanism of the TiO2 nanocrystals with internal pores is discussed by investigating the role of fluorine and the calcination. The photocatalytic measurement shows that the TiO2 nanocrystals with internal pores exhibit much higher photocatalytic activity for the photodegradation of crystal violet, methyl orange, and 4-chlorophenol than the TiO2 solid nanocrystals. The photocatalytic enhancement is due to the fluorination of TiO2 nanocrystals as well as its unique hollow nanostructure, which results in the higher separation efficiency of photogenerated electrons and holes in the TiO2 nanocrystals with internal pores than in its solid counterpart.