Sonochemical fabrication of mesoporous TiO2 inside diatom frustules for photocatalyst

Mesoporous titanium dioxide (TiO₂) has been assembled inside the macropores of diatom frustules by sonochemical condensation of titania precursor, and then thermal treated at an elevated temperature. The resulting hierarchical macro/mesoporous-structures of the TiO₂ inside diatom were confirmed by characterizations of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The amount of TiO₂ inside the periodic macropores of diatom was controlled by varying the sonication time. It was found that the resultant composite with only 30 wt% TiO₂ loading delivered a high photocatalytic performance, even better than that of pure P25. This is attributed to its hierarchical macro/mesoporous structure as it provides a large number of accessible active sites for efficient transportations of guest species to framework binding sites. Other macro/mesoporous structures with a nearly endless variety of functional chemistries and shapes are expected to be produced, leading to a range of novel applications in remediation, molecular transportation and environmental field by using this facile strategy.