Preparation of porous titania particles via hot water or hydrothermal treatment of porous hydrous titania and their photocatalytic ability

抄録

The synthesis of porous titania microparticles with high specific surface area and sufficient photocatalytic activity is an important but challenging task. To this aim, micron-sized porous titania particles exhibiting photocatalytic activity comparable to that of titania nanoparticles were prepared in this study via hydrothermal treatment of porous hydrous titania particles. First, amorphous porous hydrous titania particles were prepared via hydrolysis of titanium alkoxide followed by partial dissolution of the particle surface by soaking in ethanol. Then, porous hydrous titania particles dried at 75 °C (Dry particles) and without drying (Wet particles) were respectively crystallized using hot water (<100 °C) or via hydrothermal treatment. Both types of particles were crystallized to anatase having a mesoporous structure and a preserved spherical outer shape under hydrothermal treatment. The mesoporous structure was controllable by tuning the treatment temperature, especially in the case of Wet particles. The porous titania particles prepared from Wet particles showed better photodegradation activity toward Evans blue under UV irradiation than those prepared from Dry particles, which is attributable to the distortion of titania crystallites prepared from Wet particles. In fact, despite their micron-order size, the photodegradation ability of Wet particles hydrothermally treated at 160 °C for 24 h was comparable to that of AEROXIDE^® TiO₂ P25.