a This study differs from previous studies of TiO 2 /SiO 2 in that 0.5-10 mm microsized TiO 2 -rutile based catalysts (TR catalysts) with varying proportions of titanium and silicon were synthesized using a onestep modified hydrothermal method. At Ti/Si ¼ 1/9, a two-dimensional channel-structured catalyst with a morphology resembling that of SBA-15 was obtained. In contrast, at Ti/Si ¼ 3/7 or 5/5, a threedimensional porous structure was formed, and Ti-O-Si-C bonds appeared. The structure of the TR catalyst transformed due to the decrease in C-Si bond content and the increase in C-C bond content with increasing Ti/Si ratio. The results indicated that the rutile phase was the main crystal phase of the TR catalyst. The small crystal size and large rutile phase content of the mesoporous TR catalyst contributed to the low band gap energy below 3.0 eV. Under 2 Â 10 W lamp irradiation with either UVA or visible light, the three TR catalysts showed better formaldehyde (HCHO) removal efficiency than P25. Overall, the Pt/TR catalyst is a potential material for pollutant removal and can be easily separated from the pollutant removal system since the catalysts are microsized.