One-pot hydrothermal synthesis and enhanced photocatalytic activity of trifluoroacetic acid modified TiO2 hollow microspheres

Trifluoroacetic acid (TFA) modified TiO2 (TFA-TiO2) hollow microspheres were prepared by one-pot hydrothermal treatment of Ti(SO4)(2) in the presence of TFA at 180 degrees C for 12 h. The prepared samples were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, N-2 adsorption-desorption isotherms and Fourier transform infrared. The production rates of (OH)-O-center dot on the surface of UV-illuminated TiO2 were detected by a photoluminescence (PL) method using terephthalic acid (TA) as probe molecule. The photocatalytic activity was evaluated by the photocatalytic decomposition of acetone in air under UV light illumination. The results show that TFA not only induces the formation of hollow microspheres, but also enhances their crystallization. The molar ratios of TFA to Ti(SO4)(2) (R) have a great influence on photocatalytic activity. When R is in the range of 0.5-5, the photocatalytic activity of the samples is higher than that of commercial Degussa P25 TiO2 powders (P25) and pure TiO2 samples. At R = 2, the photocatalytic activity of the sample reaches the highest and exceeds that of P25 by a factor of more than two times. This is ascribed to the fact that the former has hollow interior and bimodal mesoporous shells enhancing harvesting of light and the transfer and transport of reactant and product molecules, also, the surface-adsorbed TFA can reduce the recombination of photo-generated electrons and holes. (C) 2010 Elsevier B.V. All rights reserved.