Hydrothermal synthesis and photocatalytic activity of nanocrystalline TiO 2 powders in ethanol–water mixed solutions

Abstract

Bimodal mesoporous nanocrystalline TiO 2 powders were synthesized by a hydrothermal method using tetrabutylorthotitanate as precursor in ethanol–water mixed solutions. The as-prepared TiO 2 powders were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and N 2 adsorption–desorption measurements. The photocatalytic activity of the as-prepared TiO 2 powders was evaluated by the photocatalytic degradation of acetone under UV-light irradiation at room temperature in air. The effects of alcohol content on the microstructures and photocatalytic activity of the TiO 2 powders were investigated and discussed. The molar ratios of EtOH to H 2O obviously influenced the crystallization, crystallite size, BET specific surface areas and photocatalytic activity of the prepared TiO 2 powders. Hydrothermal treatment enhanced the phase transformation of the TiO 2 powders from amorphous to anatase and crystallization. It was found that the photocatalytic activity of TiO 2 powders prepared at 150–200 °C for 3–24 h in an ethanol–water mixed solution greatly exceeded that of Degussa P25. All TiO 2 powders after hydrothermal treatment showed bimodal pore-size distributions in the mesoporous region: one was intra-aggregated pores with maximum pore diameters of ca. 2–8 nm and the other inter-aggregated ones with maximum pore diameters of ca. 41–48 nm.