Rapid synthesis of mesoporous TiO2 with high photocatalytic activity by ultrasound-induced agglomeration

Abstract

Three-dimensional and thermally stable mesoporous TiO2 was synthesized without the use of any surfactants via treatment with high intensity ultrasound irradiation for a short period of time. Monodispersed TiO2 sol particles were formed initially by ultrasound-assisted hydrolysis of acetic acid-modified titanium isopropoxide. Then, the mesoporous spherical or globular particles, which have a narrow pore size distribution, were produced by controlled condensation and agglomeration of these sol nanoparticles under high intensity ultrasound irradiation. The mesoporous TiO2 was characterized by XRD, TEM, nitrogen adsorption, TGA/DTA and FTIR. Low-angle XRD and TEM show the mesoporous TiO2 has a wormhole-like structure and a lack of long-range order. Nitrogen adsorption results indicate that the mesoporous TiO2 retains mesoporosity with a narrow pore size distribution and high surface area to at least 673 K. The thermal stability of mesoporous TiO2 is attributed to its thick inorganic walls, consisting of TiO2 nanoparticles. TGA study shows that this synthetic method is environmentally friendly. The photocatalytic activity of mesoporous TiO2 for the oxidation of acetone in air was measured. As-prepared mesoporous TiO2 has negligible activity due to its amorphous structure. Calcined mesoporous TiO2 shows better activity than commercial photocatalyst P25. The reasons for the high activity of mesoporous TiO2 are discussed.