Preparation of Porous TiO2 Hollow Spheres and Photodegradation of Methyl Orange

Abstract

Porous TiO₂ hollow spheres were prepared using carbon spheres, synthesized by hydrothermal method, as a template. The obtained carbon spheres coated with TiO₂ (C@TiO₂) was investigated by the TG-DTG technique to determine the thermal decomposition and subsequently was calcined at 500 and 550 ^oC. The prepared TiO₂ particles were characterized by XRD, SEM, TEM, and UV-vis spectroscopy techniques. The results from XRD showed that the porous TiO₂ hollow spheres calcined at 500 and 550 ^oC were polycrystalline with crystallite sizes of 13.6 and 18.7 nm, respectively. Optical absorption of the samples was studied under UV-visible light irradiation (from 200-800 nm). Energy band gap (Eg) of the porous TiO₂ hollow spheres calcined at 500 and 550 ^oC could be evaluated using absorption spectra, giving 3.09 and 3.12 eV, respectively. The photocatalytic activities of the calcined samples were studied using methyl orange solution under UVA irradiation (wavelength 320-400 nm). The results showed that the porous TiO₂ hollow spheres calcined at 550 ^oC exhibited higher photocatalytic activity than the sample calcined at 500 ^oC.