Heat treatment of nanometer anatase powder and its photocatalytic activity for degradation of acid red B dye under visible light irradiation

Abstract

The phase transformation of nanometer TiO2 powder from anatase to rutile was realized by heat treatment, and a new nanometer TiO2 photocatalyst that could be excited by visible light was obtained. The heat-treated TiO2 powder at different transition stage was characterized by powder x-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. The test of photocatalytic activity of the heat-treated TiO2 powder was carried out by the photocatalytic degradation of acid red B dye in aqueous solution under visible light irradiation. The nanometer anatase TiO2 heat-treated at 500°C for 30 min exhibited much higher activity than those of pure anatase and mechanically mixed (anatase and rutile) TiO2. The remarkable improvement of photocatalytic activity was mainly illustrated by the special interphase between rutile and anatase, which not only restrains the recombination of photogenerated electron-hole pairs but also reduces the adsorbability of nanometer anatase TiO2 powder to a certain extent. More significantly, the anticipatory interlaced energy level of heat-treated TiO2 particles is convenient for capturing photons of low energy and thus achieves the intention of using visible light.