TiO2@MgAl-layered double hydroxide with enhanced photocatalytic activity towards degradation of gaseous toluene

Abstract

The nanocomposite of TiO2 and MgAl-layered double hydroxide (TiO2@LDH) possessing high photocatalytic activity was synthesized by dispersing TiO2 nanoparticles on the surface of LDHs with a distinct heterojunction. The structure and property of resulted materials were carefully characterized via XRD, SEM, EDS, (HR)TEM, XPS, FT-IR, TGA, BET and UV–vis spectroscopy. Pseudo in situ measurement in ultraviolet and visible domains (Pseudo in situ means that the toluene will be detected in the cuvette during the photodegradation progress) strategy was chosen for the photodegradation of volatile organic compounds. Gaseous toluene as a model pollutant was selected to estimate the photocatalyst efficiency of TiO2@LDH. Results showed that the as-prepared TiO2@LDH nanocomposites have extremely high photocatalytic activity towards the degradation of toluene under simulated sunlight and true sunlight, with a removal rate of 85.9% and 91.7%, respectively. According to the kinetic data, the reaction rate constant of 30 mg TiO2@LDH photocatalyst for the degradation of a toluene solution 171.6 mg m−3 is 0.0100 min−1. The high photocatalytic activity of TiO2@LDH nanocomposite is due to the positive charges on the surface of LDHs and reactive radicals (HO and O2−) generated at the TiO2@LDH interface. Moreover, the TiO2@LDH catalyst exhibits high stability during the toluene degradation even after four continuous cycles.