Synergetic Effect between Photocatalysis on TiO₂ and Thermocatalysis on CeO₂ for Gas-Phase Oxidation of Benzene on TiO₂/CeO₂ Nanocomposites

Abstract

TiO₂/CeO₂ nanocomposites of anatase TiO₂ nanoparticles supported on microsized mesoporous CeO₂ were prepared and characterized by SEM, TEM, BET, XRD, Raman, XPS, and diffuse reflectance UV–vis absorption. The formation of the TiO₂/CeO₂ nanocomposites considerably enhances their catalytic activity for the gas-phase oxidation of benzene, one of the hazardous volatile organic compounds (VOCs), under the irradiation of a Xe lamp compared to pure CeO₂ and TiO₂. A solar-light-driven thermocatalysis on CeO₂ is found for the TiO₂/CeO₂ nanocomposites. There is a synergetic effect between the photocatalysis on TiO₂ and the thermocatalysis on CeO₂ for the TiO₂/CeO₂ nanocomposites, which significantly increases their catalytic activity. The CO₂ formation rate (<i>r</i>_CO2) of the TiO₂/CeO₂ nanocomposite with the Ti/Ce molar ratio of 0.108 under the synergetic photothermocatalytic condition is 36.4 times higher than its <i>r</i>_CO₂ under the conventional photocatalytic condition at near room temperature. CO temperature-programmed reduction (CO-TPR) with the irradiation of the Xe lamp and in the dark reveals that the synergetic effect, which occurs at the interface of the TiO₂/CeO₂ nanocomposite, is due to the considerable promotion of the CeO₂ reduction by the photocatalysis on TiO₂