Contributions of Surface Oxygen Species and Photoinduced Holes on Photothermocatalytic Toluene Oxidation over CeO2–MgO

To reveal the activity enhancement mechanism of volatile organic compounds (VOC) oxidation reaction, is vital for developing high-efficiency and cost-effective photothermocatalytic materials. Herein, porous and low-cost CeO2–MgO composite oxides were simply constructed via the solution combustion method and applied for toluene photothermocatalytic oxidation. The conversion rate for 1500 ppm of toluene over the optimized sample could reach 90% under the photothermocatalytic process at 330 °C and a gas hourly space velocity of 60,000 mL·g–1·h–1. Both gas phase oxygen and reactive oxygen species (ROS) played the dominant role in the photothermocatalytic activity while the total contribution rate of photoinduced holes and surface lattice oxygen was 25% to the activity. In situ Fourier transform infrared and electron paramagnetic resonance results revealed that the synergistic photothermo activation of molecular oxygen accelerated the low-temperature ROS formation. Under irradiation, photoinduced electrons could benefit the efficient transfer from superoxide radicals to peroxide radicals on material. Hence, it provides not only a comprehensive understanding on the activity enhancement mechanism at the molecular level but also a theoretical reference for designing objective catalysts for VOC abatement.