Preparation Of Co₃O₄/TiO₂ Nanocomposites And Study On Catalytic Purification Of VOC

Nowadays,air pollution contains many kinds of pollutants,among which VOCs can cause serious damage to animals,plants,human beings and other objects.Therefore,it is an important task recognized by the government and the people to adopt effective methods to control the pollution of volatile organic compounds.At present,there are some problems in catalysis,such as low photocatalytic efficiency and high energy consumption of thermocatalytic.It is urgent to improve the utilization of photocatalysts and reduce the energy consumption of thermocatalytic.Co₃O₄ and TiO₂ are used as traditional photocatalysts and good thermal catalysts respectively.It is of great significance to find a way to improve the catalytic effect of titanium dioxide and cobalt tetroxide.A sample of Co₃O₄ mesoporous nanorods?Co₃O₄-MNR?with a considerable number of Co²⁺vacancy defects was prepared by hydrothermal method.Co₃O₄-MNR samples exhibits highly effective photothermocatalytic activity and excellent durability for the gas-phase oxidation of benzene?a recalcitrant poisonous air pollutant?under UV-visible-infrared illumination from a Xe lamp.Compared to a commercial Co₃O₄sample?Aladdin?with a smaller number of Co₂₊vacancies and TiO₂?P25?,the CO₂production rate of Co₃O₄-MNR has been greatly increased.Charaterization by BET,XRD and ICP,together with the experimental evidence of isotope labeling,CO-TPR,and FTIR with the DFT calculations,And we found for the first time that presence of Co²⁺vacancies in Co₃O₄-MNR significantly increases the thermocatalytic activity of Co₃O₄;we also found a novel photoactivation on Co₃O₄,quite different from the conventional photocatalysis of semiconductor photocatalysts such as TiO₂:the illumination from the Xe lamp enhances the activity of the lattice oxygen in Co₃O₄-MNR,thus considerably promoting the solar-light-driven thermocatalytic activity of Co₃O₄-MNR.Co₃O₄/TiO₂ nanocomposites with different Co/Ti molar ratios?0.1,0.2,0.3,0.4?were prepared by hydrothermal method.Compared to pure TiO₂,the samples exhibit highly effective photothermocatalytic activity and excellent durability for the gas-phase oxidation of benzene and the Co₃O₄/TiO₂ nanocomposite with the optimum Co/Ti molar ratio of 0.30 exhibitde the best photothermocatalytic activity and better durability with ultraviolet-visible-infrared?UV-vis-IR?irradiation.They also exhibit effective catalytic activity for benzene abatement even with IR irradiation.After XRD,XPS,TEM,TPR and TPO characterized tests,we found a novel synergetic effect among light-driven thermocatalysis on Co₃O₄ and UV photocatalysis on TiO₂;At the same time,A novel photoactivation,completely different from photocatalysis on TiO₂,is discovered to further considerably accelerate light-driven thermocatalytic activity of Co₃O₄:Irradiation not only promotes the activity of lattice oxygen of nano Co₃O₄ but also accelerates the reoxidation of the reduced cobalt oxide(Co₃O_4-x),resulting in a considerable enhancement in the light-driven thermocatalytic activity of Co₃O₄.