Composited micropores constructed by amorphous TiO2 and graphene for degrading volatile organic compounds

Abstract The adsorption ability and photoactivity of photocatalysts directly determine the mineralization efficiency of volatile organic compounds. In this study, a 2D–2D microporous structure of amorphous TiO2 nanoparticles and graphene (GR) was constructed to simultaneously enhance the adsorption ability and charge separation efficiency of catalysts. N2 adsorption–desorption, scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction measurements were conducted to investigate the physical properties of the prepared samples. The atmospheric surface photovoltage (SPV) was utilized to study the separation process of the photogenerated charge carriers. Toluene was chosen as the model agent to estimate the adsorption ability and photoactivity of the samples. Results showed that the amorphous TiO2 nanoparticles homogeneously deposited onto the GR surface and hence formed a 2D–2D microporous structure. Although the surface area of the GR–TiO2 compositions increased by only 4–8% relative to that of microporous TiO2 alone, the amount of adsorbed toluene for the GR–TiO2 compositions was 156–193% times higher than that for the microporous TiO2. The SPV result proved that the GR significantly enhanced the intrinsic separation of the photogenerated charge carriers. The contribution of O2 and the GR to the charge separation was dependent on the weight addition ratio of the GR. The GR dominated the charge separation process as its weight addition ratio ≥5%. Given the advantages in adsorption ability and photoactivity, toluene showed mineralization efficiencies for the composite with 5.0 wt% GR of 1.4 and 2.7 folds those of microporous TiO2 and P25, respectively, after 96 min irradiation.