Efficient photocatalytic degradation of gaseous toluene over F-doped TiO2/exfoliated bentonite

To solve the aggregation problem of TiO 2 nanomaterials and improve the catalytic efficiency, F-doped TiO 2 /exfoliated bentonite (TF/EB) composite was prepared by dispersing F-doped TiO 2 (TF) nanoparticles on an exfoliated bentonite (EB) using a facile sol–gel method. The exfoliated bentonite was prepared by liquid-exfoliation method from the natural bentonite (B). The prepared samples were applied for toluene degradation in gas phase under UV and visible light irradiation. The as-prepared TF/EB composite exhibited higher toluene degradation efficiency than that of pure TiO 2 , F-doped TiO 2 and TF/B composite. Results indicated that the calcination temperature and the initial F/Ti atom ratio of reaction precursors greatly affected the photocatalytic activity towards toluene degradation. The best photocatalytic performance was obtained by the sample calcinated at 400 °C with an initial F/Ti atom ratio of 5%. The improved photocatalytic performance is ascribed to a series of benefits introduced by F-doping and exfoliation process. The presence of F - ions increases the percentage of exposed   reactive {0   0   1} facets on TiO 2 . Moreover, F - ions incorporated into the TiO 2 lattice generate oxygen vacancies and Ti 3+ defects, which influence the transfer and migration of the photoinduced charge carriers and induce a visible-light photocatalytic activity . Furthermore, the electrostatic interaction of negatively charged exfoliated bentonite surface leads to a more efficient separation of charge carriers.