| A series of fluorinated anatase TiO2 nanosheets with dominant(001) facets were synthesized to oxidize and reduce waste water containing p-chlorophenol(PCP) and Cr(VI) simultaneously under visible light. The(001):(101) surface facets ratio of TiO2 was controlled by varying the initial HF concentration, and fluorine-free samples were obtained by alkaline-washing. In the simultaneous ternary system, the PCP and Cr(VI) removal increased markedly under the same operating conditions.The structure and properties of the resultant catalyst powders were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Electron paramagnetic resonance spectroscopy, Field-emission scanning electron microscopy, Transmission electron microscopy, and Brunauer– Emmett–Teller analyses. A synergistic effect among TiO2, Cr(VI), and PCP was observed in the simultaneous ternary system, which is ascribed to effective trapping of photogenerated electrons and holes by Cr(VI) and PCP, respectively. Furthermore, an optimum molar ratio of concentration of PCP to Cr(VI) based on the maximum synergistic effect was determined. The maximum synergistic effect was obtained at a molar ratio of [PCP] to [Cr(VI)] of 1. Moreover the optimum ratio of exposed(001) to(101) facets for Ti O2 was determined to be 80:20 because of selective transfer and charge balance of photogenerated carriers. Surface fluorination facilitates the formation of oxygen vacancies and unsaturated Ti atoms, which is useful for visible light activity induction, for extending the life time of photogenerated electron-hole pairs, and for enhancing the rate of PCP oxidation and Cr(VI) reduction. |
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