Graphene oxide capturing surface-fluorinated TiO2 nanosheets for advanced photocatalysis and the reveal of synergism reinforce mechanism

Surface-fluorinated TiO2 (F-TiO2) nanosheets with exposed (001) facets were synthesized from a scalable hydrothermal treatment assisted by a specific stabilization effect of fluorine ions on the (001) facets. Assembly of F-TiO2 on graphene oxide (GO) sheets into GO/F-TiO2 hybrid in aqueous solution was further achieved by making use of the surfactant role of GO. Photocatalytic properties of GO/F-TiO2 hybrid were evaluated under 365 nm UV light irradiation for photodegradation of methylene blue (MB). An optimal GO content has been determined to be 3 wt%, and the corresponding apparent pseudo-first-order rate constant K-app is 0.0493 min(-1), 3 times and 4 times more than that of pure TiO2 nanosheets and commercial P25 photocatalyst, respectively. To reveal the synergism reinforce mechanism of GO/F-TiO2 hybrid, photo absorption, surface absorption, and the photoelectrochemical current properties have been intensively studied. We found that enhanced electron-hole separation has been the key issue for the reinforcement of photocatalytic performance. F-TiO2 with exposed (001) facet has stronger electron-hole separation resulting in a higher photoelectrochemical current than that of P25 photocatalyst. Moreover, hybridization of F-TiO2 with GO could further increase the photoelectrochemical current and the largest current for the optimal weight fraction of GO is in good accordance with the photocatalysis performance. The GO/F-TiO2 interface junction that favors the electron-hole separation was attributed to the photoelectrochemical current enhancement.