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

Abstract

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.