Synthesis of TiO2/GO composite film via an electrochemical route

A nano-structured film composed of TiO2 and reduced graphite oxide (GO) was synthesized on ITO glass via a typical electrochemical route. A mixed solvent of Ti(SO4)2 and GO was prepared, with the addition of H2O2, HNO3 and DMF at different ratio. A setup of two electrodes of ITO glass in a plastic cell and an electrochemical analyzer is used for the film forming. The film is characterized with a microstructure of GO plates being perpendicular to the glass substrate, since GO in the electrolyte solvent is separated as small plates at about several nanometers in diameter. TiO2 is found being deposited between these GO plates. This microstructure is quite different from the film formed by normal deposition, where the GO plates are generally parallel to the substrate. The oxygen containing groups of C=O, C-O-C and C-OH on the GO surface are reduced because of neighboring to TiO2, it means two phases being bonded to each other at the interface. The photoelectric current of the composite film is compared with the pure TiO2 film, the former one is almost one time higher than the latter one. The degradation of methyl orange of two kinds of film is also analyzed under the irradiation of ultraviolet light. The photocatalytic activity of two kinds of film presents the same trend of variation as that of photoelectric current. These results suggest that the photoexcited electrons of TiO2 may quickly transfer to the glass substrate through the reduced GO neighbor, that owns a better conductivity, and so far decrease the recovery of excited electron-hole. The unordinary microstructure of the composite film may favor both to the electron transmission between the GO and ITO glass substrate, and to the light excitation of TiO2. The microstructure of different films was studies by AFM, XPS, FESEM. The photo-electrochemical property was measured by an electrochemical instrument Model CHI660C with Blupoint4 as a UV light source.