Electrochemical preparation and photocatalytic performance of graphene/nano TiO₂ composites

A stable dispersion in mixed solvent of water and N, N-dimethyl formamide (DMF) of graphene (G) was synthesized by constant voltage one-step electrochemical approach using a high-purity graphite rod as the raw material and mixed acid as the electrolyte. The G/nanoTiO₂ photocatalytic composites were prepared by the method of sol-gel and high temperature heating under nitrogen protection using butyl titanate ester and G as the precursors. The structural properties and microcosmic morphology of the graphite stripping product were characterized by using XRD, FTIR, ultraviolet-visible spectroscopy(UV-Vis), XPS, SEM and TEM. The photocatalytic properties in the anoxic water of different G/nano TiO₂ composites dosages were studied by using 3,5-dinitrosalicylic acid(DNS)as the probe and ultraviolet light as the light source. The results show that distance between layer is enlarged, layers have high transmittance and less reactive groups are generated on six carbon ring and the conjugated π bond structure of G get good maintain by the method of constant voltage one-step electrochemical. The as-prepared G/nano TiO₂ microcosmic morphology shows that well crystallized, closely combined with the TiO₂ is found to be deposited on G. The degradation experiment shows that G/nano TiO₂ composites have good performance for the photocatalytic degradation of DNS, and photocatalytic activity has a direct influence by different dosages. The nitryl become amino in benzene ring, the middle products of 5-aminosalicylic acid or phloroglucinol are produced from the photocatalytic reduction reaction of DNS under the anoxic condition, part of DNS is decomposited and CO₂ and H₂O are generated by photocatalytic oxidation.