Study On Fabrication And Visble Light Photocatalysis Properties Of Graphene/TiO₂ Composites

Titannium dioxide is very important semiconductor photocatalysts with high photocatalytic activity, good chemical stability, low cost. However, Ti O2 has wide band gap, it only can use ultraviolet light, which lead to low efficiency of sunlight. To solve this problems, In this paper graphene composite with Ti O2 to improve the visible light catalytic activity of Ti O2 catalyst. Graphene/Ti O2 nanocomposites have prepared by the alcohol-thermal method and electrospinning technique. This paper has studied the preparation of different graphene/Ti O2 nanocomposites and visible photocatalytic properties.In this paper, graphene was prepared by using natural flake graphite as raw material. Using improved Hummers method, the natural flake graphite was oxidized for layered structure of graphite oxide, then graphene was prepared by using thermal reduction method. The structure and morphology of graphene was studied by Raman spectra, AFM and SEM.Using alcohol-thermal method and electrospinning technique, this paper prepared for graphene-Ti O2 composite powders、graphene-Ti O2 composite fibers、Ti O2-graphene-PVP composites 、 Ti O2-graphene/Ti O2 composites. The structures, morphology and optical properties were characterized by XRD、FT-IR、Raman spectrum、SEM、UV-Vis absorption spectrum. UV-Vis absorption spectrum results demonstrated that the light absorption of composites can be extended to visible light region by doping graphene. The band gap of graphene-Ti O2 composite powders and Ti O2-graphene/Ti O2 composites calculated from UV-Vis absorption spectrum are 2.89 e V、2.48 e V respectively, which suggested that the band gap of composites can be effectively reduced by doping graphene.Using methylene blue as organic pollutant and above prepared graphene/Ti O2 composites as photocatalyst, visible photocatalytic degradation experiments were carried out under the same conditions. After 180 minutes, the degradation efficiency of methylene blue by P25、graphene-Ti O2 composite powders、Ti O2-graphene-PVP composites 、 Ti O2-graphene/Ti O2 composites were 19%, 74%, 97%, 97.7% respectively. And the photocatalytic reaction rate constant were 0.00123/min, 0.0154/min, 0.0167/min, 0.0186/min. This showed that the visible photocatalytic activity of composites was enhanced greatly by doping graphene.