Synthesis And Photocataiytic Performance Of TiO₂-graphene Nanocomposite

It is a great challenge to improve the photocatalytic efficiency of the photocatalystand reduce its costs so that this photocatalyst can be more widely used. As aninexpensive and environmentally benign material, TiO2has been extensivelyinvestigated and widely used as a photocatalyst to decompose organic contaminantsfor drinking water and indoor air purification. However, the photocatalytic efficiencyof TiO2is limited by its wide band gap energy (3.2eV for anatase phase and3.0eV forrutile phase), which is only sensitive to the UV light. On the other hand, under solarlight irradiation, electron hole pairs (excitons) can be generated in TiO2, but the rapidrecombination of the photogenerated excitons becomes another factor limiting theefficiency of TiO2. Therefore, narrowing the band gap and prolonging the exciton lifeare the most challenge in the photo-catalytic utilization of TiO2though multiplestrategies have been developed such as compositing TiO2with noble metals, metaloxides and carbonaceous materials.Since the graphene was discovered in2004, this new2D structure carbonnanomaterial is widely used due to its excellent properties. Graphene has excellentelectrical conductivity, which is a good electron acceptor. While graphene has a largespecific surface area, which makes it has a strong adsorption capacity. The uniquetwo-dimensional structure and excellent mechanical properties show its potential to bean excellent support. Based on the above, bringing the graphene into photocatalysismaybe could make up the lack of titanium dioxide.Now there are a series of reports on the titanium dioxide/graphene composites toimprove its photocatalytic efficiency. Currently, there is still much space to improvethe preparation of this composite. First, the preparation of TiO2/graphene compositematerial is complicated and lengthy, which could bring in more by-products.Thetitanium source is not only expensive but also susceptible to hydrolysis, which means that it is difficult to preserve for a long time. On the other side, although thephotocatalytic activity of TiO2/Graphene composite has been improved, it is still faraway from satisfactory. It still could be improved more.Considering the above research background and thinking, this paper mainly focuseson the synthesis and photocatalytic performance of TiO2/Graphene composite. Themajor contents and consequence of this thesis are summarized as following:1. A green, simple and quick hydrothermal synthetic route to produce TiO2nanoparticle/Graphene composites. This method of preparation of TiO2nanoparticle/Graphene composite is simple, environmental friendly. In thepreparation process, this method doesn’t introduce any poisonous, corrosivesubstances, it couldn’t produce any harm by-product to the environment, whichis very green friendly. At the same time, the course of reaction become mucheasier and the reaction time is shorter.2. By controlling the concentration of reactants, reaction time, and reactiontemperature of the experimental parameter, we discuss the influence ofphotocatalytic efficiency of TiO2nanoparticle/Graphene composite with thechange of experimental parameter. Eventually, with the content of GO in TiO2nanoparticle/Graphene composite increases, the photocatalytic activity of TiO2nanoparticle/Graphene composite also increases. When the reaction temperatureis120℃, the reaction time is6h, the GO proportion is44%, we could get TiO2nanoparticle/Graphene composite with the highest photocatalytic activity,which is more activity than P25increased by more than70%.3. A simple hrdrothermal method to produce TiO2nanowire/Graphene composite.This paper uses a two-step hydrothermal synthesis of TiO2nanoparticle/Graphene composite composites. This material forms a porousthree-dimensional structure as a result of the improvement of the photocatalyticactivity of TiO2nanowire/Graphene composite, which is more effective thanTiO2nanoparticle/Graphene composite. With the growth of GO proportion, the photocatalytic activity of the TiO2nanowire/Graphene composite is alsoconstantly improving.