Research On Synthesis And Photocatalysis Performance Of Titania-graphene Composites

TiO₂ nanoparticles are widely applied in the field of sewage treatment,solar cell and others.However,there are two drawbacks of this material.First,its photocatalytic activity can only be motivated under the ultraviolet light,so that the utilization rate of visible light is low.Second,the high recombination rate of photogenerated electrons and holes lead to the low photocatalytic efficiency.Thus,it’s urgent to synthesize a kind of photocatalyst that have a narrow energy-band width and can suppress the recombination of generated electrons-holes.Graphene is a kind of 2D structure material with one atomic sheet,its unique optical properties made the graphene had a widely application in the photocatalysis.On the basis of previous research,this paper synthesized different structures of TiO₂-graphene composites which can improve its photocatalytic efficiency.First,the N-TiO₂/RGO composites can be prepared by simple hydrothermal synthesis.Using butyl titanate（TBOT）and an aqueous solution of graphene oxide（GO）as raw material,the N-TiO₂ nano-powders can be prepared at 30℃via the sol-gel method,and then the N-TiO₂/graphene（N-TiO₂/RGO）were prepared through hydrothermal at high temperature and pressure.The photocatalytic properties of N-TiO₂/RGO composites can be evaluated by degradation of methyl orange（MO）solution under visible light irradiation simulation.The results demonstrated that its photocatalytic performance had improved significantly with increasing of graphene,the MO dye can be almost completely degraded within 60 min.This photocatalyst can also be used for degradiation on methylene blue（MB）,rhodamine B（Rh B）.In order to reuse the photocatalyst,on the basis of this structure,the Fe₃O₄ particles were loaded on the GO surface by one step hydrothermal method and their photocatalytic properties were explored with the same methods as above.Second,TiO₂/RGO composites were prepared via simple chemical condensation.In the experiment,the homogeneous TiO₂ microspheres can be prepared by a modified sol-gel method with titanium isopropoxide（TPT）as raw material.And then the surface of TiO₂was modified by-NH₂ in order to have a better chemical reaction with-COOH.Consequently,TiO₂ can be transformed into anatase,and the GO can be reduced into reduced graphene oxide（RGO）through hydrothermal.The photocatalytic performance of the composites was evaluated by degradation of MO solution under simulated visible light irradiation.The results showed that the degradation rate of the MO can be reach about 98%within 30 min.Finally,the hollow TiO₂/GO composites of the photocatalyst were prepared.In the experiment,C sphere was used as a template to prepare hollow TiO₂,then the hollow TiO₂/GO composites can be obtained by chemical condensation.In this work,we explored the effects of hydrothermal reaction time and the compound ratio.What’s more,the MO can be degraded completely within 120 min under the light,and it also had a good performance in the degradation of MB and Rh B.This paper has further characterizations for the composites through XRD,SEM,FT-IR and explore the effects of concentration and pH of dyes.