The Preparation And Visible Light Photocatalystic Property Of Titania Nanosheet-graphene Hybrid Photocatalyst

Two-dimensional(2D)nanosheets display excellent physical and chemical properties and attracted intense research attentions.In this dissertation,titania nanosheet,graphene and cation polyelectrolyte(PDDA)are used to prepare hybrid photocatalyst by the electrostatic flocculation and high temperature calcination.The preparation conditions are optimized.The hybrids photocatalysts show remarkable photocatalytic activities upon irradiated by visible light,which are not presented by its corresponding compeontents(titania nanosheet,graphene,PDDA)by themselves.The efficiency of hybrid photocatalyst under visible light is nine times that of the efficiency of titania nanosheet under UV light.We expect that this study will provide perspective in the preparation of visible-light activated photocatalytic materials.In the dissertation,the preparation of titania nanosheet was firstly studied.Layered titanate crystal is fabricated by high temperature solid-state calcination method,and then titania nanosheet is obtained by ion exchange and exfoliation of the layered materials.A detailed analysis of titania nanosheet concerning its morphology thickness distribution has been characterized by SEM,TEM,AFM.The hybrid photocatalyst is successfully synthesized by using electrostatic interactions between titania nanosheet,graphene and the positive charge PDDA followed by high temperature calcination.By employing XRD,SEM,EDS,FT-IR,Raman,TGA,the morphologies and structure of hybrid photocatalysts have been analyzed in detail.The hybrid catalyst is micro-nano particles with porous surfaces.The elements of C,N,O dispersed homogeneously on the surface of the hybrid photocatalysts.The content of graphene is important to the morphologies of photocatalysts.The light abstraction range of the hybrid photocatalysts extended to visible light region.Finally,the degradation effect of methylene blue has been studied using hybrid photocatalyst under visible light.It shows that the hybrid photocatalyst has superior visible-light activated photocatalyst.The fraction of grapheme oxide influenced the performance of the catalyst.Under visible light,the efficiency on the degradation of methylene blue is optimal when the fraction of graphene during the preparation step is 5%.The different calcination temperature has significant influence on the photocatalytic activities.At 300℃ or 400℃,the photocatalytic activity of MB degradation is the best.In the dissertation,the reason of the emergence of the visible-light photocatalytic activity of the catalyst is explored.