Preparation And Photocatalytic Properties Of Graphene/Titanium Dioxide Composites

The problem of water pollution treatment has attracted wide attention all around the world.One of the main sources of water pollution is industrial textile dyes.Photocatalytic technology is an effective method to degrade toxic pollutants.However,the representative of traditional semiconductor catalyst TiO2 has the limitations of low utilization rate of visible light and the photo-generated electronic-holes are unstable as well as easy to recombine,which severely affect its applications in life and production.Graphene,which is a novel and special carbonaceous material,has honeycomb structure.The agglomeration of Ti O2 nanoparticles can be dispersed and inhibited when combined with graphene.Besides,it has good conductivity and strong adsorption ability.This paper has contributed to study graphene/titanium dioxide composites,aiming to improve the photocatalytic performance of TiO2? The experimental contents are as follows:In this article,Hummers' method was used to prepare graphene oxide.Then,P25,titanate nanofiber,and titanium sulfate were used as the titanium source respectively to prepare RGO/ TiO2 binary composites by hydrothermal method;the prepared composites were characterized by X-Ray Diffraction(XRD),Scanning Electron Microscope(SEM).Methylene blue was used to simulate organic waste water to observe the effects of different graphene contents,hydrothermal time and hydrothermal temperature on the photocatalytic performance.Results showed that the prepared binary composites with different titanium sources showed enhanced photocatalytic activity under UV light,and the composites using titanium sulfate as titanium source had the best catalytic performance.When hydrothermal time was 12 h,hydrothermal temperature was 180 oC and the content of graphene was up to 10%,photocatalytic activity of binary composite was the best.The degradation rate was about 99.7% under visible light,86.1% under visible light.In addition,N-F-RGO/TiO2 were prepared by hydrothermal method and AgI-RGO/TiO2 ternary composites were prepared by deposition-precipitation method on the basis of binary materials.The prepared composites were characterized by means of X-Ray Diffraction(XRD),Scanning Electron Microscope(SEM),Fourier Transform Infrared Spectrum(FT-IR)etc.The optical response properties were further investigated by UV-vis DRS.Methylene blue was used as the target pollutant to observe the photocatalytic properties under visible light.Results showed that the photocatalysis of N-F-RGO/TiO2 was slightly improved compared with RGO/TiO2 and the degradation rate reached 87.6% under visible light;As for AgI-RGO/TiO2 ternary composite,when n(AgI): n(Ti)= 0.05:1,the addition of it was 1 g/L,the initial concentration of methylene blue was 10 mg/L,pH=9 and reaction time was 210 min,the degradation rate of methylene blue reached 93.6%.The photocatalytic degradation of methylene blue by AgI-RGO/TiO2 composites was in accordance with pseudo-first-order kinetics model.