The 3D String And Ball-like TiO₂/rGO Composites With High Photo-catalysis Degradation Capability For Cationic Dyes

A TiO₂-graphene composites with three-dimensional string ball-like structure（STG）were prepared by low temperature hydrothermal treatment.The synthesis method is simple,green,and low energy consumption.The photo-catalytic degrading Methylene blue（MB）,Methyl orange（MO）and Rhodamine B（RhB）under ultraviolet light by the STG composites were investigated.Firstly,the GO was prepared by the modified Hummers method.What’s more,the string ball-like structure TiO₂（ST）was originated from hydrolysis of TiCl₄ by mechanical agitation.Then,the mixture mixing the GO aqueous solution with ST was treated by low temperature hydrothermal process to obtain the STG composites.The ST,STG composites were analyzed through a series of characterization i SEM,TEM,XRD,BET,FTIR,XPS,Raman,UV-vis DRS,PL and EIS.XRD results confirmed the phase of TiO₂.The SEM and TEM outcomes showed that the successful combination between TiO₂ and rGO.The specific surface area of STG-1.0 wt%composites is 142 m²/g which higher than pure TiO₂.The FTIR,XPS and Raman characterizations demonstrated that the GO was reduced after hydrothermal treatment in some degree and the graphene contacted with TiO₂ through Ti-O-C bond.From zeta potential distribution of STG composites and ST,the zero potential of STG composites was 6.2 while the ST was 4.0.The zero potential higher,the stronger adsorption ability of material.What’s more,the UV-vis DRS pattern displayed that the STG composites have red shift phenomenon compared with pure ST.PL and EIS results showed the excellent conductive characteristic of GO making the STG composites have low combination rate of photo-generated electrons-holes pairs,which can improve the photo-catalytic ability of the STG composites.The STG-X（X=0.1⁹.0 wt%,rGO weight ratio）composites were applied to degrade three typical cationic dyes,including MB,MO and Rh B under UV light condition.Firstly,the adsorption data of MB were analyzed and fitted by STG composites.It was found that the adsorption behavior of MB belonged to Langmuir adsorption model,and the adsorption rate was fast and the process could reach equilibrium in 20 min.In the photocatalytic experiment,STG-1.0 wt%composites exhibited the best photocatalytic activity,and the removal rate of MB was 87.2%（10ppm）,50%（20 ppm）,and the removal rate of 10ppm MO,Rh B was over 99.0%.Finally,the effects of different kinds of high active radicals on the photocatalytic degradation of MB were explored.The synergistic effect of adsorption and photocatalysis of rGO and ST on the photocatalytic activity of STG composites was determined.In this paper,three-dimensional structure of string TiO₂/rGO composites were prepared by a low energy consumption,simple and easy to operate low-temperature hydrolysis hydrothermal method and the synthesis and application of materials to the dyestuff waste-water problem provides a new basic research technology reserves and broad vision for us.