Preparation of TiO2/graphene-based composites and photocatalytic degradation of dyes
Reduced graphene oxide(rGO)and a series of rGO/TiO2 nanocomposites with different concentra-tions(0,5％,10％,15％,and 20 wt％)were prepared by the modified Hummers'method for the preparation of graphene oxide(GO)and TiO2 by hydrolysis and solvent-thermal method.The synthesized products were characterized by SEM,XRD,XPS,DRS,Raman,etc.,to investigate the degradation effect of pure TiO2 and rGO/TiO2 composite catalysts on methylene blue dye(MB)under different experimental conditions.The re-sults showed that the TiO2 in the composite photocatalyst was mainly in anatase phase,and the reduced gra-phene oxide(rGO)introduced by solvothermal synthesis had no effect on the physical phase of TiO2.The intro-duction of rGO made the absorption band of rGO/TiO2 red-shifted to a certain extent,and the width of the TiO2 forbidden band was reduced from 3.23 to 3.09 eV.The synthesized(15 wt％)rGO/TiO2 has the best pho-tocatalytic effect and the highest photocatalytic activity,and the degradation rate of 20 mg/L methylene blue dye under 100 W high-pressure mercury lamp irradiation for 70 min reaches 97.6％,and the degradation rate of 20 mg/L methylene blue dye under 500 W xenon lamp irradiation for 70 min reaches 93.2％.The composite photocatalysts of(15 wt％)rGO/TiO2 have the good photocatalytic degradation and cyclic stability.rGO/TiO2 had a degradation efficiency of 86.1％after 5 cycles of photocatalytic degradation.The rGO/TiO2 composite photocatalyst show excellent adsorption and photocatalytic performance,which can provide an effective method for the photocatalytic treatment of waste liquids.
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