Use of the graphite intercalation compound to produce low-defect graphene sheets for the photocatalytic enhancement of graphene/TiO2 composites

Abstract

A series of graphene-TiO2 (GS/TiO2) composites was successfully prepared by the reaction of TiO2 and low-defect graphene obtained from the exfoliation of a blue, stage-1 Na-ethylenediamine-GIC in dimethylsulfoxide. The photocatalytic performance of GS/TiO2 composites was studied by degradation of methylene blue (MB) under UV light in comparison with rGO/TiO2 and Graphite/TiO2. For the structural characterization, both anatase and rutile phases were observed in the GS/TiO2 as indicated by X-ray diffraction (XRD) patterns. The graphene sheets were homogeneously dispersed in TiO2 matrix without the formation of crystalline graphite. According to Raman and X-ray photoelectron spectroscopy (XPS) analyses, the results suggested that low-defect graphene sheets functionalized by amide groups on the edge were presented in GS/TiO2 composite with the ID/IG ratio of 0.30. For the photocatalytic degradation of organic dye MB, GS/60TiO2 provided the highest activity with 92% degradation which was superior to other catalysts, including rGO/TiO2 and Graphite/TiO2. This was attributed to the strong synergistic interaction of low-defect graphene sheets and TiO2. The photochemical stability and reactivity of GS/60TiO2 were also demonstrated after the catalyst was cycled for five times.