Graphene-based nanostructures for enhanced photocatalytic degradation of industrial dyes

Graphene oxide (GO) is an sp(2)-bonded single atomic layer of carbon atoms with plenty of oxy-functional groups at its surface. The occurrence of large surface area (similar to 2630 m(2)/g), surface functionalities, electronic, and mechanical properties make graphene-based compounds favorable for remediation applications. We report the synthesis and comparative dye degradation efficiencies of two titania (TiO2)-based composites, GO-TiO2, and reduced GO-TiO2 (rGO-TiO2). Both the composites are characterized using SEM-EDX, TEM, FTIR, and XRD. We study the photocatalysis-mediated degradation of anionic dye Eosin Y and cationic dye Methylene blue (MB) in aqueous dispersions under white light and UV irradiation. Our results demonstrate that rGO(10 wt%)-TiO2 composite shows the maximum degradation (similar to 95%) of both 10 ppm Eosin Y and MB dyes in the aqueous dispersion. The enhanced photocatalytic activity of rGO-TiO2 composites as compared to TiO2 and GO-TiO2 can be credited to the presence of efficient electron shuttling from the conduction band of TiO2 into the conductive regions of graphene which eventually restricts further recombination of e(-)/h(+) pairs. Furthermore, the effects of solution pH and TiO2 loading are studied on the degradation process.