Graphene-based nanostructures for enhanced photocatalytic degradation of industrial dyes

Graphene oxide (GO) is an sp²-bonded single atomic layer of carbon atoms with plenty of oxy-functional groups at its surface. The occurrence of large surface area (~ 2630 m²/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 (TiO<inf>2</inf>)-based composites, GO-TiO<inf>2,</inf> and reduced GO-TiO<inf>2</inf> (rGO-TiO<inf>2</inf>). 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%)-TiO<inf>2</inf> composite shows the maximum degradation (~ 95%) of both 10 ppm Eosin Y and MB dyes in the aqueous dispersion. The enhanced photocatalytic activity of rGO-TiO<inf>2</inf> composites as compared to TiO<inf>2</inf> and GO-TiO<inf>2</inf> can be credited to the presence of efficient electron shuttling from the conduction band of TiO<inf>2</inf> into the conductive regions of graphene which eventually restricts further recombination of e⁻/h⁺ pairs. Furthermore, the effects of solution pH and TiO<inf>2</inf> loading are studied on the degradation process.