Experimental and computational studies of sonochemical assisted anchoring of carbon quantum dots on reduced graphene oxide sheets towards the photocatalytic activity

Highlights: • Sonochemical assisted method was adopted for developing CQDs/rGO catalyst. • DFT calculations showed the decrease in work function of CQDs/rGO nanocomposite. • CQDs/rGO exhibited enhanced photocatalytic activity than that of CQDs and rGO. • The synergetic effects of individual components make CQDs/rGO as efficient catalyst. Herein, carbon quantum dots (CQDs) are anchored on reduced graphene oxide (rGO) sheets by sonochemical assisted method. The developed carbon quantum dots/reduced graphene oxide (CQDs/rGO) catalyst shows enhancement in the photocatalytic degradation of methylene blue and methyl orange under visible light compared to that of individual CQDs and rGO components. The improved performance of the CQDs/rGO catalyst has been attributed to efficient separation of photogenerated charge carriers as studied by photoluminescence studies and to increase in the surface area as studied by Brunauer-Emmett-Teller method. The photocatalytic degradation is studied in detail by varying catalyst loading, dye concentration and the rate constant is determined by first order kinetics. The enhancement in photocatalytic activity of CQDs/rGO catalyst is validated by first principles density functional theory (DFT) calculations which shows the enrichment in density of states thereby decreasing the work function.