Interface of GO with SnO2 quantum dots as an efficient visible-light photocatalyst

Graphene oxide (GO) with beneficial functional groups regulates the surface chemistry for catalytic applications. However, the low electrical conductivity of GO invokes further treatments that compromise the above-valued properties. We report an interfacial engineering of GO decorated with SnO2 quantum dots (QDs) for the visible-light-driven catalysis of dye degradation. Retention of beneficial functional features of GO and QDs in the GO-SnO2 composite is established by using TEM, FTIR, and Raman spectroscopy techniques. Further, investigations with EXAFS and lifetime-measurements provide the local structure and defects distributions in QDs which are correlated with the improved conductivity. PL and electrochemical impedance spectroscopic measurements help unraveling the charge-transfer across the interface of the GO-SnO2 composite. The unique ability of ∼94% degradation of MB using only 0.5 mg of GO-SnO2 catalyst within half an hour under the visible light is demonstrated for the first time with insights on the photocatalytic mechanism. [Display omitted] •Defect laden SnO2 QDs is interfaced with GO and the composite is examined using XRD, Raman and TEM.•Defect from SnO2 improved the conductivity in GO-SnO2 is verified using EIS and well supported by EXAFS.•Presence of functional groups in the GO helps for better dispersion and adsorption of dye is reinforced by FTIR.•Better charge transfer from QD to GO due to work function mismatch, suggested by PL spectra.•Visible-light-driven degradation of MB within 30 min is registered using 0.05 mg/ml of the composite.