Solvothermal synthesis of graphene–CdS nanocomposites for highly efficient visible-light photocatalyst

Graphene–CdS (G/CdS) nanocomposites were successfully synthesized via a facile and efficient solvothermal route. The structure and composition of the obtained nanocomposites were studied by means of X-ray diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectra (XPS), and UV–Vis spectrophotometry. XRD result showed that the CdS nanorods crystallized in a hexagonal structure. SEM and TEM observations demonstrated that a homogeneous distribution of CdS nanorods on the graphene nanosheets (GNS) was formed. FTIR and XPS analyses indicated that graphite oxide (GO) has been simultaneously reduced to GNS during the deposition of CdS nanocomposite. Furthermore, visible photocatalytic activity of the composite was tested using Rhodamine B (Rh. B) as the model contaminant. Compared with the bare GNS and CdS nanorods, the G/CdS nanocomposite displayed distinctly enhanced photocatalytic activities.

Graphical abstractIn the system, because there were many functional groups such as epoxy groups (C–O–C), hydroxyl groups (–OH), carbonyl groups (CO) and carboxylic acid groups (–COOH) on the surface of GO, Cd2+ could be tightly adsorbed onto the GO surface via the electrostatic interaction. In the followed process, the hydrolysis/dissociation reactions of CH4N2S in EDA solution would generate sulfur ions and cause the nucleation of CdS. The reactions proceed faster at a higher temperature and facilitate the nucleation. At the same period, the starting GO sheets were reduced to GNS due to the solvothermal treatment in EDA solution and promoted the formation of G/CdS composites ultimately during the hydrothermal period.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Graphene–CdS nanocomposites were synthesized via a facile and efficient solvothermal route. ► A homogeneous distribution of CdS nanorods were coated on graphene sheets effectively. ► The graphene–CdS nanocomposites displayed distinctly enhanced photocatalytic activities.