One-step vapor diffusion synthesis of uniform CdS quantum dots/reduced graphene oxide composites as efficient visible-light photocatalysts

CdS quantum dots (QDs)/reduced graphene oxide (RGO) composites were synthesized through a one-step vapor diffusion process in the presence of ethylene glycol. The in situ growth of CdS QDs and the reduction of graphene oxide (GO) were completed simultaneously. Fourier transform infrared spectra, X-ray diffraction patterns, X-ray photoelectron spectroscopy and Raman spectroscopy confirmed the reduction of GO. Electron microscopy indicated uniform CdS QDs with size around 4-7 nm were well distributed on the RGO sheets. The transient photocurrent response, electrochemical impedance spectroscopy and diffuse reflectance UV-visible spectra of CdS QDs/RGO composites and CdS were tested to explain the role of RGO for the photocatalytic reaction. As-obtained composites exhibited better photocatalytic properties than pure CdS under visible light irradiation. The influence of different contents of GO on photocatalytic performance was also investigated. A possible photocatalytic mechanism of CdS QDs/RGO composites was proposed.