Fabrication of sandwich-structured ZnO/reduced graphite oxide composite and its photocatalytic properties

ZnO/RGO (ZnO/Reduced Graphite Oxide) composites with sandwich structure (layered structure) were synthesized at relatively low temperature (60 °C) using ZnSO₄ and GO (Graphite Oxide) as precursors. Compared with pure ZnO, ZnO/RGO composites showed greatly enhanced-UV photocatalytic activity for the degradation of the organic dye methyl orange (MO). The structure and morphology of as-prepared samples have been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FE-SEM), etc. ZnO/RGO composites had a sandwich structure, which would be enhanced when exfoliated GO was used. During the formation the composites, GO was reduced to RGO (graphite-like carbon named as Reduced Graphite Oxide, RGO). The groups which exist in GO (such as C=O, C–O–C) disappeared or obviously weakened, while the groups similar to those in graphite (such as C=C) appeared at the same time. Photoluminescence (PL) spectra of ZnO/RGO showed a significant decline compared to that of pure ZnO, which suggests that the recombination of excited electron–hole pair (e⁻–h⁺) may be efficiently inhibited by the transfer of electrons to the carbon neighbor. The enhanced-photocatalytic activity for ZnO/RGO can be attributed to the migration effect of photoinduced electrons on the interface of RGO and ZnO. The photocorrosion effect of ZnO was found to be evidently suppressed according to Inductively Coupled Plasma Optical Emission Spectrometry (ICP).