Degradation of methylene blue using ZnSe-graphene nanocomposites under visible-light irradiation

In this study, graphene oxide (GO) sheets were synthesized by using a modified Hummers method and Offeman's method. The GO was mixed with ZnSe prepared using various amounts of N2H4 at a ratio of 1:1 to form precursors. The ZnSe/graphene nanocomposites were synthesized under hydrothermal conditions (180 degrees C; 12 h) from the previous precursor. The obtained ZnSe/graphene photocatalysts were characterized by UV vis spectroscopy, transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, X-ray diffraction analysis (XRD), Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). Photocatalytic activity under visible-light irradiation was evaluated in a methylene blue (MB) dye degradation reaction in the aqueous phase. The results show that the ZnSe-N2H4 reacted with the GO, possibly because the N2H4 contained in the ZnSe reduced the GO to graphene and formed a ZnSe/graphene nanocomposite. The GN-5-mL ZnSe nanocomposite prepared in this study could degrade more than 90% of the MB in 2 h and almost completely degrade the MB in 4 h under visible-light irradiation. The degradation efficiency of the ZnSe/graphene nanocomposite was 99.6% after 6 h of visible light irradiation; the pseudo-first-order reaction rate constant of the ZnSe/graphene nanocomposite was 1.27 h(-1). (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.