Facile synthesis of ZnO/GO nanoflowers over Si substrate for improved photocatalytic decolorization of MB dye and industrial wastewater under solar irradiation

In this work, we report a new method for the synthesis of zinc oxide (ZnO) nanoflowers/graphene oxide (GO) composite, uniformly grown over Silicon (Si) substrate. The synthesis is performed by utilizing aqueous chemical approach where ZnO nanoseeds are obtained using zinc acetate (C4H6O4Zn) and isopropanol (C3H7OH), while Graphene oxide (GO) is fabricated by using Hummer's method. The nanocomposite was fabricated by mixing of GO and ZnO nanoseed solution followed by vigorous ultra-sonication and spin-coating over the Si substrate. Finally, the nanoflowers type structures were grown from ZnO nanoseed by placing the coated Si substrate in a solution containing Zn+2 environment. The nanocomposite was characterized by various techniques such as Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray diffraction (XRD) analysis. The performance of nanocomposite was analyzed for remediation of methylene blue (MB) dye by utilizing sunlight as an energy source to initiate the photoreaction. The composite (GO/ZnO) shows similar to 33% faster decolorization of 20 mg/L of MB dye in comparison with pure ZnO. The improved performance is attributed to the prevention of recombining of electron (conduction band) and holes (valence band) during the photocatalytic reaction. Moreover, GO itself provides excess electrons for enhancing the photocatalytic reaction by providing excess hydroxyl radicals. Further, the nanocomposite was successfully utilized for decolorization of an industrial dye. Hence, nanoflowers type ZnO/GO composite material grown over Si substrate provides an alternative for effective removal of real dye from industrial wastewater without any post process filtration requirement.