Synthesis of ZnO/Graphene Oxide Nanocomposites and its Application in the Photo-removal of Methylene Blue Dye from Aqueous Solution under Ultra Violet Light

It has been found that semiconductor nanocomposites have good photocatalytic behavior and can be used for the photodegradation of organic pollutants in water waste. ZnO, one of the eco-friendly semiconductor materials, was chosen to form a nanocomposite with graphene oxide. Graphene oxide in ZnO-based nanocomposites improves the photoactivity and photostability of ZnO. To prepare the graphene oxide, the Hummers method was used, then ZnO/GO nanocomposite was synthesized by hydrothermal method. The nanocomposites were annealed at different temperatures of 300 °C, 400 °C, and 500 °C. Raman spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR) confirmed the structure of synthesized graphene oxide nanosheets. Structural characterization of the nanocomposites was investigated using X-ray diffraction, Transmission Electron Microscope (TEM), and Field Emission Scanning Electron Microscope (FE-SEM). X-ray diffraction patterns of nanocomposites demonstrate that the annealed sample at 300 °C has better crystallinity than the other samples and was used to investigate the photocatalytic process. Photocatalytic experiment of the ZnO/GO was carried out by degradation of methylene blue using a laboratory-made reactor in alkaline, acidic, and neutral solutions. Photodegradation results were revealed that the maximum percent degradation of 87% was achieved in the alkaline solution.