The synthesis and properties of ZnO–graphene nano hybrid for photodegradation of organic pollutant in water

The nano-sized zinc oxide–graphene oxide (ZnO–GO) hybrid has been prepared by using GO dispersed in the ethanol as carrier, zinc acetate dihydrate and lithium hydroxide monohydrate as reactant. Then the nano-sized hybrid material of ZnO–graphene (ZnO–G) is obtained by thermally treating ZnO–GO at different temperatures. The samples are characterized by using scanning and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman, electron absorption and photoluminescence emission spectroscopy. The results reveal that both sides of the graphene sheets are coated with ZnO particles, and that the lattice constants and the band gap energy of ZnO have been changed compared with the pure nano-sized ZnO particles. The photodegradation of methylene blue (MB) has been investigated in the presence of hybrid materials. It is found that ZnO–G prepared at 200 °C containing 2.5% graphene exhibits the highest activity which is three times as large as that of pure ZnO. The optimum ZnO–G catalyst still retains the 80% of the initial activity still after it has been used 5 times repeatedly, and exhibits larger rate for MB degradation than pure ZnO in each recycled time.