| Since the discovery of graphene in 2004,it has become a hot research topic because of its ideal two-dimensional crystal structure and unique physical properties.Up to now,there are several graphene preparation methods,such as micromechanical exfoliation,chemical vapour deposition,epitaxial growth method and the reduction of graphene oxide solution.The reduction of graphene oxide solution has some advantages compared with other approaches,including large-scale yield,low cost and easy processing,and expected to be an effective way for large-scale preparation of graphene.However,the reducing agent hydrazine hydrate and hydrazine often used in the reduction process is explosive and toxic,easy to cause damage to the environment.Therefore,there is a need for an environmentally friendly,gentle and effective method to achieve the bulk preparation of chemically reduced graphene oxide.(1)Graphene oxide was prepared by simplified Hummers method,modified Hummers method and pressurized oxidation method.The chemical composition and morphology were characterized by X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscopy,transmission electron microscopy and Fourier transform infrared spectroscopy.The results show that the modified Hummers method has a high degree of oxidation.(2)In the aqueous solution,the oxygen-containing group of graphene oxide was successfully removed by the reducing agent sodium humate,with strong reducing ability and environment friendly,and prepared stable and homogeneous chemically reduced graphene oxide suspension solution with the ratio of carbon to oxygen to 3.78.This preparation not only avoids the addition and use of toxic and harmful reducing agents and surfactants,but also provides a simple and environmentally friendly method for batch preparation of chemically reduced graphene oxide.(3)The graphene/nitrogen-doped zinc oxide composite photocatalyst was prepared by hydrothermal method.The optimum preparation conditions were as follows: the nitrogen doping amount was 0.4 g,the mass ratio of graphene oxide and nitrogen-doped zinc oxide was 5%,the hydrothermal temperature was at 120 °C.The photocatalytic activity of the as-prepared composite photocatalyst can reach 95% after 90 min photocatalytic reaction. |
