Preparation Of Reduced Graphene Oxide Comosites And And Their Photocatalytic Performance

Graphene, which arouses the enthusiasm of researcher after its pioneering isolation from graphite by Geim in 2004, opened up a new era of graphene. As a member of the carbon superfamily, it owns a single-atom-thick sheet(0.335nm) of hexagonally arrayed sp2-bonded carbon atoms and has attracted reasearchers’ eyeballs owing to its honeycomb network structure. The unique properties of graphene make it has excellent electron transfer rate, high conductivity and large specific surface area( theoretical calculation of graphene area is up to 2600 m2g-1) and et al. Therefore, it has been investigated and applied in electrical and optical devices and other fields. Graphene also has been regarded as one of the important material of synthesis of functional composite materials.Photocatalysis as a promising method to solve environmental pollution problems has been a hot research topic due to its mild reaction condition, high degradation, broad applied area and facile manipulation. Recently, due to its application in the fields of environmental protection and energy, the graphene and the combination of semiconductor nanostucture in the composite photocatalyst which has cause more and more attention. The synthesis methods of graphene based semiconductor photocatalyst mainly include the in situ growth method, solution mixing method and hydrothermal method. In this paper, graphite oxide(GO) was synthesized according to an improved Hummers method and a simply nontoxic hydrothermal approach is proposed for preparation of visible-light-responsive rGO-ZnO composites. The as-synthesized rGO–ZnO composites showed highly photocatalytic degradation efficiency of methylene blue(MB) under different illumination and were investigated by a series of techniques.(1) A series of Ce-doped ZnO(Ce/ZnO) nanostructures were fabricated using the co-precipitation method, a simply nontoxic hydrothermal approach is proposed for preparation of reduced graphene oxide(rGO)–Ce/ZnO composites. The prepared composites were investigated by a series of techniques. DRS spectrum demonstrated that rGO–2 can absorb more visible-light. The highly enhanced photoactivity of the composite is likely to be ascribed to great adsorption of dyes, retarded charge recombination rate, fast transfer processes and enhanced visible light absorption.(2) We use a simple, no template, one-step synthesized nitrogen doped graphene/ zinc oxide(NGZ) hybrid materials, which were characterized via analysis means, and its photocatalytic performance is studied with methylene blue(MB), and the results show that compared to the pure zinc oxide(ZnO) and reduced graphene oxide/zinc oxide(rGO-ZnO), NGZ photocatalyst has better photocatalytic performance. For the methylene blue(MB) solution, 99.98% of MB is removed with 60 min of UV irradiation, and the removal capacity of NGZ is almost 79.85% higher than the pure ZnO. The key factors in enhancing the removal capacity are the great adsorption performance of MB and the good conductivity of nitrogen doped graphene which can act as a good electron acceptor and electronic transmission in the photocatalytic process thus reducing the light pair of composite.(3) Reduced graphene oxide–ZnO/CuO composites with relatively high photocatalytic properties were synthesized by a simple, template-free, two-step hydrothermal method. The as-prepared composites were characterized by a series of techniques. The photocatalytic properties of the catalysts were evaluated by the degradation of MB under UV and sunlight irradiation. The results demonstrated that reduced graphene oxide–ZnO/CuO composites exhibited excellent catalytic property, which can be ascribed to the synergetic effects of the adsorptive power of reduced graphene oxide and the low recombination probability of photo-induced carriers. The composites may be a promising candidate for degradation of organic contaminants in water treatment.