Synthesis Of CuS/ZnS Nanocomposites Decorated On Reduced Graphene Oxide And Their Photocatalytic Performance

Since the discovery of graphene in 2004, the synthesis and application of graphene-based nanocomposites have attracted considerable research interest all over the world. In this paper, a series of CuS/ZnS(CZS) nanocomposites decorated on reduced graphene(CZS/rGO) was fabricated via a hydrothermal method and a sonochemical process. The nanostructure, morphology and composition of CZS/rGO nanocomposites were confirmed by Scanning Electron Microscopy(SEM), X-ray Diffraction(XRD), Fourier-Transform Infrared Spectra(FT-IR), Thermal Gravimetric Analysis(TGA) and Raman Spectra and so on. The photocatalytic activity of as-synthesized nanocomposits was evaluated by photocatalytic degradation of MB solution under light irradiation.(1) Graphite oxide was prepared via a modified Hummers' method firstly, and a series of CZS/rGO nanocomposites with different weight ratios of rGO were fabricated via a two-step approach, in which CZS was synthesized first by a hydrothermal method, and then combined with rGO via a sonochemical process to form CZS/rGO nanocomposites, moreover, the schematic illustrations for the process to synthesize CZS/rGO nanocomposites was also proposed in this paper. The characterization results demonstrated that CZS/rGO nanocomposites were composed of the hexagonal phase CuS, the cubic phase ZnS and the lamellar structural rGO, CZS nanoparticles were decorated between rGO sheets homogeneously with intimate interfacial contact, and GO was successfully reduced into lamellar structural rGO by hydrazine. In addition, the effects of different preparation conditions on the morphology of CZS/rGO nanocomposites were researched in detail, and the optimal preparation conditions we obtained were that the optimal ultrasonic strength was 80% of the maximum ultrasonic power(500 W), the optimal ultrasonic time was1.5 h ~ 2 h, GO:hydrazine=10:8 by weight, and the optimal reaction solvent was deionized water.(2) The photocatalytic performance and mechanism of CZS/rGO nanocomposites were studied in this paper. The optical property of the as-prepared nanocomposites was characterized by the UV-vis absorption spectra. All the CZS/rGO nanocomposites had a broad absorption region in the visible range(450 nm ~ 780 nm) and a narrow absorption region in the UV range(250 nm ~ 400 nm). It demonstrated that the graphene-based nanocomposites possessed both UV and visible light response, which allowed them to be excellent candidates in photocatalytic field making full use of UV and visible light. The photocatalytic activity of as-synthesized nanocomposites was evaluated by photocatalytic degradation of MB solution under light irradiation. According to the experimental results, all the graphene-based nanocomposites showed more outstanding photocatalytic performance than pure CZS. And the larger amount of rGO one photocatalyst contained, the higher adsorption efficiency it possessed. Among all the graphene-based nanocomposites, CZS/rGO-4(rGO wt%=20%) exhibited the optimal photocatalytic performance, which was able to eliminate more than 99% of MB within 20 min, utilizing both UV and visible light, and exhibited no significant decrease in photodegradation efficiency after reuse in five cycles(99.39%).