Synthesis of Ag-ZnS decorated multi-walled carbon nanotubes composite

In order to increment of the photocatalytic activity, nanosemiconductors can be decorated onto a proper support. Carbonaceous materials such as multi-walled carbon nanotubes (MWCNTs) are good hosts for semiconductors in catalytic reactions because of their sufficient stability, extraordinary structural, electrical and mechanical properties and non-toxicity [1,2]. In this research, Ag-ZnS nanoparticles were synthesized via a simple co-precipitation method and afterwards, Ag-ZnS decorated MWCNTs composite was prepared. The 0.5 M sodium sulfide aqueous solution was stirred in a three-neck round-bottom flask under the presence of nitrogen gas. Zinc acetate solution (0.5 M) with appropriate molar ratio of AgNO3 was slowly added to the above solution and stirred for another 30 min at room temperature. The resulting precipitate was collected by centrifugation and rinsed with ethanol and deionized water for several times. Afterward, MWCNTs powder was dispersed in 100 mL of water and sonicated for 15 min. Subsequently, the precipitates coming from the previous stage were added to the MWCNTs suspension under ultrasonic medium until the uniform precipitate was resulted. The resulting product was finally dried at room temperature and thereafter crushed to obtain fine powder. The prepared Ag-ZnS decorated MWCNTs composite was characterized in detail by X-ray diffraction (XRD, X’Pert Pro, Panalytical) and field emission scanning electron microscopy (FE-SEM, SIGMA, Zeiss). The XRD pattern of the composite included the characteristic peaks of ZnS with slightly lower crystallinity, which revealed that Ag-ZnS nanoparticles were successfully embedded in MWCNTs matrix. Also, according to the FE-SEM image, Ag-ZnS nanoparticles were well distributed in the MWCNTs matrix, which is supported by XRD analysis.