Microwave-Assisted Synthesis and Photocatalytic Properties of Carbon Nanotube/Zinc Sulfide Heterostructures

The multiwalled carbon nanotubes (MWCNTs) wrapped with face-centered cubic ZnS nanospheres with a uniform and small diameter have been prepared to form MWCNT/ZnS heterostructures by microwave irradiation. Zinc acetate (Zn(Ac)2) and thioacetamide (TAA) were used as the zinc and sulfur sources, respectively. The dispersion, morphology, ratio of loading, and size of the ZnS nanospheres in the range of 11.7 to 24.5 nm can be controlled easily by adjusting the microwave power, the initial concentration of Zn(Ac)2, and the molar ratios of Zn(Ac)2/TAA and Zn(Ac)2/MWCNTs. The heterostructures have been characterized by X-ray powder diffraction, and scanning and transmission electron microscopy. The results show that the surfaces of MWCNTs are not only randomly decorated with ZnS layers composed of uniform ZnS nanoparticles but also show that some spherelike ZnS nanoparticles are aggregated and deposited on the ZnS layers. A photoluminescence spectrum showed that the MWCNT/ZnS heterostructures feature a broad blue emission at around 432 nm (λex = 376 nm). The MWCNT/ZnS heterostructures also show an excellent photocatalytic activity toward the photodegradation of methyl orange.