Self Assembled CdS/ZnO Core/Shell Nanorods Heterostructure: An Efficient and Stable Photocatalyst

Self assembled CdS/ZnO core/shell nanorods have been synthesized using a soft chemical route. The synthesis consists of a two step process involving first the synthesis of CdS nanorods by hydrothermal method and then growth of ZnO shell around CdS by self assembly using soft chemical method. X-ray photoelectron spectroscopy and Transmission electron microscopy (TEM) study confirms the formation of the CdS/ZnO core/shell nanostructure. The high resolution TEM image of the CdS/ZnO core/shell nanostructure shows a clear interface between the ZnO and CdS nanorods. The photocatalytic activity for the degradation of methylene blue (MB) organic dye and the stability of the CdS/ZnO nanostructure has been enhanced under the UV-visible irradiation at room temperature. The photodegradation results confirm the increased photocatalytic activity for the CdS/ZnO core/shell nanorods as compared to bare ZnO and CdS nanorods. The enhancement in the photocatalytic activity of CdS/ZnO is attributed to the formation of heterojunction between the CdS and ZnO which facilitates the efficient transport of photogenerated electron-hole pairs. The PL results confirm the transfer of the charge carriers from CdS to ZnO in CdS/ZnO core/shell nanostructure thereby preventing the electron-hole pair recombination. The CdS in CdS/ZnO core/shell nanostructure do not show any sign of photocorrosion due to the presence of stable ZnO as cap layer.