Fabrication of ZnO/CdS, ZnO/CdO core/shell nanorod arrays and investigation of their ethanol gas sensing properties

The sensing properties of ZnO/CdS and ZnO/CdO core/shell nanorod arrays were studied for ethanol gas sensing. ZnO nanorod arrays were synthesized on sputtered ZnO films through a simple hydrothermal method, and CdS films were then deposited on the ZnO nanorods by successive ionic layer adsorption and reaction (SILAR). After air annealing of the ZnO/CdS core/shell nanorods at 400 °C for 2 h, the CdS films were converted to CdO films. Using scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and diffused reflectance spectroscopy (DRS), ZnO/CdS and ZnO/CdO core/shell nanorod heterostructures were characterized. With respect to ethanol gas sensing, the ZnO/CdO core/shell nanorods exhibited highly enhanced responses compared to those of the ZnO/CdS core/shell nanorods. Based on the gas sensing mechanism, the effects of CdS and CdO shells on ZnO nanorod array gas sensors were discussed.