Synthesis and characterization of Cobalt-doped ZnO microstructures for methane gas sensing

Pure and Cobalt doped ZnO microstructures have been prepared by hydrothermal method and calcinations at 600 degrees C. The crystal structure, surface morphology and chemical composition of the samples were determined by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy, respectively, indicating that the presence of a small quantity of Co ions can greatly affect the morphology of the ZnO nanostructures. When used for methane gas sensing, 1 wt% Co/ZnO (CZ(1)) sensor exhibited the highest response to 100 ppm methane at 140 degrees C, which were about 2 times higher than that of pure ZnO samples. Moreover, the 1 wt% Co/ZnO sensor also displayed fast response/recovery time (19/27 s), low detection limit (50 ppb). Thus, the CZ(1) microstructures are promising for practical methane sensing applications. (C) 2015 Elsevier B.V. All rights reserved.