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 °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 (CZ1) sensor exhibited the highest response to 100 ppm methane at 140 °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 CZ1 microstructures are promising for practical methane sensing applications.