Influence of Cu and Ni dopants on the sensing properties of ZnO gas sensor

In this work, the influence of Cu and Ni doping on the propane gas (C3H8) detection of zinc oxide (ZnO) samples was evaluated. Three powder samples: (a) pure ZnO, (b) Ni-doped ZnO, and (c) Cu-doped ZnO, were obtained by homogenous precipitation method. The Ni and Cu concentration was of 1 at.%. The X-ray diffractograms indicate that all samples showed a hexagonal wurtzite-type crystal structure. Micrographs obtained by scanning electron microscopy (SEM) show a spherical surface morphology typical of nanostructured materials in the pure ZnO and ZnO/Ni samples. The gas sensing devices were manufactured by pressing the powders in pellets form. The sensing response of all pellets was measured by the surface electrical resistance change in a propane (C3H8) atmosphere at concentrations from 0 to 500 ppm at different operation temperatures (100, 200, and 300 °C). ZnO/Cu pellet presented the highest resistance change, registered at 300 °C in a propane concentration of 500 ppm.