Room-temperature gas sensing properties of cobalt-doped ZnO Nanobelts with visible light irradiation

Cobalt-doped ZnO (Co:Zn is 1, 3 and 5 mol%) nanobelts were prepared by a multi-components precursor self-assembled method, and characterized by the scanning electronic microscopy (SEM), X-ray diffraction (XRD), surface photocurrent spectroscopy and surface photovoltage spectroscopy. The room-temperature gas sensing of oxygen and ethanol vapor was measured with irradiation of visible light. The sensitivity is decreased on increasing the doped concentration. The cobalt-doped ZnO (1%) showed higher sensitivity and faster response rate to ethanol than to oxygen. The results are due to a large amount of photo-generated holes left in the surface of cobalt-doped ZnO (1%) nanobelts. And the changed photocurrent intensity was linear as function of the ethanol vapor.