Investigation of ethanol vapor sensing properties of ZnO flower-like nanostructures

Abstract

ZnO flower-like nanostructures were synthesized using zinc nitrate, zinc acetate and zinc sulfate precursors by hydrothermal method. The samples were characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared analyses. All of the ZnO samples synthesized by the different precursors were crystallized in a same wurtzite hexagonal structure with different properties such as various morphologies, effective surface areas, concentrations of OH surface groups, and gas sensing performances. It was observed that flower-like ZnO nanostructures grown by zinc nitrate and zinc acetate included nanopetals with thicknesses of 30 and 50 nm, respectively. For the ZnO sample based on zinc sulfate, microspheres were constructed from nanoplatelets with thickness of 100 nm. The gas sensing properties of the samples toward ethanol vapor were examined and compared at various working temperatures. It was observed that ZnO[nitrate] nanoflower sample was the optimal choice for practical applications (with considerable sensitivity of 70% beside fast response time of 25–27 s at low working temperature of 130 C). The suitable ethanol sensing characteristics of ZnO[nitrate] sample was explained by its highly porous structure as the mean surface area of the samples calculated from BET method followed from ZnO[nitrate] > ZnO[acetate] > ZnO[sulfate] sequence