Room-temperature BTEX sensing characterization of nanostructured ZnO thin films

Nanostructured zinc oxide (ZnO) thin films were deposited on glass substrates using various molar concentrations of zinc acetate dihydrate as the starting precursor at 400 degrees C by the spray pyrolysis technique. The structural, morphological, and optical properties of the samples were investigated. X-ray diffraction studies showed thin films with a polycrystalline nature of the hexagonal wurtzite phase type. The preferred orientation was observed along the (002) direction. The crystallite size increased from 16.18nm to 20.42nm with increases in the molar concentration from 0.1M to 0.3M and then decreased further to 17.85nm at a molar concentration of 0.4M. SEM micrographs showed significant changes in the zinc oxide thin films with increases in the molar concentration of the precursor. Room-temperature Raman spectra confirmed typical electron-phonon coupling in the ZnO thin films. The optical band gap of the zinc oxide thin films was calculated using the Tauc plot. The sensitivity and selectivity of such toxic volatile organic vapors as benzene, toluene, ethylbenzene, and xylene (BTEX) were studied at room-temperature and reported.