Abstract
The UV and humidity sensing properties of ZnO nanorods prepared by arc discharge have beenstudied. Scanning electron microscopy and photoluminescence spectroscopy were carriedout to analyze the morphology and optical properties of the as-synthesized ZnO nanorods.Proton induced x-ray emission was used to probe the impurities in the ZnO nanorods. Alarge quantity of high purity ZnO nanorod structures were obtained with lengths of 0.5–1 µm. The diameters of the as-synthesized ZnO nanorods were found to be between 40 and400 nm. The nanorods interlace with each other, forming 3D networks which make themsuitable for sensing application. The addition of a polymeric film-forming agent (BASFLUVISKOL® VA 64) improved the conductivity, as it facilitates the construction of conducting networks.Ultrasonication helped to separate the ZnO nanorods and disperse them evenly through the polymericagent. Improved photoconductivity was measured for a ZnO nanorod sensor annealed in air at200 °C for 30 min. The ZnO nanorod sensors showed a UV-sensitive photoconduction,where the photocurrent increased by nearly four orders of magnitude from2.7 × 10−10 to1.0 × 10−6 A at 18 V under 340 nm UV illumination. High humidity sensitivity and goodstability were also measured. The resistance of the ZnO nanorod sensor decreasedalmost linearly with increasing relative humidity (RH). The resistance of theZnO nanorods changed by approximately five orders of magnitude from4.35 × 1011 Ω in dry air (7%RH) to about 4.95 × 106 Ω in 95% RH air. It is experimentally demonstrated that ZnO nanorods obtained by the arcdischarge method show excellent performance and promise for applications in both UV andhumidity sensors.
Published Version
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