UV and humidity sensing properties of ZnO nanorods prepared by the arc discharge method

Abstract

The UV and humidity sensing properties of ZnO nanorods prepared by arc discharge have been studied. Scanning electron microscopy and photoluminescence spectroscopy were carried out 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. A large quantity of high purity ZnO nanorod structures were obtained with lengths of 0.5-1 microm. The diameters of the as-synthesized ZnO nanorods were found to be between 40 and 400 nm. The nanorods interlace with each other, forming 3D networks which make them suitable for sensing application. The addition of a polymeric film-forming agent (BASF LUVISKOL 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 polymeric agent. Improved photoconductivity was measured for a ZnO nanorod sensor annealed in air at 200 degrees C for 30 min. The ZnO nanorod sensors showed a UV-sensitive photoconduction, where the photocurrent increased by nearly four orders of magnitude from 2.7 x 10(-10) to 1.0 x 10(-6) A at 18 V under 340 nm UV illumination. High humidity sensitivity and good stability were also measured. The resistance of the ZnO nanorod sensor decreased almost linearly with increasing relative humidity (RH). The resistance of the ZnO nanorods changed by approximately five orders of magnitude from 4.35 x 10(11) Omega in dry air (7% RH) to about 4.95 x 10(6) Omega in 95% RH air. It is experimentally demonstrated that ZnO nanorods obtained by the arc discharge method show excellent performance and promise for applications in both UV and humidity sensors.

The Study of Structural, Physical and Electrochemical Activity of Zno Nanoparticles Synthesized by Green Natural Extracts of Sageretia Thea

“…Especially, 2D ZnO nanosheets with mesoporous structures exhibit excellent gas sensing properties including high sensitivity, good selectivity and long-term stability [14,22,23]. Zn 5 (OH) 8 Cl 2 ·H 2 O, as one type of precursors to topologically produce ZnO nanomaterials, has also attracted attention for their gas sensing applications, such as hydrogen gas sensor with highly improved response of 55 at 300°C [14,23]. It has been reported that ZnO nanoparticles can readily agglomerate, owing to their high surface energy [24].…”

Comparative study on the properties of ZnO nanowires and nanocrystalline thin films

“…The interaction of water with ZnO surfaces is still poorly understood in part due to the complex mechanism of water adsorption on metal oxide surfaces, such as ZnO [31]. However, this effect has been already proposed to be used in the design of humidity sensors based on ZnO bulk [32], TFs [33,34], NWs [35,36], nanorods [37,38], and nanotubes [39].…”

Ultraviolet sensing based on nanostructured ZnO/Si surface acoustic wave devices

“…In addition, many UV sensors based on ZnO nanostructures as the sensing material have been reported, however, most of them are characterized by current-voltage measurement, not based on SAW measurment [25,[28][29][30]. In this work, we investigate two ways to improve the UV sensing response based on ZnO/Si SAW devices: one using Sezawa mode instead of Rayleigh mode, and the other using ZnO NRs instead of ZnO film as the sensing material.…”