Growth mechanism of CuO one-dimensional nanostructures by thermal oxidation process and their CO gas sensing properties.

• Main Authors: Yao-Jhong Dong, 董耀中
• Other Authors: Yung-Chiun Her
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/95176930067603502799

碩士 === 國立中興大學 === 材料科學與工程學系所 === 98 === We have successfully synthesized one-dimensional CuO nanowires by thermal oxidation and observed their growth mechanism. The CuO nanowires were adopted to fabricate a simple gas sensor which can be used for detecting low concentration CO. In the atmosphere at temperatures between 300℃ to 600℃, CuO nanowires could be grown. Once the annealing temperature was higher than 700℃or lower than 200℃, no CuO nanowires could be formed. The varieties of synthesis temperature would affect the diameters of CuO nanowires, and the lengths of nanowires would increase with increasing synthesis time. The diameters of CuO nanowires synthesized at 450℃for 6 hours were approximately 130 nm, and the lengths could be up to 15μm or longer. It was found that the number of nanowires synthesized by thermal oxidation would decrease when the substrate was annealed for longer time, which suggests that the CuO nanowires might be grown by the anisotropic atomic diffusion mechanism. The as-synthesized CuO nanowires were indentified as a monoclinic crystal structure and cumulated along with (110) by XRD and TEM analysis. The gas sensor device fabricated by CuO nanowires exhibited good response capacity for detecting low CO concentration at an operating temperature of 300℃. The sensitivity of the gas sensor could be up to 181% at CO concentration of 50ppm, and could still reach 138% even if the CO concentration was as low as 5ppm. At low CO concentration, the response and recovery times for the gas sensor device were on average about 180 seconds and 220 seconds, respectively. Therefore, CuO nanowires have great potential for low- concentration CO gas sensor device.