Selective Detection of NO<sub>2</sub> Using Cr-Doped CuO Nanorods

• Main Authors: Kang-Min Kim, Hyun-Mook Jeong, Hae-Ryong Kim, Kwon-Il Choi, Hyo-Joong Kim, Jong-Heun Lee
• Format: Article
• Language: English
• Published: MDPI AG 2012-06-01
• Series: Sensors
• Subjects: CuO; Cr<sub>2</sub>O<sub>3</sub> p-type; gas sensor; nanostructures; nanosheets; nanorods
• Online Access: http://www.mdpi.com/1424-8220/12/6/8013

CuO nanosheets, Cr-doped CuO nanosheets, and Cr-doped CuO nanorods were prepared by heating a slurry containing Cu-hydroxide/Cr-hydroxide. Their responses to 100 ppm NO<sub>2</sub>, C<sub>2</sub>H<sub>5</sub>OH, NH<sub>3</sub>, trimethylamine, C<sub>3</sub>H<sub>8</sub>, and CO were measured. For 2.2 at% Cr-doped CuO nanorods, the response (<em>R<sub>a</sub>/R<sub>g</sub></em>, <em>R<sub>a</sub></em>: resistance in air, <em>R<sub>g</sub></em>: resistance in gas) to 100 ppm NO<sub>2</sub> was 134.2 at 250 °C, which was significantly higher than that of pure CuO nano-sheets (<em>R<sub>a</sub>/R<sub>g</sub></em> = 7.5) and 0.76 at% Cr-doped CuO nanosheets (<em>R<sub>a</sub>/R<sub>g</sub></em> = 19.9). In addition, the sensitivity for NO<sub>2</sub> was also markedly enhanced by Cr doping. Highly sensitive and selective detection of NO<sub>2</sub> in 2.2 at% Cr-doped CuO nanorods is explained in relation to Cr-doping induced changes in donor density, morphology, and catalytic effects.