Selective detection of NO2 using Cr-doped CuO nanorods

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