3D flower- and 2D sheet-like CuO nanostructures: Microwave-assisted synthesis and application in gas sensors

3D flower-and 2D branching sheet-like CuO nanostructures have been synthesized by a microwave-assisted hydrothermal method. The samples were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy( IR), UV-vis diffuse reflectance spectroscopy (UV-DRS), and Brunauer-Emmett-Teller (BET) specific surface area analysis. The phase and morphology observations showed the formation of monoclinic CuOnanostructures with well-defined morphology. BET analysis displayed that the measured surface areawas 15.0 m(2)g(-1)for CuO flowers, and 20.8m(2)g(-1)for CuO nanosheets. Gas sensing properties of the as synthesized CuO nanostructures were evaluated by the detection of volatile and toxic gases including ethanol, ethyl-acetate, acetone, xylene, and toluene. It was found that CuO flowers exhibited an enhanced gas response to the five gases at 260 degrees C, compared to CuO nanosheets. Furthermore, at 1000 ppm, the CuO flower sensor gave a higher response to ethyl-acetate (R-g/R-a = 4.6) and ethanol (R-g/R-a = 4.0), in comparison with toluene (R-g/R-a = 2.8). In addition, the CuO flowers displayed a rapid response and recovery as well as good reproducibility. (C) 2014 Elsevier B.V. All rights reserved.