Synthesis of Zno/CNTS Nanocomposite Thin Film and Its Sensing

Abstract

Semiconductor metal oxides (SMOs) with nanostructures as gas sensing material have been widely used in detection of toxic gases and vapours. The gas sensing properties of the SMO-based sensors are highly dependent not only on their surface chemical reactivity and thermal stability but also on the geometrical and compositional variation. Nitrogen dioxide (NO2) is a typical air pollutant that causes environmental problems. The exact detection of ultra-low concentrations of NO2 is becoming very important now days. In order to enhance the sensitivity of carbon nanotube based chemical sensors at room temperature operation, SWCNTs/ZnO nanocomposite was prepared under chemical reaction condition. The layer of deposition was applied for the spin coating of the inner and outer SWCNTs walls with thin films of ZnO of precisely controlled thicknesses. Differently treated SWCNTs with different degree of surface functionalization were used as support for the oxide films. The sensing properties of the obtained composite materials towards NO2 were investigated and related to the morphological and microstructural characteristics of both the coating and support. ZnO-based composites on SWCNTs treated at 300 °C show enhanced performance as sensors, making them suitable for practical applications. Sensor structure showed a better sensing response (S ~ 1.51×10 2 ) at operating room temperature towards 20 ppm NO2 gas with an average response times of about 2.45 min.