Multi-Walled Carbon Nanotubes/ZnO Composite as Room Temperature Ethanol Vapor Sensor

ZnO nanoparticles were attached to the surface of multi-walled carbon nanotubes (MWCNTs) using wet chemical method to fabricate MWCNTs/ZnO nanocomposite to act as room temperature sensor for ethanol. The studied composites were characterized with HRTEM, EDX, XRD, FTIR, Raman, thermal analysis, and BET surface area. Furthermore, the effect of lyophilization (freeze-drying) and conventional drying on the properties and sensing behavior of the MWCNTs/ZnO was investigated. The results indicated that the peak values of surface areas were 346 cm2/g and 430 cm2/g for nonlyophilized and lyophilized MWCNTs/ZnO composites respectively. The gas sensing properties of MWCNTs/ZnO sensor was significantly improved after lyophilization. The lyophilized MWCNTs/ZnO sensor showed an enhancement about 33% and 26% as a result of their exposure to 1000 ppm and 3000 ppm of ethanol respectively, in comparison with non-lyophilized sensor.