Functionalized MWCNTs effects on dramatic enhancement of MWCNTs/SnO2 nanocomposite gas sensing properties at low temperatures

Multiwall carbon nanotubes (MWCNTs)/SnO2 nanocomposites containing 0.03-1.0 wt% MWCNTs were synthesized and used for the fabrication of gas sensors for ethanol, methane, CO and NO detection at low temperatures. Acid functionalized MWCNTs were dispersed in SnO2 using ultrasonic-assisted deposition-precipitation method. The nanocomposites were characterized by BET surface area measurement, FE-SEM, and XRD. The sensors response to 100 ppm ethanol, CO and NO and 1% CH4 were measured at a temperature range of 150-350 °C. The addition of carbon nanotubes causes up to 4.7 times decrease in SnO2 nanoparticles sizes. Our results indicate that 0.05 wt% is the optimum amount of carbon nanotubes, which remarkably increases the response of the SnO2-based sensors to all the gases. The most considerable response of 0.05 wt% MWCNTs/SnO2 nanocomposite sensor is related to CH4 detection, which is dramatically enhanced by a factor of 45 at 200 °C, compared to SnO2. Moreover, this sensor operating temperature for ethanol, CO and methane decrease by about 50-100 °C, upon addition of carbon nanotubes.