Highly sensitive and selective sensors to volatile organic compounds using MWCNTs/SnO2

Multiwall carbon nanotubes (MWCNTs)/SnO2 gas sensors were fabricated using ultrasonic-assisted deposition–precipitation method and used for detection of ethanol, acetaldehyde, acetone, toluene and trichloroethylene (TCE) VOCs at various temperatures. The MWCNTs/SnO2 samples were characterized by BET specific surface area measurement, FE-SEM and XRD. The sensors responses to 300 ppm of VOCs were measured in a flow system at various temperatures in the range of 100–350 °C. MWCNTs are coated with SnO2 nanoparticles and embedded into the SnO2 matrix. The sensors’ responses dramatically increase by adding 0.05 and 0.10 wt% MWCNTs to SnO2. Response enhancements up to 2.4, 4.4, 5.3, and 3.6 times are observed for ethanol, acetaldehyde, acetone and toluene, respectively. The 0.05 wt% MWCNTs/SnO2 sensor shows significant responses to sub-ppm levels of acetaldehyde and acetone, as the diabetes diagnostic gas in breath. Moreover, significant enhancement of the sensors selectivity to ethanol, acetaldehyde and acetone with respect to TCE and toluene are observed by addition of the MWCNTs.