Improved sensing behavior of SnO2 functionalized carbon nanotubes towards NO2 and NH3

Single walled carbon nanotubes (SWNTs) films are prepared by dispersing SWNTs in DMF solution which is filtered over flexible polycarbonate membrane by vacuum filtration method. SWNTs film has been functionalized with different amounts (0.1 mg, 0.2 mg and 1 mg) of SnO2 nanoparticles of size 20-30 nm. Sensor is made by mounting a piece of CNT and different CNT/SnO2 films on PCB headers and contacts are taken by using Au wire. The sensing behavior of CNT/SnO2 towards NO2 and NH3 in the concentration range of 0.5 to 100 ppm has been studied. The sensing response has been compared to that obtained from pristine SWNTs. SWNTs with 0.1 mg of SnO2 has given the maximum improvement of 1.6-8.5% and 0.8-1.75 times in response for NH3 and NO2 respectively, as compared to pristine CNTs..