Selective Methanol Detection of Pyrolysis Grown Multiwalled Carbon Nanotubes

Abstract

Interest in vast response to external gas molecules by carbon nanotubes (CNTs) at ambient conditions potential for nanotubes based gas sensors. In this report, we synthesized carbon nanotubes using simple pyrolytic assisted growth process by varying temperatures (770, 870 and 970 °C). The pyrolysis grown multiwalled carbon nanotubes (MWCNTs) are found to be in well-ordered crystalline structure with significant higher graphitization degree and lower defect density resulting from structural and morphological analysis (TEM, Raman, FTIR and TG/DTA). The calculated ID/IG ratio reflects on decrease in structural defects of nanotubes on increasing the growth temperature from 770 to 970 °C. Two electrode based random network of CNTs sensor device are fabricated and applied for volatile organic compounds (Ethanol, Methanol, Acetone and Propan-2-ol) sensing. MWCNTs grown at 770 °C and 870 °C shows nearly equal response for Ethanol, Methanol, Acetone and Propan-2-ol gases. However, MWCNTs grown at 970 °C show selective sensing of methanol at room temperature. The calculated gas methanol gas sensitivity is about 35% with higher response and recovery time about ~6 and 10 sec respectively. This selective response for tested gases could be interesting for fabrication of CNTs based methanol sensors.