Investigating gas sensing property of nanocomposites based on MWNTs or SWNTs and SnO2

摘要

Composites made of oxygen functionalized multi-wall carbon nanotubes (MWNTs) and single-wall carbon nanotubes (SWNTs) coated with SnO2 was synthesized by sonochemical coprecipitation method. Thick layer of these hybrid materials was used for fabrication of a sensor to detect 2-chloroethyl ethyl sulfide at low temperatures. The sensitivity of both sensors for detection of 100 ppm 2-chloroethyl ethyl sulfide improved compared to the sensor made of just blank SnO2. However, the sensitivity enhancement for the sensor made of SWNTs/SnO2 composite was more pronounced, for e.g. the sensitivity of SWNTs/SnO2 increased by a factor of 3 at 120°C and by a factor of 9 at 285°C compared to that of MWNTs/ SnO2 sensor. SEM images of hybrid materials showed carbon nanotubes (CNTs) were embedded in SnO2 matrix and also lower band gaps were observed in the presence of functionalized CNTs. The significant enhancement in gas sensitivity may be attributed to formation of p-n junction at the interface of CNTs and SnO2.