Investigating gas sensing property of nanocomposites based on MWNTs or SWNTs and SnO_2

摘要

Composites made of oxygen functionalized multi-wall carbon nanotubes (MWNTs) and single-wall carbon nanotubes (SWNTs) coated with SnO_2 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 SnO_2. However, the sensitivity enhancement for the sensor made of SWNTs/SnO_2 composite was more pronounced, for e.g. the sensitivity of SWNTs/SnO_2 increased by a factor of 3 at 120°C and by a factor of 9 at 285°C compared to that of MWNTs/ SnO_2 sensor. SEM images of hybrid materials showed carbon nanotubes (CNTs) were embedded in SnO_2 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 SnO_2.