A novel SnO2 gas sensor doped with carbon nanotubes operating at room temperature

A new hybrid SWCNTs/SnO2 gas sensor is developed by adding single-walled carbon nanotubes (SWCNTs) into a SnO2 substrate. The fabrication involved heat-treating the SWCNTs/SnO2 layer, which was fabricated by spin coating using an organometallic solution of dispersed with SWCNTs. The hybrid sensor is utilized to detect NO2 concentrations in flowing air or N-2, by considering alterations in electrical proper-ties. The tests are performed at room temperature. Two hybrid sensors with different concentrations of SWCNTs are examined to elucidate the effect of a concentration of SWCNTs on the sensing properties of the sensors. A SnO2 sensor without SWCNTs, a blank sample, is also examined for comparison. Comparative gas sensing results reveal that the prepared hybrid SWCNTs/SnO2 sensors exhibit much higher sensing sensitivity and recovery property in detecting NO? gas at room temperature than the blank SnO2 sensor. This finding shows that doping with SWCNTs improves the sensitivity of hybrid sensors. Microstructural observations revealed that SWCNT bundles are embedded in the SnO2 matrix. Therefore, a model is presented to relate potential barriers to electronic conduction in the hybrid material. This model suggests that the high sensitivity is associated with the stretching of the depletion layers at the grain boundaries of SnO2 and the SWCNTs/SnO2 interfaces when detected gases are adsorbed. (C) 2004 Elsevier B.V. All rights reserved.