| 초록 |
Nitrogen oxide NOx, a mixture of NO and NO2, is one of the typical air pollutants causing environmental problems. In this study, single wall carbon nanotubes (SWNTs) as a gas sensor to detect NOx is reported. SWNTs film was synthesized using the in-situ arc discharge method. The arc-discharge grown SWNTs showed porous structure and poor adhesion on the substrate. The ethanol treatment process, however, makes the porous SWNTs agglomerate together to form a film with good adhesion to the substrate. Scanning electron microscope was used to confirm the morphology of the SWNTs. The resistance of the SWNTs film can be controlled by the SWNT density. The gas sensing property of the SWNTs film was measured at room temperature. For the measurement of intrinsic response of SWNTs to the gases, pre-heating in vacuum was carried out to remove moisture out of the SWNT surface. Moisture is an important ingredient that affects the resistance of the SWNT films. Sensing properties for 60 ppm NOx were measured for various film thicknesses or resistances. The maximum sensitivity of SWNTs was about 95%. It was found that the sensitivity of SWNTs depends on its initial resistance. The film of higher resistance showed higher sensitivity possibly due to the larger surface/volume ratio. |
