Abstract
Carbon nanotubes (CNT) are extremely sensitive to environmental gases. However, detection of mixture gas is still a challenge. Here, we report that 10 ppm of carbon monoxide (CO) and ammonia (NH3) can be electrically detected using a carboxylic acid-functionalized single-walled carbon nanotubes (C-SWCNT). CO and NH3 gases were mixed carefully with the same concentrations of 10 ppm. Our sensor showed faster response to the CO gas than the NH3 gas. The sensing properties and effect of carboxylic acid group were demonstrated, and C-SWCNT sensors with good repeatability and fast responses over a range of concentrations may be used as a simple and effective detection method of CO and NH3 mixture gas.
Highlights
Among several applications using carbon nanotubes (CNT) [1], chemical gas sensors are currently regarded as one of the most promising application due to their fast response and high sensitivity toward gaseous molecules at low operational temperatures
Since the pristine single-walled carbon nanotubes (SWCNT) gas sensor was insensitive to carbon monoxide (CO) gas due to the low affinity to pristine SWCNT [19], we considered that highly carboxylic acid-functionalized single-walled carbon nanotubes (C-SWCNT) was responsible for the observed decrease in resistance under CO gas
The C-SWCNT-based sensor was used to detect the change of resistance when the sensor was exposed to three types of gases
Summary
Among several applications using carbon nanotubes (CNT) [1], chemical gas sensors are currently regarded as one of the most promising application due to their fast response and high sensitivity toward gaseous molecules at low operational temperatures. Considerable theoretical efforts have been devoted to the study of the possible interaction of a broad variety of gas molecules including H2, NH3, NO2, O2, and CO with CNT [2,3,4,5,6,7,8,9], these gases are frequently found in the polluted air from modern big cities. Upon exposure to gas molecules, the electrical resistance of single-walled carbon nanotubes (SWCNT) changes and the threshold voltage is shifted. Comparisons will be made with conventional sensors highlighting improved characteristics
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