Detection of a CO and NH(3) gas mixture using carboxylic acid-functionalized single-walled carbon nanotubes

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 (NH(3)) can be electrically detected using a carboxylic acid-functionalized single-walled carbon nanotubes (C-SWCNT). CO and NH(3) gases were mixed carefully with the same concentrations of 10 ppm. Our sensor showed faster response to the CO gas than the NH(3) 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 NH(3) mixture gas.