Bead Necklace-Shaped Single Walled Carbon Nanotube-Polypyrrole Nanocomposites for Ammonia Gas Sensor

The nanocomposite of bead necklace-like structure in which single stands of single-walled carbon nanotube (SWCNT) are impregnated in several polypyrrole (PPy)/phenylalanine (PA), PPy@PA, nanoparticles, with an average bead diameter of 80 nm and SWCNT length of 5 µm, as a sensing material for detecting ammonia gas, was synthesized by simple emulsion polymerization. The synthesized nanocomposite showed an electrical conductivity more than 5 times higher than that of PPy alone with a selective reactivity to ammonia gas. In addition, it exhibited a high sensitivity of less than 100 ppb at room temperature and was not significantly affected by the sensitivity even under the humidity conditions of 0 ∼70% RH (relative humidity). [graphic not available: see fulltext]