Room temperature NO_2 gas sensing properties of p-toluenesulfonic acid doped silver-polypyrrole nanocomposite

摘要

Silver-polypyrrole nanocomposite (Ag-Ppy) films with different silver concentrations were synthesized without using any external oxidant i.e., with in-situ oxidation of pyrrole in the presence of silver nanoparticles. The gas sensing performance of all the films were investigated for NO, NO_2, NH_3, H_2S _{ethanol and methanol gases/vapours. The nanocomposite film was further doped with 05-25% p-toluenesulfonic acid (pTSA). Among various compositions, 15% pTSA doped Ag-Ppy thin films were found to be most sensitive and selective towards NO_2 gas at room temperatures. The films exhibited a chemiresitive response of 68% at 100 ppm NO_2 with a response time of 148 s and a recovery time of 500 s. The films exhibited 21% response for NO_2 even at low concentration levels at 5 ppm. The improved response kinematics is attributed to porous structure with faster charge transfer through ohmic contacts between polymer and silver nanoparticles upon interaction with gas.}