Fabrication and ammonia gas sensing of palladium/polypyrrole nanocomposite

A nanocomposite of polypyrrole (Ppy) and palladium was fabricated by a facile method involving thermal dynamic refluxing of palladium salt and encapsulation of Pd nanoclusters with Ppy by vapor phase polymerization. The composite film was characterized using transmission electron microscopy and atomic force microscopy. It was found that the morphologies of the composite film were heavily affected by concentration and ratio of the reactants, polymerization time and polymer additives. The nanocomposite showed a response magnitude of 13.9–58.9% towards NH3 gas of 50–2000 ppm at room temperature, which is higher than that of Ppy alone by a factor of two. Moreover, the electrical response was reversible, reproducible and fast, with response and recovery times of 14 s and 148 s for 1000 ppm NH3, respectively. Gas sensory properties of the nanocomposite greatly depended on the size of Pd nanoparticles and the morphology of the composite film.