Graphene/Nickel Oxide-Based Nanocomposite of Polyanilinewith Special Reference toAmmonia Sensing

摘要

Polyaniline@grapheneickel oxide (Pani@GN/NiO), polyaniline/graphene (Pani/GN), and polyanilineickel oxide (Pani/NiO) nanocomposites and polyaniline (Pani) were successfully synthesized and tested for ammonia sensing. Pani@GN/NiO, Pani/NiO, Pani/GN, and Pani were characterized using X-ray diffraction, UV–vis spectroscopy, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy. The as-prepared materials were studied for comparative dc electrical conductivity and the change in their electrical conductivity on exposure to ammonia vapors followed by ambient air at room temperature. It was observed that the incorporation of GN/NiO in Pani showed about 99 times greater amplitude of conductivity change than pure Pani on exposure to ammonia vapors followed by ambient air. The fast response and excellent recovery time could probably be ascribed to the relatively high surface area of the Pani@GN/NiO nanocomposite, proper sensing channels, and efficaciously available active sites. Pani@GN/NiO was observed to show better selectivity toward ammonia because of thecomparatively high basic nature of ammonia than other volatile organiccompounds tested. The sensing mechanism was explained on the basisof the simple acid–base chemistry of Pani.