Nanocomposite of Nitrogen-Doped Graphene/Polyaniline for Enhanced Ammonia Gas Detection

Graphene nanosheets are widely used for designing functional nanocomposite sensors that are highly sensitive. In this study, nitrogen-doped reduced graphene oxide (N-rGO) polyaniline (PANI) nanocomposites composed of localized heterojunctions are prepared for the detection of ammonia, dimethylamine, and trimethylamine gases with superior sensing performances. rGO nanosheets with electrical properties modified via N-doping are strategically incorporated in p-type PANI via in situ synthesis, with the nanosheets acting as templates for PANI growth. N-rGO nanosheets featuring large specific area, high electrical conductivity, and n-type semiconductive behavior combined with the attractive electrical p-type characteristics of PANI are found to be highly beneficial for improving detection sensitivity toward ammonia, dimethylamine, and trimethylamine gases at 25 degrees C. Overall, the detection sensitivity of the advanced N-rGO nanocomposites is more than two times higher than that of PANI alone. Moreover, the N-rGO/PANI nanocomposites reach an estimated limit of detection for ammonia gas down to the sub-ppm range. Improvement in sensing performance is also observed for rGO/PANI and GO/PANI nanocomposites; however, the level of the improvement is less than that of N-rGO/PANI nanocomposites. This study demonstrates the excellent potential of designing advanced graphene nanocomposite gas sensors with superior performances by manipulating the electronic properties of the graphene nanosheets.