Ultrasensitive flexible NH3 gas sensor based on polyaniline/SrGe4O9 nanocomposite with ppt-level detection ability at room temperature

Abstract

Detection limit as an important parameter of gas sensors, much effort has been devoted to developing high-performance gas sensors with low detection limit. However, the development of gas sensors with ppt-level detection limit still faces enormous challenges. In this work, a flexible and ultra-highly sensitive ammonia (NH3) sensor based on polyaniline/SrGe4O9 nanocomposites (PSN) was successfully fabricated via a facile in situ chemical oxidation polymerization method. When exposed to 0.2–10 ppm NH3 at 25 °C in 60% relative humidity (RH), the PSN sensor showed larger sensitivity (20.59% ppm−1) than that of PANI sensor (9.82% ppm−1). The response of the PSN sensor (16%) was two-fold higher than that of the PANI one (8%) to 0.2 ppm NH3 at room temperature. Meanwhile, the response time of the PSN sensor (24 s) was reduced to up to a third of that of the PANI sensor (64 s) for 800 ppb NH3. Additionally, the flexible PSN sensor exhibited good reproducibility, satisfactory long-term stability, excellent selectivity and outstanding flexibility to NH3 at room temperature. Significantly, the PSN sensor presented the ultra-low detection limit of 250 ppt toward NH3. Such outstanding gas-sensing properties were attributed to the unique hierarchical architecture with abundant mesoporous and the formation of p-n heterojunction at the interface between p-type PANI and n-type SrGe4O9. This research provides new strategies for developing high-performance NH3 sensors with supersensitive and ultra-low detection limit.