Ultrathin Nb2CTx nanosheets-supported polyaniline nanocomposite: Enabling ultrasensitive NH3 detection

Abstract A novel NH3 sensor enabled by two dimensional (2D) niobium carbide MXene (Nb2CTx) nanosheets-supported polyaniline (PANI) nanocomposite (PANI/Nb2CTx) with enriched three dimensional (3D) spatial structure was successfully developed to achieve ultrasensitive NH3 detection under humidity atmosphere. The 2D ultrathin Nb2CTx nanosheets with abundant hydrophilic groups exhibited excellent regulation effect on the polymerization of PANI nanofibers and highly enhanced the morphology of PANI/Nb2CTx nanocomposite. The surface elemental analysis of Nb2CTx nanosheets was characterized through XPS, and the morphology images, crystal structure and chemical composition of the as-fabricated samples were investigated by FE-SEM, TEM, XRD and FTIR. According to the test results, the as-developed PANI/Nb2CTx sensor exhibits superior selectivity, high sensitivity, low detection limit (20 ppb) and good long-term reliability toward 0.1−10 ppm NH3 with 87.1 % RH. Owing to numerous hydrogen bonds between PANI and Nb2CTx, humidity affects on the sensing properties of PANI/Nb2CTx sensor was effectively reduced. Finally, the gas-sensing mechanism has been systematically studied to illustrate the improved sensing properties combining p-n junction with hydrogen bonds. This research provides a novel PANI/Nb2CTx NH3 sensor with excellent gas sensing properties, which can open up a new way to explore the application potential of Nb2CTx-based nanocomposite in both atmospheric and breath NH3 detection.