High-sensitivity ammonia gas sensor based on hollow microsphere MXene@SnS2@polyaniline composite material with humidity resistance

Conductive polymer-based gas sensors are frequently utilized because of their benefits, which include affordability, good gas selectivity, and room-temperature detection. However, they are still limited by low sensitivity, high detection limit, and slow response-recovery speed. In this study, a hollow flower-shaped composite gas-sensing material was designed. MXene microspheres formed by electrostatic adsorption using Polymethyl Methacrylate (PMMA) as a template were used as substrates, and SnS2 nanosheets were produced hydrothermally on the MXene microsphere surface to form flower-shaped gas-sensitive materials. After calcination to remove the template, polyaniline (PANI) was coated onto each SnS2 nanosheet via in situ polymerization. The synthesized MXene@SnS2@PANI nanoflowering composites exhibited an extremely high responsiveness to ammonia gas at 25 °C, extremely low detection limits, and unique selectivity towards ammonia gas. When exposed to 100 ppm NH3 at 25 °C and 45% relative humidity (RH), the MSP-100 gas sensor's reaction reached 119.76%, which was five times that of PANI. Notably, in the range of 0%–90% RH, the MSP-100 based gas sensor's reaction grew as humidity rose, reaching a peak response of 215.18% at 90% RH. In addition, the MXene@SnS2@PANI based gas sensor had an extremely low detection limit of 1.557 ppm and prominent selectivity, indicating the its promising application in ammonia gas detection.