Microwave-assisted synthesis of nickel sulfide/PANI composites for application in the detection of volatile organic compounds

The rapid industrialization and widespread use of volatile organic compounds (VOCs) have raised significant environmental and health concerns, necessitating the development of advanced gas sensors for precise detection and monitoring. Nickel sulfide (NiS, Ni 3 S 2 , and Ni 7 S 6 ) nanostructures were synthesized using a rapid, microwave-assisted method; polyaniline (PANI) was prepared using a rapid polymerization method; and nanocomposite structures of nickel sulphide and PANI were prepared via an ex-situ route for room-temperature gas sensing application. The nanocomposites were characterized using TEM, XRD, and BET analysis, revealing structural properties and enhanced surface area. The prepared nanocomposite sensors demonstrated superior sensitivity, selectivity, and stability towards butanol gas at 21 °C and 52 % relative humidity (RH). The NiS/PANI sensor exhibited a maximum response to butanol gas, three times that of pure PANI, while the Ni 7 S 6 /PANI nanocomposite sensor showed the lowest limit of detection (257 ppb) for butanol gas detection. The Ni 3 S 2 /PANI nanocomposite exhibited the fastest response time (65 s) and a low limit of detection (279 ppb). The nanocomposite sensors also demonstrated excellent repeatability and long-term stability over a period of 6 days, with minimal baseline drift. The proposed sensing mechanism involves the formation of P-N heterojunctions between nickel sulfides and PANI, facilitating efficient charge transfer and enhancing butanol adsorption. This study highlights the potential of unexplored nickel sulfide/PANI nanocomposites as potentially reliable, cost-effective, and environmentally friendly gas sensors for real-time butanol monitoring in manufacturing environments and their integrating into wearable devices for indoor pollution detection. • Nickel sulfide (NiS, Ni 3 S 2 , and Ni 7 S 6 ) nanostructures were synthesized using a rapid, microwave-assisted method • Ni x S y /PANI nanocomposite sensors showed a selective response to butanol vapor • Ni x S y /PANI nanocomposite sensors exhibited an improved baseline resistance and signal repeatability • Ni x S y /PANI nanocomposite sensors showed a response that is three times higher than bare PANI response • Measured sensing response stable over 6 days