Flexible, stable and self-powered two-dimensional layered nanocomposites (PANI@MoS₂) for trace ammonia gas detection

Reliable self-powered provision and stretchability are significant challenges for achieving portable gas detection, but reports have difficulties to achieve either so far. In this paper, 2D layered PANI@MoS₂ composite with promising energy storage and NH₃-sensitive properties was synthesized by NH₄⁺ insertion and in-situ growth technique. Because of the unique layered structure facilitating rapid reversible diffusion of charge ions, the energy storage properties of composite was significantly improved (838.7 F/g at 1A/g current density), and the assembled device could power a LED bulb for more than 20 min. Furthermore, due to the formation of p-n heterojunction and Schottky barrier between PANI and MoS₂, as well as the enhancement of PANI’s structure and dispersion via polystyrene sulfonic acid along with nylon filter membrane, the sensitivity of sensor film exceeded 287 Ω/ppm, and the theoretical detection limit even reached 0.662 ppb by calculation. Ultimately, benefit from the outstanding stability and stretchability of the devices, by integrating the supercapacitor and sensor film, a semi-quantitative, real-time detection of spoiled food and exhaled gas from people was achieved. The self-powered sensing device was anticipated to be an important candidate in flexible wearable sensing arena.