Flexible self-powered high-performance ammonia sensor based on Au-decorated MoSe2 nanoflowers driven by single layer MoS2-flake piezoelectric nanogenerator

Highlights: • A flexible piezoelectric nanogenerator (PENG) based on 2D single layer MoS₂ flake on PET was fabricated. • A room temperature high-performance Au-MoSe₂ composite based ammonia sensor was fabricated. • The Au-MoSe₂ composite-based ammonia sensor was self-powered by MoS₂ PENG and exhibited excellent properties. • The sensing mechanism of Au-MoSe₂ film toward ammonia gas was discussed by using first-principle calculations based on DFT. -- Abstract: Smart sensing devices with high reliability and self-powered features are critical in future generation wearable applications. In this paper, we reported for the first time a room temperature Au-MoSe₂ composite ammonia (NH₃) sensor driven by a novel flexible piezoelectric nanogenerator (PENG) based on two-dimensional (2D) semiconductor MoS₂ flake. Moreover, we also demonstrated the MoS₂-based PENG device attached to the human body for harvesting diverse body motion energy, demonstrating its strong potential for applications in wearable devices. A series of characterizations of 2D piezoelectric semiconductor MoS₂ and Au-MoSe₂ sensing materials were carried out. The Au-MoSe₂ composite-based ammonia sensor with MoS₂ PENG showed a higher response (V_a/V_g = 29 @ 100 ppm NH₃) toward NH₃ than that of MoSe₂ counterpart (V_a/V_g = 25 @ 100 ppm NH₃). And it has superior selectivity and outstanding long-term stability. Moreover, the sensor also has a fast response/recovery time (18 s/16 s) towards 20 ppm NH₃. Finally, the enhanced sensing mechanism of Au-MoSe₂ composite toward NH₃ was discussed by using first-principle calculations based on density functional theory.