PAN/MXene/ZnS:Cu composites fibers with enhanced piezoelectric and energy storage performance for development of flexible piezoelectric sensors

Electrospun nanofibers are widely used in flexible piezoelectric sensors. However, producing multifunctional sensors with comprehensive coverage and high sensitivity remains challenging. In this work, we designed a multifunctional and flexible piezoelectric sensor. We obtained polyacrylonitrile (PAN)/MXene/ZnS:Cu nanofibers by electrospinning, while the diameter of the nanofibers was characterized by using scanning electron microscopy, x-ray diffraction spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. X-ray diffraction and FTIR spectroscopy showed that the synergistic effect of MXene and ZnS:Cu promotes the content of planar zigzag conformation of PAN (94.16%). The ferroelectric and mechanical properties of the nanofibers were characterized by ferrometry and stretching, and their energy storage efficiency reached 94.05%, and the elongation at break increased to 97.5%. The piezoelectric sensor was fabricated with PAN/MXene/ZnS:Cu nanofibers. Under less pressure (0.098–1.96 N), it had a sensitivity of 2.46 V N⁻¹, and at a frequency of 3 Hz, using a slight force percussion, its output voltage reached 10 V, which was twice that of pure PAN nanofibers. The output current was 50 μA. Its good sensitivity could be used to detect small body movement signals. Our results showed that PAN/MXene/ZnS:Cu nanofibers can fabricate multifunctional sensors, and the excellent performance of the piezoelectric sensor makes it have great application potential in the next generation of wearable electronic products.