Energy generation from airborne noise: Improving electrical outputs of single-layer polyvinylidene difluoride nanofiber membranes by incorporating a small number of nylon-6 nanofibers

Considerable research has been devoted to generating electricity from airborne noise. However, it is still a challenge to develop high-efficiency, large-output energy harvesters for this purpose. Herein, we present a novel approach to improve the electrical output of a noise-related energy harvester, made of single-layer polyvinylidene difluoride (PVDF) nanofiber membrane, simply by incorporating a small number of nylon-6 nanofibers into the PVDF fibrous matrix. The addition of just 4.3 wt% nylon-6 nanofibers profoundly improves the acoustoelectric conversion. In an airborne noise environment (e.g., 230 Hz 118 dB SPL), the device (working area 12 cm²) can generate peak electrical outputs as high as 201.4 V and 17.6 µA (power density 1.30 W/m²). The voltage and current outputs are 2.7 times and 2.6 times higher, respectively, compared to the pure PVDF nanofiber counterpart. The nylon-6/PVDF device also showed broader bandwidth, covering a frequency range of 230–800 Hz. The nylon-6 nanofibers were found to play dual roles in noise harvesting: 1) a tribo component to cause an endogenous triboelectric effect with PVDF nanofibers, and 2) a dopant to form macro dipoles, thus improving the charge transport from a dielectric layer to the external electrodes, which significantly increases the electrical outputs. Incorporating high polarity dopant may form a novel approach to improve the electrical outputs of acoustoelectric nanofibers.