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.