Single-layer piezoelectric nanofiber membrane with substantially enhanced noise-to-electricity conversion from endogenous triboelectricity

Conversion of airborne noise into usable electric energy brings multiple benefits for environmental protection but remains a challenge to achieve. Herein, we report a novel nanofiber membrane that shows unexpected enhancement in noise energy harvesting capability and electrical outputs. The nanofibers are prepared by electrospinning a polymer blend from polyacrylonitrile (PAN) and poly(vinylidene fluoride) (PVDF). Under noise environment, the device made of a 3 × 4 cm² PAN-PVDF nanofiber membrane can generate peak voltage outputs as high as 94.10 V and current output of 17.40 µA (14.5 mA/m²), with a power density of 250.1 mW/m² and energy conversion efficiency of 25.6%. The voltage outputs are 3.9 times higher than those of single-component PAN nanofibers and 4.5 times the single-component PVDF nanofibers in the same condition. Such unexpected noise-to-electricity conversion is originated from an endogenous triboelectric effect within the single layer fibrous membrane, which comes from the micro-phase separation of PAN and PVDF within the nanofibers making both components exposure to the fiber surface. Also, the ratio of the two polymer components in nanofibers affects the microstructure, molecular conformation of the polymers within the fibers, and energy conversion performance. The energy conversion is stable, and the electric power generated is sufficient to power various commercial equipment. To our knowledge, this is the first time to propose an endogenous triboelectricity within single-layer multi-component piezoelectric materials. It may form a novel concept to improve noise-to-electricity conversion and other energy harvesting technologies.