Corona poling-engineered filler-free piezoelectric PVDF membrane with dual functionality for cantilever nanogenerator and emulsion separation

Porous piezoelectric materials have shown great potential in energy and environmental applications, however the incorporation of foreign fillers invariably obscures the intrinsic piezoelectric response and complicates the structure-property interpretation of poly(vinylidene fluoride) (PVDF) membrane. Herein, we propose a filler-free paradigm by engineering an asymmetric porous PVDF membrane via phase separation and subsequent face-specific corona poling. The resulting membrane achieved a piezoelectric constant ( d 33 ) of up to 12 pC/N, with a reduced dielectric constant ( ε ) and loss factor (tan δ) . The intrinsic piezoelectric response of the filler-free porous PVDF membrane was elucidated based on the mechanism of the charge, current and voltage generation under the sinusoidal actuation. The piezoelectric charge output varied with poling direction, producing signals that were either in phase or shifted by π under identical mechanical input. When configured as a cantilever nanogenerator, the poled membrane generated a peak-to-peak voltage of 80 mV at its resonance frequency of 35 Hz, demonstrating its effective energy harvesting capability. In addition, the fabricated membrane exhibited high separation efficiency, achieving >99% turbidity rejection for both cationic and anionic surfactant-stabilized oil-in-water emulsions, demonstrating its versatile separation capacity. These findings highlight the potential of scalable, filler-free piezoelectric PVDF membranes as multifunctional platforms for sustainable energy and environmental applications.