Cobalt-polyoxometalate-PVDF nanofibers a flexible, self-powered and high-sensitive piezoelectric sensor

Abstract

This study investigates the enhancement of piezoelectric performance of polyvinylidene fluoride (PVDF) nanofibers with reduced graphene oxide (RGO)/polyoxometalate (POM) nanofillers. Synthesis of nanofibers by electrospinning technique led to alignment of molecular dipoles in nanofibers and supported polarization and stretching. Designed nanofibers was fully characterized and piezoelectric properties were measured and confirmed by a piezo tester device. The open-circuit voltage (V_OC) of the fabricated PENG was measured and results showed that PENG fabricated by PVDF-RGO-[(tert-Bu)₄N]₄PCoW₁₁O₃₉ (P-R-CoW) nanofiber, with a 1 wt% of CoW and 0.2 wt% of RGO with an V_OC of 6.75 ± 0.1 V revealed the best electrical performance. Using an electric circuit, capacitors of 1, 2.2, 4.7 and 10 μF were charged to 5.13, 1.77, 1.12 and 0.73 V respectively in 80 s. The maximum power density of 0.012 Wcm⁻² was obtained in the resistor 10³. The PENG was stable in long-term cycles without significant decreasing in V_OC. The output power of PENG turn on four commercial LEDs with 1.8 V and also a 5 V buzzer sounds. Piezoelectric energy generation from target PENG, could monitor simple human movements. For wrist and elbow at angles of 30, 60, 90º, and V_OC values 2.25 ± 0.15, 3.0 ± 0.2, 3.3 ± 0.1 and 4.4 ± 0.3, 5.0 ± 0.1, 5.2 ± 0.2 V respectively. Responses for heel force and finger tapping were 40.0 ± 2.0 and 14.4 ± 1.1 V respectively.