Nanogenerators of acid‐functionalized multiwalled carbon nanotubes incorporated poly(vinylidene fluoride) nanocomposites with enhanced piezoelectric performance towards bio‐mechanical motion energy harvesting

Abstract Polymer‐based piezoelectric nanocomposites, enhanced with nanofillers, offer a scalable solution for efficient energy harvesting. In this work, we incorporated acid‐functionalized multi‐walled carbon nanotubes (MWCNTs‐COOH) in poly(vinylidene fluoride) (PVDF) matrix to understand the influence of MWCNTs‐COOH in enhancing the overall structural, morphological, dielectric, and piezoelectric properties of the PVDF/MWCNTs‐COOH nanocomposites. The PVDF/MWCNTs‐COOH nanocomposites were prepared by melt‐mixing followed by solution casting, and the concentration of MWCNTs‐COOH was varied from 0 to 3 wt%. MWCNTs‐COOH served as a heterogeneous nucleating agent to form the polar crystalline polymorph of PVDF. The incorporation of 1.5 wt% of MWCNTs‐COOH led to the highest polar phase content of ~ 89% owing to the uniform dispersion of MWCNTs‐COOH in the PVDF matrix. Similarly, the highest piezoelectric coefficient (d 33 ) of ~ 49.2 pm/V was observed in the PVDF nanocomposite with 1.5 wt% of MWCNTs‐COOH. The fabricated optimized piezoelectric nanogenerator with 1.5 wt% of MWCNTs‐COOH exhibited the highest piezoelectric response with a sensitivity of ~ 11.4 V/N and an open circuit voltage of ~ 59.2 V, an open circuit current of ~ 3 μA, and a maximum power density of ~ 19.8 μW/cm 2 . The optimized device was found to exhibit high durability, which was confirmed by performing the durability test for 3 months consecutively. The fabricated device can be used as a sensor as well as an energy harvesting device for various bio‐mechanical motions. Highlights PVDF/MWCNTs‐COOH nanocomposites were used to fabricate nanogenerators. Higher extents of interfacial interactions enhanced piezoelectric performance. Nanocomposite of 1.5 wt% MWCNTs‐COOH showed a polar phase content of ~ 89%. Nanocomposite of 1.5 wt% MWCNTs‐COOH exhibited a d 33 value of ~ 49.2 pm/V. Nanogenerator utilized as a bio‐mechanical motion energy harvester.