Physico-chemical and piezoelectric characterization of electroactive nanofabrics based on functionalized graphene/talc nanolayers/PVDF for energy harvesting

Poly(vinylidene fluoride) (PVDF) is a versatile polymer, whose dielectric, piezoelectric and ferroelectric properties can be augmented by a range of processing routes and/or additives. We developed a flexible nanogenerator using electrospun PVDF/COOH-functionalized graphene nanosheet (FGNS)/talc nanosheet (TNS) hybrid nanocomposites. TNS loading was fixed at 0.50 wt% while FGNS loading was varied (0.05, 0.10, 0.15, and 0.20 wt %) in these nanofabrics and their structure–property relationship was explored. Incorporation of FGNS led to formation of an electrically conductive network in the polymer matrix aided by TNS and electrospinning. The uniform dispersion of the filler nanosheets led to effective enhancement of the electroactive β-phase of the PVDF matrix. Crystallinity and polymorphism in these systems were explored by FTIR spectroscopy, X-ray diffraction and differential scanning calorimetry. A nanogenerator made of the nanofabric containing 0.5 wt% of TNS and 0.10 wt% of FGNS was mechanically impacted by pneumatic actuator (operating pressure 0.4 MPa), resulting in an output voltage of 12.9 V and a power density of 1.72 µW/cm², respectively. The piezoelectric coefficient (d₃₃) of this nanofiber system was 61 pm/V as revealed by piezoelectric force microscopy. These novel nanocomposites could be used in flexible energy-harvesting devices.