Synergistic effect of graphene nanosheet and BaTiO3 nanoparticles on performance enhancement of electrospun PVDF nanofiber mat for flexible piezoelectric nanogenerators

Piezoelectric nanogenerators (PENGs) with good flexibility and high outputs have promising and outstanding applications for harvesting mechanical energy and powering electronics. In this work, PENGs are fabricated by using electrospun nanocomposite fiber mats comprising barium titanate (BT) nanoparticles, graphene nanosheets and poly(vinylidene fluoride) (PVDF). When the nanocomposite fiber mats are composed of 0.15 wt% graphene nanosheets and 15 wt% BT nanoparticles, the open-circuit voltage and electric power of the PENG can reach as high as 11 V and 4.1 μW under a loading frequency of 2 Hz and a strain of 4 mm, and no apparent decline of the open-circuit voltage is observed after 1800 cycles in the durability test. In addition, the PENG generate a peak voltage as high as 112 V during a finger pressing-releasing process, which can light up 15 LEDs and drive an electric watch. The improved output of the PENG is ascribed to the synergistic contribution of the BT nanoparticles and graphene nanosheets to the piezoelectric performance enhancement of the nanocomposite fibers. This study shows that the nanocomposite fiber based flexible PENGs are promising mechanical energy harvesters and effective power sources for portable electronic and wearable devices.