Hierarchically architected polydopamine modified BaTiO3@P(VDF-TrFE) nanocomposite fiber mats for flexible piezoelectric nanogenerators and self-powered sensors

Flexible piezoelectric nanogenerators (FPENGs) have attracted a great attention owing to their promising applications in harvesting mechanical energy and driving portable devices. To develop high-performance FPENGs, the significant relationship among material, structure and performance inspired us a rational design of FPENGs from Pdop-BaTiO3@P(VDF-TrFE) nanocomposite fiber mats with a hierarchically architected microstructure. In contrast with previous approaches, the polydopamine (Pdop) modified barium titanate (BaTiO3, BT) nanoparticles have been anchored onto the surface of electrospun poly (vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) fibers to fabricate hierarchical micro-structured membrane in this study, which not only effectively avoids the agglomeration of nanofillers but also enhances the density of interfaces in the nanocomposites. As a result, the as-fabricated FPENGs show a significantly enhanced output of 6 V and 1.5 mu A as compared to the PENG with only P(VDF-TrFE) membrane (1.25 V and 0.6 mu A). Furthermore, output voltage of the new FPENGs is 40%-68% higher than that of composite membranes with nanoparticles at the interior of nanofibers. The improved output of the PENG is attributed to the high density of interfaces in the hierarchical microstructure and the corresponding enhancement of dielectric response. Then, electric performance of FPENGs was investigated in terms of force, frequency and load resistance. Finally, the FPENG was employed to efficiently detect human body movements as self-powered sensors. The hierarchical nanocomposite membrane designed in this study provides an effective approach for developing mechanical energy harvesters, wearable sensor network and self-powered devices.