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Abstract Energy conversion and storage devices are considered to be potential candidates for application in health monitoring, smart-sensor and clean-energy harvesting. In this study, Li+ modified montmorillonite/poly(vinylidene fluoride-co-hexafluoropropylene) (MMT(Li)/PVDF-HFP) with energy conversion and storage abilities were prepared, and the effects of Li+ ions and adsorbed water on phase transformation as well as dielectric and piezoelectric performance were studied. MMT(Li)/PVDF-HFP composite film with 15 wt% MMT and 1.72 wt% H 2 O exhibited the good energy conversion and storage performances with high dielectric constant, generated current, open circuit voltage and holding time because of the Li+ polarization and β-phase nucleation by hydrogen bonds. Therefore, MMT modified by ion and H 2 O was an effective reinforce filler to prepare excellent energy conversion and storage film. We hope this modification method could inspire the performance optimization of other clay/polymer in the flexible electronic field. [ABSTRACT FROM AUTHOR]

Electrochemically up-regulated surface-enhanced Raman spectroscopy (E-SERS) effectively increases Raman signal intensities. However, the instrumental requirements and the conventional measurement conditions in an electrolyte cell have hampered its application in fast and on-site detection. To circumvent the inconveniences of E-SERS, we propose a self-energizing substrate that provides electrical potential by converting film deformation from a finger press into stored electrical energy. The substrate combines an energy conversion film and a SERS-active Ag nanowire layer. A composite film prepared from a piezoelectric polymer matrix and surface-engineered rGO that simultaneously presents high permittivity and low dielectric loss is the key component herein. Using our substrate, increased E-SERS signals up to 10 times from a variety of molecules were obtained in the open air. Various tests on real-life sample surfaces demonstrated the potentials of the substrate in fast on-site detection. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF)-based piezoelectric nanogenerators (PENGs), which are prepared by electrospinning, are widely used in self-powered field owing to their exceptional generation performance. The generation performance of fiber PENG is usually attributed to piezoelectric effect, but the effect of triboelectricity generated among the fibers on the generation performance is not negligible. On the other hand, quantifying triboelectricity and piezoelectricity and revealing the mechanism of triboelectric–piezoelectric synergy to enhance the generation performance are urgent issues of concern. In this study, hydroxyapatite (HAP) was added into PVDF–hexafluoropropylene (HFP) as a filler to prepare nanofiber films by electrospinning. Compared with a pure PVDF–HFP nanofiber film, the generation performance of a 25 wt% HAP/PVDF–HFP nanofiber film improved from 0.2 to 1.1 V. The HAP enhancement effect was verified by HAP-content experiment and work-function measurement. The contributions of triboelectricity and piezoelectricity were 62.5% and 37.5%, respectively, calculated using the thermal-treatment experimental results. Finally, the ultraviolet photoelectron-spectrum method and model analysis revealed the synergistic effect of triboelectricity and piezoelectricity. This work employed the thermal-treatment method to quantify the contributions of triboelectricity and piezoelectricity while providing an insight into the design of PVDF fiber PENG to further enhances the generation performance. [Display omitted] • The addition of HAP had a positive effect on the enhancement of triboelectricity generation. • Thermal-treatment method can control triboelectricity to quantify the contribution of triboelectricity and piezoelectricity. • The contributions of triboelectricity and piezoelectricity in HAP/PVDF-HFP fiber-film nanogenerator were 62.5% and 37.5%. • The piezoelectric field can modulate the direction of triboelectricity generation to achieve synergistic output. [ABSTRACT FROM AUTHOR]

We propose a porous piezoelectric-dielectric flexible composite energy conversion film for electricity generation from multiple sources. • The new modifier PFOES modified graphene successfully, and properties of composite films have been improved. • Porous films prepared by structural engineering further enhance the power generation and storage capacity. • The composite films generate electricity from either deformation or simulated solar irradiation. • DFT simulation is employed to verify the mechanism underlining the simultaneous advantageous piezoelectrical and pyroelectrical properties. In this study, we prepared polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) membranes with fluorosilane-modified graphene sheets (rGO-PFOES) as fillers by a solution casting method, and Conducted research on dielectric, piezoelectric, energy conversion, and storage properties. The filler presents denser DOS than neat rGO and is effective in photothermal conversion. Because of such merits, the films not only convert mechanical disturbance into electricity, but also generate electricity under simulated solar irradiation. Furthermore, we prepared porous films and the porosity significantly enhanced the piezoelectricity of the polymer film. The piezoelectric voltage and piezoelectric current of the film can reach 8.8 V and 600nA respectively. [ABSTRACT FROM AUTHOR]