High-Performance Flexible Piezoelectric Nanogenerator Assisted by a Three-phase PVDF/WS2/rGO Nanocomposite.

The emergence of piezoelectric nanogenerators presents a promising alternative to supply energy demands within the realms of portable and miniaturized devices. In this article, the role of 2D transition metal dichalcogenide (TMD) tungsten sulfide (WS2) and conductive rGO sheets as filler materials inside the polyvinylidene fluoride (PVDF) matrix on piezoelectric performances has been investigated extensively. The strong electrostatic interaction between C-F and C-H monomer bonds of PVDF interacted with the large surface area of the WS2 nanosheets, increasing the electroactive polar phases and resulting in enhanced ferroelectricity in the PVDF/WS2 nanocomposite. Further, the inclusion of rGO sheets in the PVDF/WS2 composite allows mobile charge carriers to move freely through the conductive network provided by the rGO basal planes, which improves the internal polarization of the PVDF/WS2/rGO nanocomposites and increases the electrical performance of the piezoelectric nanogenerators (PENGs). The PVDF/WS2/0.3rGO nanocomposite-based PENG exhibits maximum piezoresponses with ~8.1 times enhancements in the output power density than the bare PVDF-based PENG. The mechanism behind the enhanced piezoresponses in the PVDF/WS2/rGO nanocomposites has been discussed. .

A ferroelectric nanocomposite-film-based device for harvesting energy from water droplets using both piezoelectric and triboelectric effects.

In this paper, we have demonstrated a novel design of a liquid-solid interface triboelectric nanogenerator based on a ZnO- polyvinylidene fluoride (PVDF) flexible ferroelectric film that employs both piezoelectric and triboelectric properties to produce more electricity from water droplets. The present device gives an output voltage of ∼1.32 V and a short-circuit current of ∼0.32µA from the conventional liquid-solid triboelectric nanogenerator (LSTENG), while an additional open-circuit voltage of ∼2.72 mV and short-circuit current of ∼20 nA is generated from the piezoelectric effect. The mechanism for generating energy in both the piezoelectric and triboelectric components is also discussed. Furthermore, we explored the effect of ions in water on the performance of the LSTENG, and the results were confirmed by Kelvin probe force microscopy measurements. The current work reveals a new LSTENG design and the benefit of employing a ferroelectric polymer as the contacting material rather than other non-piezoelectric materials for the LSTENG.

PANI coupled hierarchical Bi2S3nanoflowers based hybrid nanocomposite for enhanced thermoelectric performance.

Bismuth sulfide (Bi2S3) is a promising material for thermoelectric applications owing to its non-toxicity and high abundance of bismuth (Bi) and sulfur (S) elements on earth. However, its low electrical conductivity drastically reduces the value of the figure of merit (ZT). In this work, we have synthesized three-dimensional (3D) hierarchical Bi2S3nanoflowers (NFs) by the hydrothermal route and further incorporated them with conducting polymer polyaniline (PANI) by simple chemisorption method. We have investigated the thermoelectric properties of the as-prepared Bi2S3NFs and PANI/Bi2S3nanocomposite samples and it is demonstrated that the incorporation of the PANI matrix with the 3D hierarchical Bi2S3NFs provides a conducting substrate for the easy transport of the electrons and reduces the barrier height at the interface, resulting in ∼62% increment in the electrical conductivity as compared to Bi2S3NFs. Moreover, a decrement in the thermal conductivity of the PANI/Bi2S3nanocomposite is observed as compared to pristine Bi2S3NFs due to the increased phonon scattering at the interfaces facilitated by the hierarchical morphology of the NFs. Furthermore, an increment in the electrical conductivity and simultaneous decrement in the thermal conductivity results in an overall ∼20% increment in the figure of merit (ZT) for PANI/Bi2S3nanocomposite as compared to pristine Bi2S3NFs. The work highlights an effective strategy of coupling 3D hierarchical metal chalcogenide with conducting polymer for optimizing their thermoelectric properties.