Piezoelectric polymers, capable of converting mechanical vibrations into electrical energy, are attractive for use in vibrational energy harvesting due to their flexibility, robustness, ease and low cost of fabrication. In particular, piezoelectric polymers nanostructures have been found to exhibit higher crystallinity, higher piezoelectric coefficients and 'self-poling', as compared to films or bulk. The research in this area has been mainly dominated by polyvinylidene fluoride (PVDF) and its co-polymers, which while promising, have a limited temperature range of operation due to their low Curie and/or melting temperatures. Here, we report the fabrication and properties of vertically aligned, and 'self-poled' piezoelectric Nylon-11 nanowires with a melting temperature of ~200 °C, grown by a facile and scalable capillary wetting technique. We show that a simple nanogenerator comprising as-grown Nylon-11 nanowires, embedded in an anodized alumina (AAO) template, can produce an open-circuit voltage of 1 V and short-circuit current of 100 nA, when subjected to small-amplitude, low-frequency vibrations. Importantly, the resulting nanogenerator is shown to exhibit excellent fatigue performance and high temperature stability. Our work thus offers the possibility of exploiting a previously unexplored low-cost piezoelectric polymer for nanowire-based energy harvesting, particularly at temperatures well above room-temperature.

Triboelectric generators have emerged as potential candidates for mechanical energy harvesting, relying on motion-generated surface charge transfer between materials with different electron affinities. In this regard, synthetic organic materials with strong electron-donating tendencies are far less common than their electron-accepting counterparts. Nylons are notable exceptions, with odd-numbered Nylons such as Nylon-11, exhibiting electric polarisation that could further enhance the surface charge density crucial to triboelectric generator performance. However, the fabrication of Nylon-11 in the required polarised d 0 -phase typically requires extremely rapid crystallisation, such as melt-quenching, as well as ''poling'' via mechanical stretching and/or large electric fields for dipolar alignment. Here, we propose an alternative one-step, near room-temperature fabrication method, namely gas-flow assisted nano-template (GANT) infiltration, by which highly crystalline ''self-poled'' d 0 -phase Nylon-11 nanowires are grown from solution within nanoporous anodised aluminium oxide (AAO) templates. Our gas-flow assisted method allows for controlled crystallisation of the d 0 -phase of Nylon-11 through rapid solvent evaporation and an artificially generated extreme temperature gradient within the nanopores of the AAO template, as accurately predicted by finite-element simulations. Furthermore, preferential crystal orientation originating from template-induced nano-confinement effects leads to self-poled d 0 -phase Nylon-11 nanowires with higher surface charge distribution than melt-quenched Nylon-11 films, as observed by Kelvin probe force microscopy (KPFM). Correspondingly, a triboelectric nanogenerator (TENG) device based on as-grown templated Nylon-11 nanowires fabricated via GANT infiltration showed a ten-fold increase in output power density as compared to an aluminium-based triboelectric generator, when subjected to identical mechanical excitations. Broader contextEnergy harvesting from ubiquitous ambient vibrations represents a viable energy solution for the rapidly increasing number of low-power autonomous, wireless, portable and wearable electronic devices. Triboelectric generators have recently generated tremendous interest in this regard as they are capable of converting mechanical energy from the relative motion of two dissimilar materials into useful electricity, based on contact electrification and electrostatic induction arising from the materials having different electron affinities. In order to achieve high levels of energy harvesting performance, materials with electron-donating tendencies must be paired with those with electron-accepting tendencies. The bulk of the literature focuses on the latter, as these typically include materials that are easier to synthesise. Nylon-11 belongs to the less-explored family of synthetic and organic electron-donating materials, although the crystalline phase required for superior triboelectric performance has remained elusive in the bulk due to the typically harsh p...

Thermoelectric materials, capable of interconverting heat and electricity, are attractive for applications in thermal energy harvesting as a means to power wireless sensors, wearable devices, and portable electronics. However, traditional inorganic thermoelectric materials pose significant challenges due to high cost, toxicity, scarcity, and brittleness, particularly when it comes to applications requiring flexibility. Here, we investigate organic–inorganic nanocomposites that have been developed from bespoke inks which are printed via an aerosol jet printing method onto flexible substrates. For this purpose, a novel in situ aerosol mixing method has been developed to ensure uniform distribution of Bi2Te3/Sb2Te3 nanocrystals, fabricated by a scalable solvothermal synthesis method, within a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate matrix. The thermoelectric properties of the resulting printed nanocomposite structures have been evaluated as a function of composition, and the power factor was found to be maximum (∼30 μW/mK2) for a nominal loading fraction of 85 wt % Sb2Te3 nanoflakes. Importantly, the printed nanocomposites were found to be stable and robust upon repeated flexing to curvatures up to 300 m–1, making these hybrid materials particularly suitable for flexible thermoelectric applications.

The synthesis of CdS/ZnS core/shell nanorods was achieved via a three-step method involving solvothermal preparation of CdS nanorods and then a soft chemical process for functionalization of the CdS surface and subsequent ZnS shell growth. Citric acid was used as the surface functionalizing agent, which ensured the growth of a uniform ZnS shell covering the nanorod surface. The carboxyl groups of citric acid trapped on the surfaces of CdS nanorods with an outward orientation of the -OH functional groups made the surfaces of the nanorods negatively charged, directed the Zn 2+ ions to attach to the -OH ions, and helped the formation of a uniform ZnS shell following the addition of a sulfur source. The core/shell nanostructure was confirmed by X-ray study, transmission electron microscopy, and energy dispersive X-ray analysis. The photoluminescence efficiencies and electrical response of the CdS/ZnS core/shell nanorods were significantly enhanced as compared to those of the uncoated CdS nanorods, owing to the effective passivation of the surface electronic states of the CdS cores by the ZnS shell. The present synthesis provides a rational approach to the design of novel core/shell nanomaterials with appealing applications in optoelectronic devices.

In 2 S 3 micropompons composed of randomly oriented flakes of ∼10 nm thickness were synthesized in high yield by a facile hydrothermal process. When the product was thermally oxidized at 600°C, single crystalline well-faceted body-centered cubic (bcc) In 2 O 3 bipyramids of sizes between 50 and 300 nm were obtained. It was proposed that the growth of the In 2 S 3 nanoflakes was initially controlled by the Ostwald ripening process, and finally the aggregation of the flakes led to the development of the micropompons. The growth of the In 2 O 3 bipyramids from the In 2 S 3 micropompons started with the formation of In 2 O 3 nulclei at the surface of the micropompons causing the destruction of the flakelike structure to produce In 2 O 3 bipyramids. The micropompons showed good optical properties due to a strong quantum confinement effect. In 2 O 3 bipyramids showed near-band-edge (NBE) UV emission, which was mainly attributed to the high crystal quality of the bipyramids. The study may provide guidance for the morphology controllable synthesis of different nanostructures and may help in exploring the crystal growth process.