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 δ′-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" δ′-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 δ′-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 δ′-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.
Bibliographical noteFunding Information:
This work was financially supported by a grant from the European Research Council through an ERC Starting Grant (Grant no. ERC-2014-STG-639526, NANOGEN). S. K.-N., Y. S. C. and A. D. are grateful for financial support from this same grant. Y. S. C. is grateful for studentship funding through the Cambridge Commonwealth, European & International Trust. Q. J. is grateful for financial support through a Marie Sklodowska Curie Fellowship, H2020-MSCAIF-2015-702868. CB thanks the EPSRC Cambridge NanoDTC, EP/G037221/1, for studentship funding. The authors thank Dr Thomas Bennett for discussions.
© The Royal Society of Chemistry.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Renewable Energy, Sustainability and the Environment
- Nuclear Energy and Engineering