Vertically aligned zinc oxide nanowires electrodeposited within porous polycarbonate templates for vibrational energy harvesting

Abstract

A piezoelectric nanogenerator has been fabricated using a simple, fast and scalable template-assisted electrodeposition process, by which vertically aligned zinc oxide (ZnO) nanowires were directly grown within a nanoporous polycarbonate (PC) template. The nanowires, having average diameter 184 nm and length 12 μm, are polycrystalline and have a preferred orientation of the [100] axis parallel to the long axis. The output power density of a nanogenerator fabricated from the as-grown ZnO nanowires still embedded within the PC template was found to be 151 ± 25 mW m−3 at an impedance-matched load, when subjected to a low-level periodic (5 Hz) impacting force akin to gentle finger tapping. An energy conversion efficiency of ∼4.2% was evaluated for the electrodeposited ZnO nanowires, and the ZnO–PC composite nanogenerator was found to maintain good energy harvesting performance through 24 h of continuous fatigue testing. This is particularly significant given that ZnO-based nanostructures typically suffer from mechanical and/or environmental degradation that otherwise limits their applicability in vibrational energy harvesting. Our template-assisted synthesis of ZnO nanowires embedded within a protective polymer matrix through a single growth process is thus attractive for the fabrication of low-cost, robust and stable nanogenerators.

Nanostructured polymer-based piezoelectric and triboelectric materials and devices for energy harvesting applications

“…Removal of the template depends largely on the type of the template and the property of the polymer NWs, with common approaches including burning away the template [63] or chemical etching with solvent [38]. As for NG fabrication, sometimes the template removal process might be unnecessary as the template could serve to keep the NWs aligned with added mechanical advantages such as robustness and flexibility, and shielding from environ mental degradation [63,64]. A series of methods on the template-assisted growth of NWs, eventually aimed at fabrication of NGs are listed in figure 6.…”

“…Some examples of polymer-ceramic nanocomposite NGs using polymeric templates are also included in figures 6(d) and (e), where the piezoelectric active material is ZnO NWs. In these examples, the piezoelectric ZnO NWs were grown either by hydrothermal synthesis [64] ( figure 6(d)) or by electrodeposition [63] (figure 6(e)) within the nanopores of a polycarbonate template. All the template-assisted synthesis methods compared in this figure will be further discussed in detail in the following sections of the review.…”

Structure and Thermoelectric Properties of Bi2−xSbxTe3 Nanowires Grown in Flexible Nanoporous Polycarbonate Templates

“…Prior to electrodeposition, the templates were coated on one-side with a layer of 100 nm thick Au layer by sputtering (Emitech ® K550, Quorum Technologies Limited, Lewes, UK) (Panel B in Figure 1a). The Au layer serves as both nucleation sites and electrode contact for the growth of NWs inside the porous template during electrodeposition [34]. A glass slide coated with Au was then used to attach the Au-coated template secured with Kapton tape, and a copper wire was soldered to the template for electrical contact to the template during the electrodeposition process (Panel C in Figure 1a).…”

“…A Versastat4 ® from Princeton Applied Sciences was used to set up the potential difference and the data was recorded in VersaStudio ® [34,35]. Chronoamperometric electrodeposition (potentiostatic) was used where the potential difference and deposition time were varied and optimized to reach the optimum growth of the NWs and achieve maximum fill within the nanoporous PC templates (Panel D in Figure 1a).…”

Progress in Triboelectric Materials: Toward High Performance and Widespread Applications

“…To tackle energy shortages and content‐specific power supply requirements, researchers have designed a diversity of energy‐conversion devices derived from assorted working principles to collect energy, such as solar cells, electromagnetic generators, thermoelectric generators, piezoelectric nanogenerators, and triboelectric nanogenerators (TENGs) . Primarily benefiting from their light weight, low cost, multiple structures, extensive material selection, and even great efficiency at low operating frequencies, the novel TENGs have been proven as up‐and‐coming candidates to complementarily solve the energy‐ deficiency issue.…”