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Materials 2019, 12(3), 535; https://doi.org/10.3390/ma12030535

ZnO Synthesized Using Bipolar Electrochemistry: Structure and Activity

Department of Chemistry, University of New Brunswick, Fredericton, NB E3B 5A3, Canada
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Received: 31 December 2018 / Revised: 29 January 2019 / Accepted: 6 February 2019 / Published: 11 February 2019
(This article belongs to the Section Energy Materials)
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Abstract

The photoactive materials broadly applied in catalysis and energy conversion are generally composed of metal oxides. Among these oxides, ZnO showed a promising photocatalytic activity; however, traditional synthetic routes generated by-products and large amounts of secondary waste. Herein, we report the use of bipolar electrochemistry to generate ZnO nanoparticles using deionized water and a zinc metal to conform to green chemistry practices. TEM imaging demonstrated that the sizes of the bipolar-made ZnO particles were smaller than the commercial sample. The presence of structural defects in ZnO was correlated with the chemical shifts analyzed by X-ray photoelectron spectroscopy (XPS) and by different concentrations of O2− ions in stoichiometric and defected lattice. Further, the diffuse reflectance UV–Vis studies demonstrated a blue-shift in the reflectance spectrum for the bipolar-made oxide. This was also an indication of defects in the ZnO lattice, which related to the formation of shallow levels in the bandgap of the material. The structural and morphological differences influenced the photocatalytic characteristics, revealing a higher photocurrent for the bipolar-made ZnO when compared to the reference sample. This was further manifested in lower total resistivity for all anodes made from the non-stoichiometric ZnO, and also in their shorter diffusion length for charge exchange and electron lifetimes. View Full-Text
Keywords: bipolar electrochemistry; oxygen deficiency; zinc oxide; blue-shift; photocurrent; charge recombination; electron lifetime bipolar electrochemistry; oxygen deficiency; zinc oxide; blue-shift; photocurrent; charge recombination; electron lifetime
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Hakimian, A.; McWilliams, S.; Ignaszak, A. ZnO Synthesized Using Bipolar Electrochemistry: Structure and Activity. Materials 2019, 12, 535.

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