Affiliations 

  • 1 Micro/Nanophysics Research Laboratory, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia
  • 2 School of Engineering, Monash University Malaysia, 47500 Bandar Sunway, Selangor, Malaysia
  • 3 Research School of Chemistry, The Australian National University, Canberra, ACT 2601, Australia
  • 4 School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
J Phys Chem Lett, 2020 Jun 18;11(12):4655-4661.
PMID: 32453583 DOI: 10.1021/acs.jpclett.0c01227

Abstract

We reveal a unique mechanism by which pure water can be dissociated to form free radicals without requiring catalysts, electrolytes, or electrode contact by means of high-frequency nanometer-amplitude electromechanical surface vibrations in the form of surface acoustic waves (SAWs) generated on a piezoelectric substrate. The physical undulations associated with these mechanical waves, in concert with the evanescent electric field arising from the piezoelectric coupling, constitute half-wavelength "nanoelectrochemical cells" in which liquid is trapped within the SAW potential minima with vertical dimensions defined by the wave amplitude (∼10 nm), thereby forming highly confined polarized regions with intense electric field strengths that enable the breakdown of water. The ions and free radicals that are generated rapidly electromigrate under the high field intensity in addition to being convectively transported away from the cells by the bulk liquid recirculation generated by the acoustic excitation, thereby overcoming mass transport limitations that lead to ion recombination.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.