Free Radical Generation from High-Frequency Electromechanical Dissociation of Pure Water

Amgad R. Rezk, Heba Ahmed, Tarra L. Brain, Jasmine O. Castro, Ming K. Tan, Julien Langley, Nicholas Cox, Joydip Mondal, Wu Li, Muthupandian Ashokkumar, Leslie Y. Yeo

    Research output: Contribution to journalArticlepeer-review

    28 Citations (Scopus)

    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.

    Original languageEnglish
    Pages (from-to)4655-4661
    Number of pages7
    JournalJournal of Physical Chemistry Letters
    Volume11
    Issue number12
    DOIs
    Publication statusPublished - 18 Jun 2020

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