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TEMPO Monolayers on Si(100) Electrodes: Electrostatic Effects by the Electrolyte and Semiconductor Space-Charge on the Electroactivity of a Persistent Radical

Zhang, Long; Vogel, Yan Boris; Noble, Dr Benjamin; Gonçales, Vinicius R; Darwish, Nadim; Brun, Anton Le; Gooding, J Justin; Wallace, Gordon G; Coote, Michelle; Ciampi, Simone

Description

This work demonstrates the effect of electrostatic interactions on the electroactivity of a persistent organic free radical. This was achieved by chemisorption of molecules of 4-azido-2,2,6,6-tetramethyl-1-piperdinyloxy (4-azido-TEMPO) onto monolayer-modified Si(100) electrodes using a two-step chemical procedure to preserve the open-shell state and hence the electroactivity of the nitroxide radical. Kinetic and thermodynamic parameters for the surface electrochemical reaction are investigated...[Show more]

dc.contributor.authorZhang, Long
dc.contributor.authorVogel, Yan Boris
dc.contributor.authorNoble, Dr Benjamin
dc.contributor.authorGonçales, Vinicius R
dc.contributor.authorDarwish, Nadim
dc.contributor.authorBrun, Anton Le
dc.contributor.authorGooding, J Justin
dc.contributor.authorWallace, Gordon G
dc.contributor.authorCoote, Michelle
dc.contributor.authorCiampi, Simone
dc.date.accessioned2020-09-02T06:42:18Z
dc.date.available2020-09-02T06:42:18Z
dc.identifier.issn0002-7863
dc.identifier.urihttp://hdl.handle.net/1885/209240
dc.description.abstractThis work demonstrates the effect of electrostatic interactions on the electroactivity of a persistent organic free radical. This was achieved by chemisorption of molecules of 4-azido-2,2,6,6-tetramethyl-1-piperdinyloxy (4-azido-TEMPO) onto monolayer-modified Si(100) electrodes using a two-step chemical procedure to preserve the open-shell state and hence the electroactivity of the nitroxide radical. Kinetic and thermodynamic parameters for the surface electrochemical reaction are investigated experimentally and analyzed with the aid of electrochemical digital simulations and quantum-chemical calculations of a theoretical model of the tethered TEMPO system. Interactions between the electrolyte anions and the TEMPO grafted on highly doped, i.e., metallic, electrodes can be tuned to predictably manipulate the oxidizing power of surface nitroxide/oxoammonium redox couple, hence showing the practical importance of the electrostatics on the electrolyte side of the radical monolayer. Conversely, for monolayers prepared on the poorly doped electrodes, the electrostatic interactions between the tethered TEMPO units and the semiconductor-side, i.e., space-charge, become dominant and result in drastic kinetic changes to the electroactivity of the radical monolayer as well as electrochemical nonidealities that can be explained as an increase in the self-interaction "a" parameter that leads to the Frumkin isotherm.
dc.description.sponsorshipL.Z. thanks University of Wollongong and the for scholarship support. S.C. thanks the University of Wollongong for the Vice Chancellor Fellowship. Support from the Australian National Fabrication Facility (ANFF) Australian Institute of Nuclear Science and Engineering is acknowledged. V.R.G. thanks CAPES-Brazil (Proc. 12149-13-6) for the conceded scholarship. G.G.W., M.L.C., J.J.G., and S.C. gratefully acknowledge financial support from the Australian Research Council under their Centre of Excellence and Discovery Project Schemes (CE140100012, DP150103065) and generous allocations of supercomputing time on the National Facility of Australian National Computational Infrastructure is acknowledged.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherAmerican Chemical Society
dc.rights© 2016 American Chemical Society
dc.sourceJournal of the American Chemical Society
dc.titleTEMPO Monolayers on Si(100) Electrodes: Electrostatic Effects by the Electrolyte and Semiconductor Space-Charge on the Electroactivity of a Persistent Radical
dc.typeJournal article
local.identifier.citationvolume138
dc.date.issued2016
local.publisher.urlhttp://pubs.acs.org/journal/jacsat/about.html
local.type.statusAccepted Version
local.contributor.affiliationNoble, B., Research School of Chemistry, The Australian National University
local.contributor.affiliationCoote, Michelle, Research School of Chemistry, The Australian National University
dc.relationhttp://purl.org/au-research/grants/arc/CE140100012
dc.relationhttp://purl.org/au-research/grants/arc/DP150103065
local.identifier.essn1520-5126
local.bibliographicCitation.issue30
local.bibliographicCitation.startpage9611
local.bibliographicCitation.lastpage9619
local.identifier.doi10.1021/jacs.6b04788
dcterms.accessRightsOpen Access
dc.provenancehttps://v2.sherpa.ac.uk/id/publication/7788..."The Accepted Version can be archived in a non-commercial institutional repository. 12 months embargo." from SHERPA/RoMEO site (as at 2/09/2020). This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://dx.doi.org/10.1021/jacs.6b04788
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