Electro-polymerization rates of diazonium salts are dependent on the crystal orientation of the surface

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dc.contributor.authorRahpeima, Sen_AU
dc.contributor.authorLe Brun, APen_AU
dc.contributor.authorRaston, CLen_AU
dc.contributor.authorDarwish, Nen_AU
dc.date.accessioned2024-08-25T23:43:31Zen_AU
dc.date.available2024-08-25T23:43:31Zen_AU
dc.date.issued2022-11-15en_AU
dc.date.statistics2024-08-26en_AU
dc.description.abstractElectro-polymerization of diazonium salts is widely used for modifying surfaces with thin organic films. Initially this method was primarily applied to carbon, then to metals, and more recently to semiconducting Si. Unlike on other surfaces, electrochemical reduction of diazonium salts on Si, which is one of the most industrially dominant material, is not well understood. Here, we report the electrochemical reduction of diazonium salts on a range of silicon electrodes of different crystal orientations (111, 211, 311, 411, and 100). We show that the kinetics of surface reaction and the reduction potential is Si crystal-facet dependent and is more favorable in the hierarchical order (1 1 1) > (2 1 1) > (3 1 1) > (4 1 1) > (1 0 0), a finding that offers control over the surface chemistry of diazonium salts on Si. The dependence of the surface reaction kinetics on the crystal orientation was found to be directly related to differences in the potential of zero charge (PZC) of each crystal orientation, which in turn controls the adsorption of the diazonium cations prior to reduction. Another consequence of the effect of PZC on the adsorption of diazonium cations, is that molecules terminated by distal diazonium moieties form a compact film in less time and requires less reduction potentials compared to that formed from diazonium molecules terminated by only one diazo moiety. In addition, at higher concentrations of diazonium cations, the mechanism of electrochemical polymerization on the surface becomes PZC-controlled adsorption-dominated inner-sphere electron transfer while at lower concentrations, diffusion-based outer-sphere electron transfer dominates. These findings help understanding the electro-polymerization reaction of diazonium salts on Si en route towards an integrated molecular and Si electronics technology. © 2022 Elsevier Incen_AU
dc.description.sponsorshipThe authors thank the ARC for funding (DP190100735). We thank Essam Dief for assistance in the XPS analysis.en_AU
dc.format.mediumPrint-Electronicen_AU
dc.identifier.citationRahpeima, S., Le Brun, A., Raston, C. L., & Darwish, N. (2022). Electro-polymerization rates of diazonium salts are dependent on the crystal orientation of the surface. Journal of Colloid and Interface Science, 626, 985-994. doi:10.1016/j.jcis.2022.07.014en_AU
dc.identifier.issn0021-9797en_AU
dc.identifier.issn1095-7103en_AU
dc.identifier.journaltitleJournal of Colloid and Interface Scienceen_AU
dc.identifier.pagination985-994en_AU
dc.identifier.urihttp://dx.doi.org/10.1016/j.jcis.2022.07.014en_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15668en_AU
dc.identifier.volume626en_AU
dc.languageEnglishen_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectSaltsen_AU
dc.subjectSiliconen_AU
dc.subjectCrystalsen_AU
dc.subjectOrientationen_AU
dc.subjectPolymerizationen_AU
dc.subjectReaction kineticsen_AU
dc.subjectCationsen_AU
dc.subjectReagentsen_AU
dc.titleElectro-polymerization rates of diazonium salts are dependent on the crystal orientation of the surfaceen_AU
dc.typeJournal Articleen_AU
dcterms.dateAccepted2022-07-03en_AU
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