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Issue 17, 2015
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Amplified electron transfer at poly-ethylene-glycol (PEG) grafted electrodes

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“Amplified” electron transfer is observed purely based on electron transfer kinetic effects at modified carbon surfaces. An anodic attachment methodology is employed to modify the surface of glassy carbon or boron doped diamond electrodes with poly-ethylene glycols (PEGs) for polymerisation degrees of n = 4.5 to 9.1 (PEG200 to PEG400). Voltammetry and impedance data for aqueous Fe(CN)63−/4− suggest systematic PEG structure-dependent effects on the standard rate constant for heterogeneous electron transfer as a function of PEG deposition conditions and average polymer chain length. Tunnel distance coefficients are polymerisation degree dependent and estimated for shorter PEG chains, β = 0.17 Å−1 for aqueous Fe(CN)63−/4−, consistent with a diffuse water–PEG interface. In contrast, electron transfer to 1,1′-ferrocene-dimethanol (at 1 mM concentration) appears un-impeded by PEG grafts. Mediated or “amplified” electron transfer to Fe(CN)63−/4− based on the 1,1′-ferrocene-dimethanol redox shuttle is observed for both oxidation and reduction with estimated bimolecular rate constants for homogeneous electron transfer of kforward = 4 × 105 mol dm3 s−1 and kbackward = 1 × 105 mol dm3 s−1. Digital simulation analysis suggests an additional resistive component within the PEG graft double layer.

Graphical abstract: Amplified electron transfer at poly-ethylene-glycol (PEG) grafted electrodes

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The article was received on 02 Mar 2015, accepted on 26 Mar 2015 and first published on 02 Apr 2015

Article type: Paper
DOI: 10.1039/C5CP01244A
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Citation: Phys. Chem. Chem. Phys., 2015,17, 11260-11268

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    Amplified electron transfer at poly-ethylene-glycol (PEG) grafted electrodes

    C. E. Hotchen, I. J. Maybury, G. W. Nelson, J. S. Foord, P. Holdway and F. Marken, Phys. Chem. Chem. Phys., 2015, 17, 11260
    DOI: 10.1039/C5CP01244A

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