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Edge Plane Pyrolytic Graphite Electrode Covalently Modified with 2‐Anthraquinonyl Groups: Theory and Experiment
Author(s) -
Kozub Barbara R.,
Henstridge Martin C.,
BatchelorMcAuley Christopher,
Compton Richard G.
Publication year - 2011
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201100424
Subject(s) - pyrolytic carbon , graphite , highly oriented pyrolytic graphite , electron transfer , monolayer , electrode , adsorption , electrochemistry , chemistry , marcus theory , covalent bond , cyclic voltammetry , materials science , physics , nanotechnology , quantum mechanics , organic chemistry , pyrolysis , kinetics , reaction rate constant
An edge plane pyrolitic graphite (EPPG) electrode was modified by electrochemical reduction of anthraquinone‐2‐diazonium tetrafluoroborate (AQ2‐N 2 + BF 4 − ), giving an EPPG–AQ2‐modified electrode of a surface coverage below a monolayer. Cyclic voltammograms simulated using Marcus–Hush theory for 2 e − process assuming a uniform surface gave unrealistically low values of reorganisation energies, λ , for both electron transfer steps. Subsequently, two models of surface inhomogeneity based on Marcus–Hush theory were investigated: a distribution of formal potentials, E ′, and a distribution of electron tunneling distances, r 0 . The simulation of cyclic voltammograms involving the distribution of formal potentials showed a better fit than the simulation with the distribution of tunneling distances. Importantly the reorganization energies used for the simulation of E ′ distribution were similar to the literature values for adsorbed species.