MODIFIED GLASSY-CARBON ELECTRODES OBTAINED BY ELECTROCHEMICAL TREATMENT - EFFECTS ON THE HETEROGENEOUS ELECTRON-TRANSFER KINETICS OF AN ADSORBED AROMATIC AMINE
N. Vettorazzi et al., MODIFIED GLASSY-CARBON ELECTRODES OBTAINED BY ELECTROCHEMICAL TREATMENT - EFFECTS ON THE HETEROGENEOUS ELECTRON-TRANSFER KINETICS OF AN ADSORBED AROMATIC AMINE, Electrochimica acta, 44(2-3), 1998, pp. 345-352
Glassy carbon (GC) electrodes were modified by polishing and electroch
emical pre-treatment (ECP) in an acidic aqueous medium to obtain a rep
roducible kinetic response. The surface state was characterised by an
electrochemical parameter, eo, which has been demonstrated to be propo
rtional to the number of surface sites susceptible of oxidation. A pro
be molecule N,N,N',N'-tetramethyl- 1,1'-naphthidine (TMN) was adsorbed
on the modified GC by interacting with specific chemical sites. The a
mount of adsorbed TMN measured by cyclic (CV) and linear sweep voltamm
etry (LSV) varies linearly with eo. By using this relation, it is poss
ible to predict the degree of surface modification. An EE oxidation me
chanism was proposed for the adsorbed probe molecule and the kinetic c
onstants were calculated by a semiempirical method using experimental
data and the resolution of differential equations by use of Simnon(TM)
software. In addition, ECP does not change the electronic sites that
promote the electron transfer and the observed transfer rate constant
is riot affected by different degrees of electrochemical modification
(measured through Q(0) values). Thus, the procedure gives a reproducib
le modified GC\aqueous electrolyte interface for the electro-oxidation
of the probe molecule. (C) 1998 Published by Elsevier Science Ltd. Al
l rights reserved.