a lAutolab type III electrochemical
analyzer controlled with the GPES 4.9 software (EcoChemie, The
Netherlands). All SW voltammograms were smoothed using a Savicky
and Golay algorithm and baseline-corrected by the moving
average method (peak width of 0.01 V), using the GPES software.
A three-electrode cell system was used: a BDD working electrode
(Windsor Scientific Ltd.; Ø: 3 mm, diameter), a Pt-wire auxiliary
electrode, and an Ag/AgCl (3 mol L1 NaCl) (Model RE-1, BAS,
USA) reference electrode to which all electrode potentials hereinafter
are referred. The pH values of solutions were measured using a
WTW inoLab pH 720 meter with a combined electrode (glass-reference
electrodes).