Spectroelectrochemical and electrical characterization of poly(cobalt-tetraaminophthalocyanine)-modified electrodes: electrocatalytic oxidation of hydrazine

Polymeric complex films of cobalt-tetraaminophthalocyanine (Co-TAPc) and te traaminophthalocyanine without the metallic center (H-2-TAPc) were grown po tentiodynamically on either glassy-carbon or conducting-glass electrodes. T he electrolyte used in the electropolymerization was a 0.1 M tetrabutylammo nium perchlorate-DMF solution containing the monomer. The modified electrod es were characterized by UV-Vis spectroscopy, voltammetry and electrochemic al impedance spectroscopy. The role of the Co(II) center and the performanc e of these polymeric electrodes as electrocatalysts for hydrazine oxidation in aqueous solutions of pH 13 are discussed. The results indicated that Co (II) is the species acting as the electronic receptor of hydrazine, thus en hancing the electrocatalytic effect of the poly(Co-TAPc) electrode. This wa s also confirmed by the charge transfer resistance values from electrochemi cal impedance spectroscopy obtained during hydrazine oxidation, i.e. about 6 x 10(3) Omega on the poly (H-2-TAPc) electrode and about 500 Omega on the poly(Co-TAPc) electrode. (C) 2000 Elsevier Science B.V. All rights reserve d.