Blocking effects of poly(o-aminophenol) towards adsorption processes at a gold film surface. A comparison with its performance as biosensor and electrocatalyst material

R. TUCCERI

The Open Physical Chemistry Journal

Bentham Science Publishers (www.bentahm.org/open).

Año: 2009 vol. 3 p. 63 - 71

1874-0677

The aim of this work was to qualitatively analyze how the electrochemical response of ametal surface is modified when it is gradually coated by poly(o-aminophenol) (POAP).To this end the electrochemical response of a thin gold film electrode was firstly studiedin the presence of different adsorbates (perchlorate, sulfate and benzenesulfonate anionsand the macromolecule poly(vinyl imidazole)). Then, the gold film electrode wasgradually coated by POAP films of different thicknesses and again, its electrochemicalresponse in the presence of the same adsorbates was recorded. Cyclic Voltammetry andthe Surface Resistance technique were employed in this study. Also, SEM images onthe gold film surface coated by POAP films of different thicknesses are shown.Dependence of the resistance change of the gold film on the external electrolytecomposition at POAP thicknesses lower than 0.4 mC cm–2 was attributed to thediscontinuous character of the polymer thickness on the gold surface. For polymerthicknesses higher than 0.4 mC cm–2, the resistance response of the gold film becomesindependent of both the external electrolyte composition and POAP thickness. Thus,POAP thicknesses higher than 0.4 mC cm–2 seem to be compact enough at the metal|polymer interface to prevent the interaction of the species contained in the supportingelectrolyte with the gold film surface. This conclusion seems to be in agreement withSEM images. Although the SR technique does not detect changes at the metal film|POAP interface for POAP thicknesses within the range 0.4 mC cm–2 to 1.5 mC cm–2,SEM images show that the external morphology of POAP becomes porous for filmthicknesses higher than 0.8 mC cm–2. The observations reported in this work could beuseful for understanding more clearly the electrochemical performance of sensors andcatalysts based on poly(o-aminophenol).Keywords: poly(o-aminophenol) films, gold film electrode, surface resistance.