Characterization of modified solid electrodes with organized thin films of a tetra-substituted zinc phthalocyanine

Abstract

Organized thin films of a zinc phthalocyanine have been deposited on solid electrodes using several techniques, such as drop casting, immersion and Langmuir-Blodgett (LB), at several conditions, and their electrochemical response has been studied by cyclic voltammetry and differential pulse voltammetry. Topographical images by Atomic Force Microscopy reveal that the structure of immersion and LB films is uniform, showing granular aggregates and continuous layers, respectively. The electrochemical response of both kind of films is similar and shows peaks that can be correlated with redox processes occurring in the phthalocyanine ring. Drop casting films present a different topography, with rod-like structures, and the voltammograms show an enhancement in the peaks at positive potentials, which has been attributed to the influence of the atmospheric oxygen adsorbed during the film deposition. Immersion and LB films have also shown an increase in the oxidation current intensity of the voltammetric response after exposition to molecular oxygen. These results point to a possible application of these organized t-BuZnPc thin films as electrochemical oxygen sensors.