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Published on: October 18, 2018
Investigation of polypyrrole degradation using electrochemical impedance spectroscopy
L F Q P Marchesi1, F R Simões, L A Pocrifka
1Laboratório Interdisciplinar de Eletroquímica e Cerâmica, Centro Multidisciplinar para o Departamento de Química, Universidade Federal de São Carlos, Caixa Postal 676, CEP 13565-905 São Carlos, SP, Brazil.
Abstract:
In this paper, the electrochemical degradation of polypyrrole film was studied by means of overpotential application. The overpotential was 0.58 V versus SCE, and after every 5 min of application of 0.58 V, a cyclic voltammogram was recorded in the range of -0.7 to 0.5 V as well as an electrochemical impedance spectroscopy and electrochemical quartz crystal microbalance (EIS and EQCM). The main characteristic is the huge increase in the charge transfer resistance (r(ct)), which indicates that the insertion process of ions in the polymer matrix is hindered by the electrochemical degradation. Once the process of insertion is damaged, the number of intercalated ions in the matrix should decrease, which is expressed by the low-frequency capacitance, which is proportional to the number of intercalated ions in the polymeric matrix. The decrease of intercalated ions has an influence in the mass variation of the polymer film, which is confirmed by EQCM measurements.
