Deactivation of poly(o-aminophenol) film electrodes under prolonged potentiodynamic cycling

R. TUCCERI

Melbourne

Congreso; Biosensors 2014. 24th Anniversary World Congress on Biosensors,; 2014

24th Anniversary World Congress on Biosensors

Poly(o-aminophenol) (POAP) synthesized in acidic medium is found to be a useful material to build electrochemical sensors and electrocatalysts [1-4]. Considering the interest in POAP synthesized in acid medium in both basic and applied research, no much attention has been paid to the decay of the electroactivity of POAP caused by its extensive use. The aim of the present work is to study how the conductivity of POAP, change with prolonged potentiodynamic potential cycling (PPPC).PPPC reduces strongly the conductivity of POAP films. This effect is called here deactivation. Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) were employed in this study. The attenuation of the voltammetric response of the polymer with the increase in the number of oxidation-reduction cycles allowed one to define a degree of deactivation. EIS was employed to obtain dependences of charge-transport and charge-transfer parameters on the degree of deactivation of the polymer. Impedance spectra of POAP films in contact with the supporting electrolyte solution were analyzed on the basis of a modified electron hopping model, which considers a protonation reaction. Two impedance quantities were obtained from this model: an effective diffusion coefficient (De) which decreases as the degree of deactivation increases and an interfacial resistance Rm|f related to the electron transfer across the metal/polymer interface. Rm|f increases as the degree of deactivation increases. POAP films maintain their conducting properties almost unaltered for about 500 potential cycles (-0.2 V < E < 0.3 V vs. SCE) at a scan rate of 0.010 V s-1. However, a loss of conductivity was observed as the number of potential cycles was extended beyond 500.