INIFTA   05425
INSTITUTO DE INVESTIGACIONES FISICO-QUIMICAS TEORICAS Y APLICADAS
Unidad Ejecutora - UE
artículos
Título:
Effect of the bathing electrolyte on the charge-transport process at poly(o-aminophenol)-modified electrodes. An ac impedance study in sulfate and benzenesulfonate solutions
Autor/es:
R. TUCCERI
Revista:
The Open Physical Chemistry Journal
Editorial:
Bentham Science Publishers (http://benthamscience.com/open/topcj/openaccess2.htm).
Referencias:
Lugar: Sharjah, U.A.E.; Año: 2010 vol. 4 p. 29 - 35
ISSN:
1874-0677
Resumen:
<!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:none; mso-layout-grid-align:none; text-autospace:none; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> The aim of this work was to study how charge-transport and charge-transfer processes at poly(o-aminophenol) film electrodes depend on the type and concentration of the external electrolyte solution in contact with the polymer film. To this end ac impedance measurements on poly(o-aminophenol) films contacting solutions of different anions such as sulfate and benzenesulfonate were carried out. These two different anions were chosen due to their differences in size and adsorbability. Impedance data were interpreted on the basis of a modified electron-hopping model, where the electron-transport rate within the polymer phase and the electron-transfer rate across the metal½polymer interface are represented by an effective diffusion coefficient (D) and a standard electrochemical rate constant (ksh), respectively. It was found that both parameters are independent of the type and concentration of the electrolyte solution within the thickness range from 10 nm to 35 nm. However, these transport parameters depend strongly on both external variables within the thickness range from 38 nm to 70 nm. In this regard, the rate of charge conduction through thick poly(o-aminophenol) increases with the increase of the concentration of the electrolyte solution. The increase of poly(o-aminophenol) conductivity with the increase of  film thickness was attributed to changes in the polymer morphology. It was assumed that the electrolyte incorporated into the open structure of a thick film reduces repulsive interactions between redox sites yielding a more compact distribution of redox centers as compared with that present in a thin film that does not incorporate the electrolyte. Lower distances between adjacent redox sites in a thick film facilitate the electron-hopping process, which in turn leads to a higher conductivity as compared with that of a thin film.