Morphological changes in electrochemically deposited poly(3,4-ethylenedioxythiophene) films during overoxidation

Abstract

Electrochemical and morphological properties of thin poly(3,4-ethylenedioxy-thiophene) (PEDOT) films deposited on gold were investigated in aqueous sulfuric acid solutions. X-ray diffraction and electron microscopy were used for monitoring the morphological changes and structure evolution caused by overoxidation. The diffraction peaks of PEDOT became sharper and more intensive during the subsequent oxidation cycles. This indicates that besides the degradation of the PEDOT film, its crystallinity was gradually improved with increasing the number of oxidation cycles. These changes may result in the appearance of novel properties that may be advantageous for specific applications.

Structural changes during the overoxidation of electrochemically deposited poly(3,4-ethylenedioxythiophene) films

“…According to [34] overoxidized poly(3,4-ethylenedioxythiophene) film-modified screen-printed carbon electrodes exhibited superior sensitivity and selectivity to dopamine. However, the basis for the observed selectivity of overoxidized polymer films is not entirely clear [32,35,36].…”

The Electrochemical Degradation of Poly(3,4-ethylenedioxythiophene) Films Electrodeposited from Aqueous Solutions

“…Overoxidation of PEDOT films prepared electrochemically under "normal" conditions has been investigated in [22][23][24][25]. A series of cyclic voltammetric curves of Au|PEDOT|0.1 M sulfuric acid (aq.)…”

“…According to [38] overoxidized poly (3,4-ethylenedioxythiophene) film-modified screen-printed carbon electrodes exhibited superior sensitivity and selectivity to dopamine. However, the basis for the observed selectivity of overoxidized polymer films is still not entirely clear [24,36,39].…”

“…[21][22][23][24][25] that at sufficiently positive electrode potentials, degradation of the polymer occurs. That is, when the positive potential limit of the cyclic voltammogram (CV) is extended to the region in which the "overoxidation" of the polymer film takes place, an oxidation peak (without a corresponding reduction peak) appears in the CV.…”

“…[22,23,24] it has been shown that PEDOT films in modified electrodes undergo structural changes during the overoxidation (degradation) process. The most probable stages involved in the overoxidation/degradation process are: 1) Overoxidation results in stress 3 generation in the PEDOT film [26].…”