Cation capturing ability and the potential response of a poly(o-aminophenol) film electrode to dissolved ferric ions

Poly(o-aminophenol) (PoAP) film was electrodeposited on an indium-tin oxide electrode. The PoAP film electrode captured dissolved cations such as Fe3 because of the coordination ability of the film. The cation capturing abil ity was confirmed by the X-ray photoelectron spectroscopy and the cyclic vo ltammograms of the PoAP film. The redox potential of PoAP was lower than th at of the Fe3+/Fe2+ redox couple, and the Fe3+ ions captured in the film we re partially reduced to form Fe2+ ions. The PoAP film electrode had the Fe2 + ions, and the electrode showed a Nernstian potential response to dissolve d Fe3+ ions. The response time was less than 10 s, and the response was obs erved in the concentration range above 10(-5) M. Although the PoAP film ele ctrode captured Zn2+, Ni2+, and Cu2+, it showed no potential response to th e corresponding cations because the corresponding reduced forms (Zn, Ni, Cu ) were absent in the film. (C) 2001 The Electrochemical Society. All rights reserved.