Potential response of poly(o-aminophenol) film electrode to dissolved ferric ion

Pory(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 redox potential of PoAP was lower than that of the Fe3+/Fe2+ redox couple, and Fe3+ ions captured were partially reduced to form Fe2+ in the film electrode. The electrode showed a Nernstian response to dissolved ferric ions. Although the PoAP film electrode captured Zn2+, Ni2+ and Cu2+, it showed no potential response to the corresponding cations because the corresponding reduced forms (Zn, Ni, Cu) were absent in the film.