On the Formal Redox Potential of Oxygen Reduction Reaction at Iron Phthalocyanine/Graphene Composite Electrode in Alkaline Media

The redox reaction of iron phthalocyanine (FePc) combined with electrochemically-reduced graphene oxide (ER-GO) was investigated as a function of FePc fraction. A FePc/ER-GO/GC electrode was fabricated and the redox response of Fe3+/2+ couple was analyzed by cyclic voltammetry. The formal potential was observed to change with the FePc fraction, and the most positive value was obtained at the full monolayer coverage. The onset potential of oxygen reduction reaction at the fabricated electrode shifted linearly with the formal potential of FePc. Such a coverage-dependent potential shift was explained in terms of the electronic interaction between FePc and substrate graphene surface based on the X-ray photoelectron spectroscopy as well as the theoretical DFT calculation of a model adsorption system. (C) The Electrochemical Society of Japan, All rights reserved.