Electrochemistry of Fe-Phenylenediamine Derived Cathode Catalysts Supported on Carbon

The primary goal of this work has been to better understand the oxygen reduction (ORR) activity of a series of Fe-N-C catalysts, formed by mixing Fe chloride with o-phenylenediamine (PDA) followed by heat treatment (HT). It is shown that, for HT at less than 500oC, significant redox chemistry, typical of a o-PDA redox polymer, is revealed in fully deaerated acidic solutions. This redox chemistry disappears at higher HT temperatures, arguing that the ORR active site arises from the thermal decomposition product of the PDA surface polymer. By electrodepositing PDA, either from a solution of o-PDA or from one also containing Fe3+, followed by ORR studies, it is demonstrated that the presence of Fe in the PDA film serves to enhance the ORR activity.