Tuning the Electrochemical Interface of Ag/C Electrodes in Alkaline Media with Metallophthalocyanine Molecules

Abstract

Transition metal phthalocyanine (MPc) molecules were shown to be able to modify the electrochemical interface of the Ag catalyst in the alkaline electrolyte. Depending on the binding strength of the MPc (M = Fe, Co, Ni, and Mn) molecules with the OH– species, the electrochemically active sites of the Ag electrode surfaces can be altered accordingly. A structural model for illustrating the electrochemical interface of the Ag/C catalysts modified by the MPc molecules in alkaline media is proposed, which can be used to elucidate the ORR kinetics observed on various MPc@Ag/C catalysts in AEMFCs. The optimal CoPc–OH and Ag–CoPc interactions resulted in the highest kinetic current density and power density (536 mW cm–2 at 50 °C) observed with the AEMFCs using CoPc modified Ag/C cathode catalysts in comparison with the Ag/C and other MPc (M = Fe, Ni, and Mn) modified Ag/C catalysts .