Impact of Pt-Loading and Carbon Support of Pt/C Anode Catalysts on Membrane Degradation Rate in Fuel Cells

Abstract

In order to clarify the effect of both the Pt-loading and carbon supports in various commercial Pt/C anode catalysts on the chemical degradation rate of polymer electrolyte membranes (PEMs) in fuel cells, the membrane lifetime and fluoride emission rate (FER) were examined in a single cell with an accelerated stress test (AST) at 90 °C, while the H2O2 production rates, j(H2O2), at the Pt/C catalysts were measured in a half cell with 0.1 M HClO4 solution at 90 °C. It was demonstrated that the PEM degradation rate decreased with decreasing amount of adsorbed hydrogen atoms (Had) at the Pt/C−PEM interface by lowering the Pt-loading and using a porous carbon support (locating Pt nanoparticles within pores). The use of a graphitized carbon black (GCB) support was found to be very effective to increase the lifetime due to it having the lowest j(H2O2), although this was accompanied by the disadvantage of decreased mass activity for the hydrogen oxidation reaction. We also found good correlations between the j(H2O2) measured in a half cell and FER, as well as lifetime in a single cell, so that the lifetime of the PEM can be estimated in a shorter time.