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 H 2 O 2 production rates, j (H 2 O 2 ), at the Pt/C catalysts were measured in a half cell with 0.1 M HClO 4 solution at 90 °C. It was demonstrated that the PEM degradation rate decreased with decreasing amount of adsorbed hydrogen atoms (H ad ) 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 (H 2 O 2 ), although this was accompanied by the disadvantage of decreased mass activity for the hydrogen oxidation reaction. We also found good correlations between the j (H 2 O 2 ) 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.