Anode Materials for Mitigating Hydrogen Starvation Effects in PEM Fuel Cells

Localized hydrogen starvation at a polymer electrolyte membrane (PEM) fuel cell anode can lead to the formation of local cells in the membrane electrode assembly, which cause performance degradation at the fuel cell cathode due to carbon corrosion. We propose using hydrogen spillover materials as a hydrogen reservoir in the fuel cell anode in order to compensate for any temporary proton deficit caused by local flooding of the anode channels. We tested composite electrodes containing TiO(2), WSi(2), and WO(3), and compared their behavior to that of commercial Pt/Vulcan XC-72 carbon (Pt/Vu) benchmark catalysts, using gas-diffusion electrodes in a 0.1 M HClO(4) solution and pellet electrodes in a 0.5 M H(2)SO(4) solution. While TiO(2) yields no benefits, both WSi(2) and WO(3) can significantly delay the voltage excursion of the gas-diffusion electrode into the oxygen evolution region upon the cessation of hydrogen flow. X-ray data indicate that the beneficial effect of WSi2 may be caused by WO(3), because we observed conversion of WSi(2) to WO(3) during voltage cycling, without a significant loss in the apparent hydrogen adsorption-desorption area. Electrodes with WO(3) yielded the best results, with a hydrogen storage charge higher by a factor of 6 than for the Pt/Vu benchmark. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3530796] All rights reserved.