Increasing Proton Exchange Membrane Fuel Cell Catalyst Effectiveness Through Sputter Deposition

Sputterdeposition has been investigated as a tool for manufacturing proton-exchangemembrane fuel cell (PEMFC) electrodes with improved performance and catalystutilization vs. ink-based electrodes. Sputter-depositing a single layer of Pton the gas diffusion layer provided better performance (0.28 A/cm2at 0.6 V) than sputtering the Pt directly onto aNafion membrane (0.065 A/cm2 at 0.6 V) and equaled theperformance of the baseline for an equivalent Pt loading. Sputter-depositingalternating layers of Pt and Nafion-carbon ink (NCI) onto themembrane did not increase the performance over the baseline asmeasured in amperes per centimeter squared due to the excessivethickness of the NCI (the NCI accounted for 99.9% ofthe electrode thickness). However, three and six layer Pt/NCI membraneelectrode assemblies (MEAs) resulted in Pt activities double that ofthe 905 A/g at 0.6 V achieved by the ink-basedbaseline. Decreasing the thickness of each NCI layer increased theperformance of the six-layered Pt/NCI MEA from 0.132 to 0.170A/cm2 at 0.6 V, providing an activity of 2650 A/gat 0.6 V. It is likely that by further decreasingthe ratio of NCI to Pt in these electrodes, Ptactivity, and PEMFC electrode performance can be increased. ©2002 TheElectrochemical Society. All rights reserved.