Modification of Cathode Catalyst to Improve PEFC Cell Performance under Low Relative Humidity

Abstract

Here we report several trials to modify cathode Pt catalysts to improve fuel cell performance under low relative humidity. First approach was to introduce hydrophilic group such as organic sulfonic group to Pt catalyst. The effect of the content of sulfur in cathode catalyst on the cell voltages at RH=31% was examined. Several samples of modified catalysts exhibited better cell voltages than the base catalyst. Nevertheless, the modified catalysts containing excess amount of organic sulfonic group exhibited lower cell voltage at dry condition. The cell voltages were different among the catalysts whose contents of sulfur were almost the same. It indicated that the condition other than the content of organic sulfonic group also affected the cell performance under the lower humidity.