Pulsing for Enhanced CO Mitigation: Single Cell Performance

Improved CO tolerance in PEM fuel cells was achieved by periodically varying the anodic overvoltage to convert CO to CO2 directly on the anode. The conversion was controlled by a feedback control algorithm, which used current pulsing and time- varying flow rate parameters as the control variables. Single cell performance data was obtained with 1 and 3 percent CO in a synthetic reformate mixture at 50 C using conventional catalysts and a Nafion 115 membrane. Favorable comparisons are made to 20 ppm CO in H2 for conventional operation and to representative DMFC performance. Durability remains a challenge, but preliminary data with less degradation is presented.