Humidity dependence of the oxidation of carbon monoxide adsorbed on Pt/C and PtRu/C electrocatalysts

The oxidation of carbon monoxide adsorbed on a supported Pt (30 wt.% and 60 wt.% Pt/C) or PtRu (30 wt.% and 45 wt.% PtRu/C) gas diffusion electrode at various humidities and temperatures was investigated in an actual PEFC configuration. It is shown that the adsorbed CO-stripping potential on Pt/C and PtRu/C decreased with an increase in the humidity of the fuel until the dew point of the fuel reached the cell temperature. The CO-stripping potential of the 45 wt.% PtRu/C is lower and less sensitive to the humidity of the fuel than that of the 30 wt.% PtRu, which suggested that the PtRu/C with a higher catalyst density adsorbs water more strongly, even under lower humidity conditions.