A study on composite PtRu(1:1)-PtSn(3:1) anode catalyst for PEMFC

Composite PtRu(1:1)/C-PtSn(3:1)/C catalyst layers with various geometries and loadings were designed for a proton exchange membrane fuel cell (PEMFC) anode to improve carbon monoxide (CO) tolerance of the conventional PtRu(1:1)/C catalyst. The idea was based on an experimental finding that the onset potential of the PtSn for CO oxidation was lower than that of the PtRu and the resultant expectation that there seemed to be a possibility of using the PtSn as a CO filter. The CO tolerance of the composite catalyst of each design was judged by the cell performance obtained through a single cell test using H2/CO gases of various CO concentrations and compared to that of the PtRu/C catalyst. The highest CO tolerance among the composite catalysts tested in this study was obtained for the one with geometry of double layers in the order of PtRu/C and PtSn/C from the electrolyte layer and with respective PtRu and PtSn loadings of 0.25 and 0.12 mg cm−2. The cell with this composite catalyst showed better performance than the one with the PtRu/C catalyst. When a H2/100 ppmCO gas was used as the fuel in the single cell test, the cell voltages were measured to be 0.49 and 0.44 V at a current density of 500 mA cm−2, respectively for the cell with the composite and PtRu/C catalyst.