The Effect of Pt:Ru Ratio of Thermal Alloying PtRu Catalyst on CO-tolerance

概要

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Platinum-ruthenium catalysts of various Pt:Ru ratios were prepared by a newly developed three-step method for use as anodes in stationary polymer electrolyte fuel cells. As the first step, a well-dispersed platinum catalyst was prepared, and then ruthenium was deposited in the vicinity of the platinum particles by a chemical deposition method as the second step. As the final step, the Pt–Ru catalysts were heat-treated to obtain well-alloyed structures. The Pt–Ru catalysts prepared by this method showed good CO tolerance, even though the particle size was relatively large. The CO tolerance increased with increasing the ruthenium content, and the highest CO tolerance was obtained at Pt:Ru ratios in the range of 1:2 to 1:3. On air bleeding, the catalysts of a wider range of Pt:Ru ratios showed good CO tolerance. Potential sweep durability tests revealed that the stability of the Pt–Ru catalysts of Pt:Ru=1:1 against high potentials (1000 mV vs. RHE) was lower than that of the catalysts of Pt:Ru=1:1.5 and 1:2.