CO tolerance of ordered intermetallic phases

The tolerance to CO poisoning of several ordered intermetallic compounds including PtPb, PtBi, Pt3Ti, Pt3Zr, Pt3Ta and Pt2Ta has been evaluated in terms of both peak potential and coulometric charge, and the results have been compared to polycrystalline Pt. In addition, in situ FT-IR has been employed to further characterize the interaction of CO with PtPb which has been one of the most promising materials. The propensity of these intermetallic phases to exhibit tolerance to CO poisoning is a function of both composition and structure, with materials with high Pt content exhibiting little or no improvement over Pt. PtBi exhibited virtual immunity to CO poisoning, whereas PtPb and Pt2Ta exhibited some poisoning by CO with stripping potentials less positive than bulk Pt. The adsorption of CO onto PtPb likely arises, at least in part, as a result of non-stoichiometries in the PtPb (with excess Pt) as it is not a congruently melting phase. The remaining materials with higher Pt content did not show any evidence of enhanced tolerance to CO poisoning when compared to pure Pt.