Potential Dependent Infrared Absorption Spectroscopy of Adsorbed CO on Arc-melted Single Phase Pt, PtRu, PtOs, PtRuOs and Ru Electrodes

摘要

The potential and coverage dependent infrared absorption spectroscopy (IRAS) of linearly bound CO on single phase polycrystalline arc-melted P, PtRu(1/1), PtRu(8/2), PtOs(8/2), PtRuOs(8/1/1), PtRuOs(65/25/10), and Ru electrodes in 0.5 M H_2SO_4 are studied. The CO stretching frequencies decrease as the mole fraction of Pt in the alloy is decreased. The CO oxidation onset on pure Pt at 100.0% CO coverage is 0.5 V vs. a reversible hydrogen electrode and shifts negatively as the alloy mole fraction of Pt is reduced. At CO dosing conditions that yield 100% coverage on pure, Pt, the CO bandwidths increase with decreasing Pt mole fraction: on pure Pt the bandwidths increase as the CO coverage is reduced. The effect of CO coverage and bulk alloy composition on the Stark tuning rates (STRs) has been systematically examined on Pt, and a series of binary and ternary alloy surfaces. The systematic displacement, to lower frequencies, of the linear STRs as the mole fraction of Pt is reduced suggests no significant island formation when CO is adsorbed in the hydrogen region on the arc-melted alloy surfaces.