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Anion adsorption on clean or copper modified Pt(111) and Rh(111) electrode surfaces studied by in-situ infrared reflection absorption spectroscopy

1994; Elsevier BV; Volume: 372; Issue: 1-2 Linguagem: Inglês

10.1016/0022-0728(94)03472-9

1873-2569

Yoshitaka Shingaya, M. Ito,

Catalytic Processes in Materials Science

Stepped Pt surfaces having different width (1 1 1) terraces interrupted by (1 1 0) or (1 0 0) monoatomic steps were employed to evaluate the catalytic activity toward CO oxidation at Pt specific sites in HClO4, H2SO4, and H3PO4 solutions, as well as in phosphate buffer and alkaline solution. The catalytic activity at the (1 1 1) terraces was sensitive to the nature of the anions derived from the electrolyte dissociation, while no effect on activity was detected at the monoatomic steps. A change in solution pH, passing from acid to alkaline solutions, had contrasting effects on catalytic activity at the (1 1 1) terraces and the step sites, with the catalytic activity of the (1 1 1) terraces improving, while activity at the step sites deteriorated. During the CO adlayer oxidation, the release of surface sites occurred preferentially from the (1 1 1) terraces of the Pt(s) − [(n − 1)(1 1 1) × (1 1 0)] surfaces, while from Pt(s) − [(n)(1 1 1) × (1 0 0)] surfaces, (1 1 1) terrace and (1 0 0) step sites were released simultaneously.