INVESTIGATIONS OF COADSORPTION OF CARBON-MONOXIDE WITH S OR BI ADATOMS AT A PLATINUM-ELECTRODE BY IN-SITU FTIR SPECTROSCOPY AND QUANTUM-CHEMISTRY ANALYSIS

The adsorption of CO on a Pt electrode was used as a molecular probe, and the surface properties with respect to the electronic structure of the Pt electrocatalyst during modification by S or Bi adatoms were in vestigated by a combination of cyclic voltammetry, in-situ Fourier tra nsform IR (FTIR) spectroscopy and cluster model analysis using self-co nsistent charge discrete variational X(alpha) (SCC-DV-X(alpha)) calcul ations. It is found that the S adatom decreases the ability of the Pt surface to donate electrons. resulting in weakened CO adsorption and i ncreasing vibrational frequency of the C=O band of adsorbed CO molecul es. However, the opposite effects were observed in the case of Bi adat oms. The electronic and vibrational properties of the potential depend ence of CO adsorbed on a Pt electrode were also studied carefully. The results of quantum chemistry calculations are in good agreement with the experimental results of in-situ FTIR spectroscopy and also reveal the deeper significance of the IR spectroscopy data.