CO ADSORPTION AND OXIDATION ON PT(111) ELECTRODES MODIFIED BY IRREVERSIBLY ADSORBED BISMUTH IN SULFURIC-ACID MEDIUM

CO adsorption and desorption (''stripping'') on Pt(111) electrodes modified by irreversibly adsorbed bismuth have been studied. The presence of CO adsorbed on the Bi-Pt(111) electrode modifies the redox peak of the adsorbed bismuth, suggesting the presence of a CO-Bi mixed adlayer. Using the CO stripping charge after appropriate correction, the values of CO coverage for the different bismuth coverages were calculated, as well as the proportions of linear and bridged-bonded CO. Unlike in UHV environments, the presence of bismuth on the surface favors the linear configuration of the adsorbed CO. At Theta(Bi) = 0.15, the CO population is almost entirely constituted linear CO, regardless of the CO coverage. Transient CO stripping demonstrates that the presence of bismuth on the surface enhances CO oxidation through bismuth-mediated oxygen transfer. (C) 1995 Academic Press, Inc.