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 mod ified 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 adlaye r. Using the CO stripping charge after appropriate correction, the val ues of CO coverage for the different bismuth coverages were calculated , as well as the proportions of linear and bridged-bonded CO. Unlike i n UHV environments, the presence of bismuth on the surface favors the linear configuration of the adsorbed CO. At Theta(Bi) = 0.15, the CO p opulation 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.