Role of terrace/step edge sites in CO adsorption/oxidation on a polycrystalline Pt electrode studied by in situ ATR-FTIR method

ATR-FTIRAS measurements combined with linear potential sweep voltammetry were conducted to perform detailed analysis of CO adsorption/oxidation processes on a chemically deposited Pt film on Si ATR prism. Roles of terrace and step edge sites were clearly demonstrated based on the band analyses of the atop, CO(L), and bridge bonded CO, CO(B), spectra during the adsorption/oxidation processes. In the main current peak region above 0.45 V, a direct spectroscopic evidence was obtained to show oxidation of CO(L) and its diffusion to the step edge sites, where local coverage of CO(L) and CO(B) increases between 0.5 V and 0.64 V. This triggers further oxidation of the overall CO adlayer.