Analysis\nof the OH Coverage on Low-Coordinated Pt\nSites at Low Potentials

In\na previous study, the presence of OH species adsorbed\non low-coordinated\nPt sites (or steps) at low potentials (the so-called hydrogen adsorption\nregion) using spectroscopy and electrochemical experiments was demonstrated.\nThis investigation was specifically conducted on a Pt(311) surface\nin an electrolyte with pH = 1. In this work, the study is extended\nto other surfaces featuring (111) terraces but with varying step geometry\nand step density. Additionally, the influence of the pH on these systems\nwas explored. Our findings reveal that the OH coverage on Pt steps\nat low potentials, measured just after the peak for the step, is independent\nof pH but sensitive to surface structure. Specifically, we have determined\nthat OH coverage is approximately 0.5 on surfaces with (110) steps\nand 0.33 on surfaces with (100) steps. Furthermore, the potential\nof zero total charge aligns with the local potential of zero charge\nfor the steps since it is predominantly influenced by adsorbed species\non these low-coordinated sites.