Interfacial Properties of Ultrathin-Film Metal Electrodes: Studies by Combined Electron Spectroscopy and Electrochemistry

摘要: A pair of studies investigating the deposition and surface chemical properties of ultrathin metal films were pursued:(i) Pt-Co alloys on Mo (110); and (ii) Pd on Pt (111). Experimental measurement was based on a combination of electron spectroscopy (low energy ion scattering spectroscopy, X-ray photoelectron spectroscopy, Auger electron spectroscopy, and low energy electron diffraction) and electrochemistry (voltage efficiency, voltammetry, and coulometry).Mixed-metal preparation of Pt-Co films by thermal vapor deposition (TVD) resulted in a thin-film binary alloy. Careful analysis revealed a substantial divergence between the composition at the interface and that in the interior. This outcome was observed for all compositions and allowed for the construction of a “surface phase diagram”. The proclivities of the alloys of preselected compositions towards enhanced catalysis of the oxygen-reduction reaction were assessed in terms of their voltage efficiencies, as manifested by the open-circuit potential (OCP) in O2-saturated dilute sulfuric acid electrolyte. The