Characterization and Methanol Electrooxidation Studies of Pt(111)/Os Surfaces Prepared by Spontaneous Deposition

• DOI: 10.1021/la060164e
• Publication Date: 2006-08-12T09:02:03Z
• Authors: Christina M. John...; Svetlana Strbac; Adam Lewera; Eric Sibert; Andrzej Wieckowski
• Keywords: Deposition; Characterization

Catalytic activity of the Pt(111)/Os surface toward methanol electrooxidation was optimized by exploring a wide range Os coverage. Various methods analyses were used, including electroanalytical, STM, and XPS methods. The Pt(111) decorated with nanosized islands spontaneous deposition, coverage controlled changing exposure time to Os-containing electrolyte. structure deposits on characterized quantified in situ STM stripping voltammetry. We found that optimal for 0.7 +/- 0.1 ML, close 1.0 packing density. Apparently, high osmium provides more necessary oxygen-containing species (e.g., Os-OH) effective than surfaces lower (vs e.g., Ru-OH). Supporting evidence this conjecture comes from CO data, which show onset potential is lowered 0.53 0.45 V when increased 0.2 ML. However, decreases higher indicating Pt sites uncovered are sustaining significant oxidation rates. Furthermore, inactive platinum substrate absent: Au(111), bulk ingot, thick films electrodeposited Pt(111), all compare poorly Pt(111)/Os. conclude bifunctional mechanism applies similarly Pt(111)/Ru, although fewer available sites. Finally, window observed shift positively versus Pt(111)/Ru. Because difference Ru oxophilicity under electrochemical conditions, deposit species, at least below 0.5 vs RHE. Both potentials required provide sufficient number active removal site-blocking catalyst process occurs.