Electrosorbed carbon monoxide monolayers on Pt(111).

Conference · Thu May 10 04:00:00 EDT 2007 · Electrochim. Acta

DOI:https://doi.org/10.1016/j.electacta.2007.01.070· OSTI ID:1000185

Chang, K -C; Menzel, A; Komanicky, V; You, H; Acad Sci, Slovakia Sci

We review structures of high-density CO monolayers on Pt(1 1 1) surfaces in CO-saturated electrolytes or in gaseous CO at near atmospheric pressure, using surface X-ray scattering (SXS) and scanning tunneling microscopy (STM). In electrolytes, we confirmed the well-known (2 x 2)-3CO and ({radical}19 x {radical}19)-13CO structures and were able to study the transition between them. For gas-phase studies, we were able to stabilize extremely well-ordered CO monolayers by emersion transfer from an electrochemical cell. We found that the hexagonal close-packed (2 x 2)-3CO structure is the equilibrium phase at room temperature in {approx}1 atm CO gas pressure. This commensurate (C) phase transforms continuously to an incommensurate (IC) phase at elevated temperature (a second-order phase transition). We also confirm that the ({radical}19 x {radical}19)-13CO structure is stable at lower CO partial pressure. This C phase transforms discontinuously to an IC phase (a first-order phase transition). A tentative phase diagram and a brief review of structure details of the (2 x 2)-3CO and ({radical}19 x {radical}19)-13CO phases will be presented.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1000185
• Report Number(s): ANL/MSD/CP-58590
• Conference Information: Journal Name: Electrochim. Acta Journal Issue: 18 Sp. Iss. ; May 10, 2007 Journal Volume: 52
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ATMOSPHERIC PRESSURE
CARBON MONOXIDE
ELECTROCHEMICAL CELLS
ELECTROLYTES
HETEROGENEOUS CATALYSIS
PARTIAL PRESSURE
PHASE DIAGRAMS
SCANNING TUNNELING MICROSCOPY
SCATTERING