Abstract
We present two recent applications of lattice-gas modeling techniques to electrochemical adsorption on catalytically active metal substrates: urea on Pt(100) and (bi)sulfate on Rh(111). Both systems involve the specific adsorption of small molecules or ions on single-crystal electrodes, and they are characterized by a particularly good fit between the adsorbate geometry and the substrate structure. The close geometric fit facilitates the formation of ordered submonolayer adsorbate phases in a range of electrode potential positive of the range in which an adsorbed monolayer of hydrogen is stable. In both systems the ordered-phase region is separated from the adsorbed-hydrogen region by a phase transition, signalled in cyclic voltammograms by a sharp current peak. Based on data from in situ radiochemical surface concentration measurements, cyclic voltammetry, and scanning tunneling microscopy, and ex situ Auger electron spectroscopy and low-energy electron diffraction, we have developed specific lattice-gas models for the two systems. These models were studied by group-theoretical ground-state calculations and numerical Monte Carlo simulations, and effective lattice-gas interaction parameters were determined so as to provide agreement with the experimental results.
| Original language | English |
|---|---|
| Pages (from-to) | 389-400 |
| Number of pages | 12 |
| Journal | Surface Science |
| Volume | 335 |
| Issue number | C |
| DOIs | |
| State | Published - 20 Jul 1995 |
Keywords
- Chemisorption
- Computer simulations
- Construction and use of effective interatomic interactions
- Electrochemical methods
- Equilibrium thermodynamics and statistical mechanics
- Low index single crystal surfaces
- Solid-liquid interfaces
- Surface thermodynamics