Coadsorption of Copper and Sulfate on Au(111) Electrodes: Monte Carlo Simulation of a Lattice-Gas Model

We report ground-state calculations and Monte Carlo simulations for a lattice-gas model of the underpotential deposition of copper on Au(111) in sulfate-containing electrolytes. In a potential range of approximately 100$\sim$150 mV, this system exhibits a $(\sqrt3\!\times\!\sqrt3)$ mixed phase with 2/3 monolayer (ML) copper and 1/3 ML sulfate. Our simulation results agree well with experimental results and with other theoretical work.