Static and dynamic Monte Carlo simulations of Br electrodeposition on Ag(1 0 0)

We study the static and dynamic properties of bromine electrosorption onto single-crystal silver (1 0 0) electrodes by Monte Carlo (MC) simulation. At room temperature the system displays a second-order phase transition between a low-coverage disordered phase at more negative electrode potentials and a c(2×2) ordered phase with bromine coverage 1/2 at more positive potentials. We explore the phase diagram and demonstrate that the broad shoulder observed in room-temperature cyclic voltammograms is due to local fluctuations resembling ordered phases with coverage 1/4, which exist in the model at much lower temperatures. We construct a dynamic MC algorithm using a thermally activated stochastic barrier-hopping model for the microscopic dynamics. We use this algorithm to study the phase ordering and disordering processes following sudden potential steps between the disordered phase and the c(2×2) phase, and to study the sweep-rate dependence in simulated cyclic-voltammetry experiments.