The kinetics of structural changes in anionic adlayers on stepped Au(111)s electrodes from sulfuric acid solutions

Abstract

AbstractThe kinetics of structural changes in anionic adlayers on stepped Au(111)s electrodes has been investigated in sulfuric acid solutions by potential step experiments. The experimental transients obtained with “quasi‐ideal” (miscut <0.5°) surfaces could be modelled with the exponential law of nucleation in combination with 2D surface diffusion‐controlled growth which is preceded by an adsorption process. The semi‐quantitative analysis was restricted to i vs. t‐traces, which revealed significantly different time constants of these two processes. The current transients with higher miscut angle showed (i) a systematic increase of the nucleation rate with increasing step density and (ii) a decrease of the macroscopically detectable charge density associated with the nucleation and growth process. The latter could be parameterized within a first approximation employing the general Avrami‐ansatz in combination with an adsorption process. In‐situ STM experiments showed that increasing step density of the substrate surface is accompanied with decreasing domain size of the ordered (√3 X √7) (hydrogen) sulfate adlayer patches. Respective correlations with the kinetic data obtained will be discussed.