Effect of Competitive Adsorption at the Interface between Aqueous Electrolyte and Solid Electrode

At aqueous electrolyte-solid interfaces water molecules often need to be displaced to allow room for non-water adsorbates (molecules and ions) to access the solid surface. The displacement of water molecules requires an energy cost, which weakens the adsorption strength of non-water adsorbates. Such a process is referred to as competitive adsorption, and it is often overlooked in computational modeling, especially when static models are used to approximate the liquid water. Ab initio molecular dynamics simulations accurately describe the dynamic nature of liquid water and capture the competitive adsorption effect but require a significantly higher computational cost. We discuss how one can use molecular dynamics to study aqueous electrolyte-solid interfaces and ways in which a simple approximation can be developed to estimate the molecular dynamics simulation results. We highlight some of the interesting studies on competitive adsorption such as its dependency on electrostatic potential. There are only limited computational studies that sufficiently account for the competitive adsorption process. However, the number is expected to rise as there is an increasing effort to describe electrochemical reaction processes accurately.