Structural transformation process in underpotential monolayer adsorbates: Two types of adsorption sites on the electrode

A theory is proposed for the structural transformation process in monolayer adsorbates on surfaces with two types of adsorption sites. Several possibilities based on various combinations of the initial coverage of the adsorption sites by the adsorbate are discussed. The theoretical results are used for analyzing experimental data obtained with both quasi-perfect and real electrodes and it is found that the transformation process on these electrodes is describable in terms of adsorption sites along the step edges and on the terraces between the steps on the electrode surface.