We first apply the CIP approach to study the pristine and oxygen-covered Au(111) surfaces at different potentials and surfaces charges. Oxygen adsorption presents a typical electrochemical inner-sphere reaction, where a metal electrode strongly interacts with an adsorbate. The density of states (DOS) analysis in Figure shows that the electronic states of oxygen-covered Au(111) at and near Fermi level have significant contributions from goldoxygen interactions. This means that E DF T f is not independent of the presence of adsorbed oxygen and that the electrode potential might not be uniquely determined by the gold bulk.