Etude de l'interface de l'or polycristallin au contact de solutions aqueuses de perchlorate de potassium et d'acide perchlorique

Abstract

Differential capacity-potential curves at the interfaces gold-KClO 4 and gold-HClO 4 have been studied in a large range of concentration of the electrolytes. Zero charge potential has been determined by means of these curves; its value −0.040 V(SCE) ±0.010 is independent of concentration and pH, which means that there is no specific adsorption of ClO 4 − in this potential range. The electrical double layer model without specific adsorption accounts for capacity-potential curves for neutral and acidic solutions at concentrations lower than 5×10 −2 M. At positive charge densities, before classical oxide formation, the capacity-potential curves for acidic solutions show a region within which the surface begins to be covered by oxygen. The study of the influence of ClO 4 − concentrations C(E) curves in this region suggests that ClO 4 − ions are slightly specifically adsorbed at positive charge densities.