Electronic Parameters of Ag(I) Oxide Anodically Formed on the Ag–Pd System Alloys: The Role of Bulk Composition and Structural Disorder of the Surface

The anodic formation of silver oxide in 0.1 M KOH deaerated alkaline solution at the alloys of the Ag–Pd system, including those with increased structural surface disorder due to its preliminary anodic modification in 0.01 M HNO3 + 0.09 M KNO3 deaerated solution is studied. The anodic modification includes silver selective dissolution at potentials below the critical value, hence, not causing destruction of the alloy structure. As a result of the anodic modification, the alloy surface is depleted in silver, but enriched with structural defects, primarily vacancies, which leads to an increase in surface roughness and in the free energy of the system as a whole. The oxide formed anodically on such a surface is expected to change a number of parameters, primarily related to its structure and electronic structure. In this paper, the electronic parameters of Ag(I) oxide are considered, namely, the type and concentration of its structural defects, as well as the flat-band potential. The work is aimed at the determining of the electronic parameters of Ag(I) oxide anodically formed in 0.1 M KOH on the Ag–Pd system alloys with an atomic fraction of palladium from 0.05 to 0.30 and different levels of structural ordering of the surface. The surface roughness was found to increase by a factor of 3–17 in the process of anodic modification, depending on the alloy initial bulk composition. With the increasing of palladium concentration, the particle sizes of the anodically formed Ag(I) oxide increased slightly, and the particle number decreased. The concentration of donor defects in the structure of the Ag(I) oxide and its flat-band potential increased with increasing both palladium bulk content in the alloy and its structural surface disorder.