Remarks on the Electrochemical Potential of Small Silver Clusters in Aqueous Solution

Abstract

AbstractSilver clusters in aqueous solutions containing excess Ag+ ions may be regarded as tiny metal‐electrodes. The electrochemical standard potentials of metal electrode equilibria Agn⇆Agn‐1 + Ag+ + e− are much more negative than that of the compact silver‐metal electrode. The potential generally strives toward the value of the compact electrode with increasing agglomeration n of the particles, although a strong oscillation occurs in the n = 1 to 3 range. The trend is opposite to the size dependence of the ionization potential in vacuo. The main factor determining the redox potential in solution is not the hydration of the clusters {as one may suppose at first sight} but the binding energy of a silver atom in a cluster. — The electrochemical potentials of equilibria of the type Agn⇆Agn + e− and Agn−⇆Agn + e− are also discussed. — It is pointed out that results from photoionization experiments on clusters in vacuo would importantly improve our present knowledge of the electrochemistry of clusters.