After making a cold weld by pressing two clean metal surfaces together, and gradually separating the two pieces, a metallic nanowire is formed, which is progressively thinning down to a single atom before the contact is lost. We show evidence that the radii of such nanowires are influenced by electronic shell filling effects, in analogy to electronic shell structure in metal clusters. A modulation of the shell effect, known as supershell structure, is clearly observed. For sodium and potassium at larger diameters there is a crossover to crystalline facets with shell-closings corresponding to the completion of an additional atomic layer. We conclude that a complete analogy exists between shell structure in metallic clusters and nanowires.

In this paper we describe an unusual electrochemical phenomenon, namely cathodic corrosion of platinum. We show that all existing models of cathodic corrosion are inconsistent with our experimental observations. Therefore, we present a new model of cathodic corrosion, which is based on the assumption that metal anions are formed at the electrode surface during the corrosion process. These anionic species function as precursors for the formation of the final product of cathodic corrosion - metal nanoparticles.

We demonstrate how cathodic corrosion in concentrated aqueous solutions enables one to prepare nanoparticles of various metals and metal alloys. Using various characterization methods we show that the composition of nanoparticles remains that of the starting material, and the resulting size distribution remains rather narrow. For the case of platinum we show how the size and possibly even the shape of the nanoparticles can be easily controlled by the parameters of corrosion. Finally, we discuss the advantages of using the nanoparticles prepared by cathodic corrosion for applications in (electro-)catalysis.