First-principles study of structures and processes at metallic electrodes

Recently, the operation of an atomic-scale quantum switch has been demonstrated, which is controlled by an external electrochemical voltage applied to an independent gate electric field [1]. Pb, Au and Ag are used as candidate materials for the quantum switches. Still, the atomic processes and principles underlying the operation of the switch are not clear yet. Structural changes of the metal-water interface and deposition/diffusion on the metal electrodes in the presence of an electric field might be the elementary processes that are most likely involved in the switching process. Hence, the self-diffusion and surface structures at the metal-water interface of Pb (Au and Ag) stepped surfaces have been studied using first-principles electronic structure calculations [2]. These studies show that diffusion across the steps is facilitated by the exchange mechanism. Furthermore, the influence of the presence of water on the properties of the metal electrodes will be discussed. [1] F.-Q. Xie, L. Nittler, Ch. Obermair, Th. Schimmel, Phys. Rev. Lett. 93, 128303 (2004). [2] X. Lin et al., Electrochim. Acta 140, 505-510 (2014).