Pascal Boulet
Professor
Title: From The Microscopic Theory of The Electrochemical Atomic Layer Deposition (EC-ALD) to Atomistic Simulations
Biography
Biography: Pascal Boulet
Abstract
The phenomenon of deposition of a monolayer amount of metal atoms onto a dissimilar, more noble metal electrode at a potential more anodic than expected from the Nernstian equilibrium potential was recognized about 70 years ago but it was not before 1974 that Kolb, Gerischer and Przasnyski explained theoretically this concept known as the underpotential deposition (UPD) DVupd. Using over 20 couples of metals these authors found that DVupd followed the simple, linear equation DVupd =½Df, where Df is the difference in work functions between the adsorbate and the substrate. For most of the metal couples investigated, the relation was verified. However, this seemingly oversimplified relation was soon after contradicted by Bewick and Thomas’ experiments on the deposition of Tl and Pb on Ag single crystal electrodes. Thenceforth, there has been tremendous works achieved by several authors to refine the microscopic understanding of the UPD process. These theoretical works were often accompanied by numerical simulation approaches at the atomistic level (Monte Carlo and kinetic Monte Carlo techniques) and quantum mechanical calculations. However, despite the increase of computer and softwares capabilities the models used in these studies cannot fully capture the whole complexity involved in the UPD process and simplified model systems had to be used. In this paper, we will review the microscopic theory of UPD and the results obtained from computational, atomistic approaches. We will show the assets but also the weaknesses, and the foreseeable improvements in particular in the realm of the density-functional theory.
