PNNL

Abstract

The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. In this paper, we describe and apply an ab initio quantum-mechanical model to examine the electrochemical dissociation of water over a number of close-packed and near-close-packed metal surfaces. We have examined a series of metals important for electrochemical energy generation and corrosion-resistant alloy development including Ni, Cu, Ru, Au, Mo, Pd, and Pt. Advances in electrochemical theory depend on a detailed understanding of the interplay between surface chemistry and electrochemical phenomena. Herein, we have used ab initio quantum-mechanical methods to examine the double-layer regions for H2O over these metals and compare the equilibrium potentials for the initial steps of water reduction and oxidation at the surface with known experimental quantities. We find that in its current form, the model developed herein is semiquantitative: it allows for the correct prediction of trends and the size of the double-layer regions, but in some cases it results in significant deviation with known absolute equilibrium potentials. Additional discussion is provided that outlines steps that may be taken to improve the quantitative accuracy of this model.