Models for the electrocatalysis of hydrogen evolution
Prof. P. Quaino
Fac. Ingenieria Quimica, Universidad Nacional de Litoral, Santa
Fe, Argentine
Institut für theoretische Chemie, Universität Ulm, Allemagne
Lundi 8 mars 2010, 11h00
A theory for electrocatalysis developed by Schmickler-Santos can be
combined with density-functional
theory in order to obtain free-energy surfaces for electrochemical
reactions. The combined theory is
applied to the first step in the hydrogen evolution reaction, which is
a proton transfer from an electrolyte
solution to a metal electrode. Explicit calculations have been
performed for five metals: Pt, Au, Ag, Cu,
and Cd. In accord with experimental findings we find a high activation
energy for Cd, medium values for
the coin metals, and on Pt the transfer occurs with little activation.
These results are explained in terms
of the position of the d band of these metals and their interactions
with the hydrogen 1s orbital as the
latter passes the Fermi level in the presence of the solvent.