Thermodynamics is not enough — The case of the Volmer reaction on silver

Abstract

The energy of activation for the Volmer step of the hydrogen evolution reaction on silver electrodes is evaluated using our own theory of electrocatalysis. The reactivity at the hollow sites of the flat Ag(1 0 0) surface and the vicinal Ag(1 1 5) surface is compared. Although the adsorption energy calculated by Density Functional Theory is similar for both systems, we found a substantially higher value for the activation energy in the case of the (1 1 5) crystal orientation. Our analysis shows that other important factors, such as the electronic interactions between reactant and substrate at the transition state, play a decisive role. Thermodynamics is not enough to explain reactivity.