First insights of the electrocatalytical properties of stepped silver electrodes for the hydrogen evolution reaction

E. SANTOS; M. F. JUAREZ; A. RUDERMAN

Praga

Congreso; XIII International Conference on Electrified Interfaces; 2013

The electrocatalytic properties of vicinal Ag(11n) surfaces for the hydrogen evolution reaction are investigated. An analysis of the reactivity as a function of the step density is performed. The rate constants for Volmer and Heyrovsky steps are evaluated from potentiostatic transients. A correlation between the anisotropy of hydrogen adsorption energy for different sites with the non-linear dependence on the step density is established. We have shown that on stepped silver surfaces the rate of both the Volmer and the Heyrovsky reaction is faster on the steps than on the terraces. However, the rates of these reactions do not vary linearly with the step density. Our DFT calculations indicate that the adsorption energy at the step sites is independent of the terrace width, while the adsorption on the terrace sites depends both on the position along the terrace and the terrace length. Adsorption on shorter terraces is less favourable, and this explains the non-linear dependence of the rate on the step density. The distribution of the adsorption energies on the surfaces is quite complicated. A quantitative analysis requires a detailed kinetic modelling, for which this work has laid the foundations.