Electrocatalysis on Stepped Surfaces

ANDRES RUDERMAN; FERNANDA JUAREZ; ELIZABETH SANTOS; MILAGROS AVILA

Workshop; Elementary reaction steps in electrocatalysis: Theory meets Experiment; 2016

It is well known that defects play an important role in determining the properties ofthe electrodes. Systematic investigations of stepped surfaces, which allow asystematic control of the density of defects, are important tools to understand themechanisms involved in electrochemical reactions of interest in electrocatalysis.We have studied the hydrogen evolution reaction (HER) and metal decoration ofstepped metal surfaces combining experiments and theory. On (11n) silver surfaces,current transients were measured in order to obtain the kinetic constants of the HER.From a theoretical point of view, this reaction was also studied by combining DensityFunctional Theory (DFT), Molecular Dynamics (MD), Kinetic Monte Carlo (KMC),and our Electrocatalysis Theory. Adsorption energies of H were calculated ondifferent sites, finding that the adsorption is stronger on the step than on the terraces.Activation barriers of the Volmer process were calculated for (100) and (115)surfaces. We found that the barrier is lower on the step, whereas on the terrace of the(115) it is larger than on the (100) flat surface.Finally, we have investigated the metal decoration with Cu, Pt, and Pd of the (332)gold surface. Similarly to hydrogen on vicinal silver surfaces, the adsorption isstronger on the steps. However, there is a larger barrier to overcome the steps, in thecase of the metals.