Electrocatalytic Properties of Au electrods modified by an underlayer of Pd.

M.F. JUAREZ; G. SOLDANO; H. GUESMI; F. TIELENS; E. SANTOS

Congreso; Materials Science Engineering MSE 2014: ?Young Researchers meet Professionals?; 2014

geometric, electronic and bifunctional mechanisms [1-3]. The activity of nano-alloys can greatly exceed that of the originalsingle metals, indicating that their properties are not the simply addition of them.Among all the bimetallic systems, the most appropriate for basic research are well-defined planar single crystals withwell-defined composition and geometrical arrangements. They can be used as model catalysts to understand at an atomiclevel the diverse factors that determine reactivity.In particular, gold - palladium based alloys, have been experimentally prepared and found to be good catalyst for diversereactions [4,5].Besides experimental and theoretical results indicate segregation of gold, resulting in (nearly) pure gold in the topmostlayers, diverse methods have been developed to produce bimetallic surface alloys [6-8]. The resulting systems are notnecessarily in thermodynamic equilibrium, but they are stable in their environment [3].In this work, we study the interaction of hydrogen with a bimetallic system consisting of a complete monolayer of Pdunderneath the top layer of Au(111). First, we investigate the stability of such system, and then the interaction withhydrogen when it approaches the surface and penetrates up to the second layer of the foreign atom. We analyse in detail theenergetics and the electronic interactions for the Volmer step of hydrogen evolution reaction (HER), and the furtherabsorption below the surface layer of gold. We combine DFT-based computational techniques with the theory ofelectrocatalysis developed in one of our groups [9,10].