Interaction of OH radical with Pre-adsorbed Hydrogen on Pt (111) Surface: A DFT Study

MAURICIO ARCE; ELISABETH SANTOS; WOLFGANG SCHMICKLER; PAOLA QUAINO

Praga

Congreso; 63rd Annual Meeting of the International Society of Electrochemistry; 2012

International Society of Electrochemistry

The hydrogen electrode reaction (HER) is one of the most studied reactions, mainlybecause of its implications in the fuel cell technology; but in spite of all the knowledgegathered throughout the last decades, most of the work has focused the studies in acidicmedia, while alkaline electrolytes have not become attractive until recently.In this sense, the aim of the present work is to study the interaction between theadsorbed hydrogen (Had) on a Pt(111) surface with the OH radical in the framework ofDFT (density functional theory).To understand the influence of an alkaline media, the effect of OH radical on a pre-adsorbed Had/ Pt(111) electrode has been investigated. The surface was considered tobe covered with a submonolayer of pre-adsorbed hydrogen (Coverage Had = 1/9). To have a fullunderstanding about the interaction between the OH and Had, series of calculationswere performed in a way that either the H or OH were moved in z-coordinate with a0.2 A step. In each calculation the Pt surface was kept frozen as well as the z-coordinate of the adsorbed H and the O. A complete energetic, electronic andgeometric characterization was carried out.Our results show that the most stable situation, withoutconsidering water formation, is a H and OH co-adsorbed state where the OH is situatedon top at 2 A from the surface and the H is either in bridge or hollow site at 1 or 1.6 A,respectively. Water is formed only when the H radical is sufficiently far away from thesurface at 2.2 A.