The Role of Ferromagnetic Substrate in the Reactivity of Pt/Fe Overlayer: A Density Functional Theory Study

Abstract

We investigated the energetics of O 2 reaction on a model bimetallic system, Pt bilayer on Fe(001), using six-dimensional potential-energy surface derived from spin-polarized density functional theory calculations. The model system renders same surface geometry and binding energy with the reference system, unresconstructed Pt(001), thus a systematic investigation on the role of Fe substrate was appropriately conducted. Results show that O 2 dissociation may proceed from a “no barrier” molecular adsorption on bridge with O–O axis lying parallel to the surface and spanning towards top sites ( t – b – t ) to translation towards four-fold hollow site ( b – h – b ) yielding dissociated O atoms on the bridge. In this reaction pathway, O 2 should overcome an activation barrier of ∼0.15 eV with respect to the initial state, which is comparable to that of the reference system (∼0.14 eV). However, the binding energy of O 2 with respect to its gas phase in all three states (initial, transition and final) is less as ...