Pt monolayer on Fe(001) catalyst for O2 Reduction: A first principles study

Abstract

The results of spin-polarized density functional theory calculations for O2 dissociative adsorption on Pt monolayer on Fe(001) (PtML/Fe(001)) structure are presented and are compared with that of Pt(OOl). The potential energy curves for the reaction of Pt with O2 as a function of O 2 center-of-mass distance from the platinum layer and 0-0 interatomic distance show that PTML/Fe(001) produces a combination of lower activation barrier for O2 dissociation and weaker O-atom binding which are both beneficial for a easier O2 dissociation to produce adsorbed O and for subsequent reactions of O with other surface species for O2 reduction process. Local density of states at Pt surface shows induced spin polarization on the Pt atomic layer characterized by dzz peak: at the Fermi level, in good agreement with experimental findings. Such effect increases unfilled dzz orbital on Pt surface modifying Pt electronic surface structure towards a favorable O2-Pt d interaction. Decrease in the magnetic moments of O and Pt atoms upon O adsorption indicates an antiparallel O unpaired electron spin alignment with Pt spin rendering consequent stabilization and a. lowering of energy cost to O2 activation. On the other hand, the weaker O binding reflects the stronger Pt-Fe interlayer bonding typical for such bimetallic systems. © 2007 The Surface Science Society of Japan.