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(001). The potential energy curves for the reaction of Pt with O2 as a function of O2 center-of-mass distance from the platinum layer and O-O 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.

Theoretical study for magnetic effect in dissociative adsorption of oxygen to a platinum monolayer on Ni(110) surface

“…The activation barrier (E a ¼ 0.51 eV) for this system is almost the same as the case of Pt/Fe(001) (E a ¼ 0.51 eV) [4]. Both are less than half of the case at barrier a clean Pt(001) surface (E a ¼ 1.2 eV).…”

“…The r and Z for final state (r ¼ 2.6 Ǻ, Z ¼ 1.0 Ǻ) of this system are almost same as that for final state (r ¼ 2.6 Ǻ, Z ¼ 1.10 Ǻ) of O 2 dissociative adsorption on Pt/Fe(001). The binding energy of oxygen with surface (i.e., potential energy at the final state) is À0.77 eV which is 80% bigger than the case of Pt/Fe(001) (À0.43 eV) [4]. Oxygen binds stronger on this surface than on Pt/Fe(001) surface.…”

“…In one of their next studies using DFT based first principles calculations, they have shown that on the MgeH dissociation of MgH 2 , Sc and Ni have the highest catalytic activities among the 3d transition metals (SceZn) [3]. In their another study, they have shown that Pt monolayer on Fe(001) surface (Pt/Fe(001)) can be magnetized resulting to a reduction of activation barrier in O 2 dissociative adsorption in half [4] as compared to the case of bare platinum surface [5]. So as a next step, it is of importance to study how another magnetic material Ni influences this reaction by the same calculation method mentioned above.…”

Pt monolayer on Fe(001) as an alternative cathode catalyst: a first principles study

“…The activation barrier of O 2 is 0.70 eV, just nearly half that of clean Pt (001), i.e. 1.2 eV, [11] and the O adsorbed binding is lower (0.43 eV vs 0.54 eV in Pt(001)). We rationalize the observed easier O 2 dissociation in Pt ML We therefore found a stronger Pt-Fe interlayer binding than that of Pt's corresponding pure metal slab.…”

First Principles Investigation for H2 Dissociative Adsorption on Ni and Cr-Decorated Ni Surfaces - An Application to Alkaline Polymer Electrolyte Fuel Cell

“…On the other hand, multilayer and heterogeneous catalysis have attracted interests in electronic structure engineering due to considerable number of applications and enhanced properties of the resulting material as compared to the parent metals. As a matter of fact, several stud- ies have proven that formation of bimetallic surfaces produces large perturbations and changes in the electronic, chemical and catalytic properties of the entire system as compared to the characteristics and properties of the parent metals [12][13][14].…”