First-principles study of a new structure and oxidation mechanism of Pt3Zr

Abstract

Zirconia (ZrO2)-metal interfaces are interesting for solid oxide fuel cells. Although the oxidation of Pt3Zr provides a new route for the formation of ZrO2-Pt interfaces, the crystal structure of Pt3Zr remains controversial and the oxidation mechanism of Pt3Zr is unclear. To solve these problems, we use first-principles calculations to explore the crystal structure of Pt3Zr. We demonstrate a stable structure of Pt3Zr based on phonon dispersion. Importantly, two new Pt3Zr structures, Ti3Pt-type (Pm3m) and Fe3Al-type (Fm3m), are predicted. To study the oxidation mechanism, two possible doped models are considered. The calculated results show that the O atom prefers to occupy the tetrahedral interstitial site (TI) in comparison to the octahedral interstitial site (OI). We find that the oxidizing capacity of the Fe3Al-type cubic structure is stronger than that of other structures. In particular, we predict that Pt3Zr exhibits better oxidation capacity in comparison to other metals because of the strong localized hybridization between Zr and O.