The nature of the Pt(111)/α-Fe2O3(0001) interfaces revealed by DFT calculations.

Abstract

Density functional theory calculations are performed to give a thorough description of structural, energetic, and electronic properties of Pt(111)/α-Fe2O3(0001) systems by spin-polarized calculations, accounting for the on-site Coulomb interaction. Toward the better understanding of Pt(111)/α-Fe2O3(0001) interfaces, two terminations of α-Fe2O3(0001) surface, namely, the single Fe- and the O3-termination, are considered and coupled with the four possible (top, hcp, fcc, and bridge) sites on Pt(111). The effect of the strain on clean hematite surfaces due to the lattice mismatch between the substrate and the overlayer is included in the analysis. Among the possible adsorption configurations, bridge sites are unstable, while the most favorable configurations are the ones at hollow sites. The stability of the interfaces is not only influenced by the termination of the overlayer but also influenced by the degree of its structural relaxation and the relative position of the first layer of O atoms in hematite with respect to Pt. To elucidate the different nature of the two terminations of the overlayer on Pt, projected density of states and 3D charge density difference plots are also discussed.