Band structure calculations of Pt and Pt3Ti

Abstract

Linearized Augmented Plane Wave (LAPW) calculations of the Pt and Pt3Ti bulk electron structures are presented. We emphasis on hybridization, charge transfer effects and the impact on chemisorption properties Densities of States (DOS) and novel band-structures are also provided. The delocalized character of free electron states documents itself by sp-orbitals largely unaffected by alloy formation i.e. the Pt and Ti projected sp-densities are similar and also akin to the distribution of sp-states for pure platinum. The strong Pt-Ti interaction comes from d and f orbitals with a significantly lowered Pt d center-of-mass for the alloy and an intense Ti d structure above the Fermi level. The f-projected density of states gives two narrow peaks: a Ti peak below the Fermi level and an unoccupied Pt peak near Ef. Together the d and f interactions result in a much lowered DOS(Ef). Our results are of direct relevance for adsorption systems modelling titania supported platinum, a well known catalyst for CO hydrogenation. The ordered alloy, Pt3Ti, forms in the industrial catalyst under reducing conditions at elevated temperatures, a phenomenon related to the Strong Metal Support Interaction (SMSI) effect in catalysis, and much work has addressed special adsorption sites for enhanced methanation rates.