Exploring the initial oxidation of Pt, Pt3Ni, Pt3Au (111) surfaces: a genetic algorithm based global optimization with density functional theory

Abstract

Noble metal alloys are one of the most commonly used heterogeneous catalysts. During many reactions, the surface composition and oxidation states of the noble metal alloy particles have been reported to be dynamic. This paper describes a density functional theory study to explore the initial oxidation stages of the Pt-based surfaces, which are widely-used catalysts in various clean energy conversion processes. By applying a genetic algorithm based global optimization, we identified new surface phases at relatively high O coverages, 1 ML and 3/2 ML, on Pt and Pt alloy (111) surfaces. The existence of O transforms the metallic surfaces, creating oxide skins with different morphology and composition. Metals with higher reducibility are pulled out to the outmost surface, to bind with O atoms. The lattice constant affects the binding strength of O atoms over certain oxide skins. Moreover, the strain effect plays a crucial role in the formation of oxide overlayers.