1. Multi-scale modeling of the evolution of oxygen phases on Pt surfaces under realistic reactive conditions Aravind Asthagiri, Chemical Engineering Department, University of Florida
1.44 Å
Platinum-based catalysts are used in several commercial applications and a fundamental understanding of their reactivity under oxygen-rich conditions is important to the design of next-generation catalysts. Currently, our understanding of the evolution of these oxygen phases is limited; in particular the atomic-scale processes that dictate the large-scale changes that occur in the transition from a bare metal surface to a 2D or 3D metal oxide phase. We have used density functional theory to identify a novel atomic-level mechanism for the initiation of oxidation on Pt(111). Instead of expected sources such as subsurface oxygen or step edges, we find that at surface coverages beyond 0.5 ML the O atoms induce the Pt atoms to buckle upwards (see figure) leading to the formation of a PtOx compound. The oxide continues to grow as a 1-D oxide chain. We are currently exploring the reactivity of these 1-D oxide chains to NO and CO oxidation.
STM Images
simulated
experiment
A novel buckled Pt oxide compound has been identified as the precursor to oxidation of Pt(111). The DFT predicted buckling is very close to the experimental value from STM images.