CO oxidation at Pd(100): A first-principles constrained thermodynamics study

TL;DR

This study uses first-principles thermodynamics to analyze CO oxidation on Pd(100), revealing that a thin surface oxide is most stable under relevant conditions and the system is near a transition between oxidic and reduced states.

Contribution

It introduces a multiscale modeling approach linking density-functional theory with thermodynamics to study surface oxides on Pd(100) during CO oxidation.

Findings

Thin surface oxide is most stable under catalytic conditions.

System is close to a transition between oxidic and reduced states.

Surface composition varies with temperature and pressure.

Abstract

The possible formation of oxides or thin oxide films (surface oxides) on late transition metal surfaces is recently being recognized as an essential ingredient when aiming to understand catalytic oxidation reactions under technologically relevant gas phase conditions. Using the CO oxidation at Pd(100) as example, we investigate the composition and structure of this model catalyst surface over a wide range of (T,p)-conditions within a multiscale modeling approach where density-functional theory is linked to thermodynamics. The results show that under the catalytically most relevant gas phase conditions a thin surface oxide is the most stable "phase" and that the system is actually very close to a transition between this oxidic state and a reduced state in form of a CO covered Pd(100) surface.