Anomalous Behavior of Ru for Catalytic Oxidation: A Theoretical Study of the Catalytic Reaction CO + 1/2 O_2 --> CO_2

TL;DR

This theoretical study uses density functional theory to analyze the high catalytic oxidation rate of CO on Ru(0001), highlighting the dominant Langmuir-Hinshelwood mechanism and the role of oxygen coverage.

Contribution

It provides a detailed computational analysis of the reaction pathways and energetics explaining the anomalously high oxidation rate on Ru(0001).

Findings

Reactions via adsorbed CO molecules dominate.

Weakly bound oxygen layer facilitates high reaction rate.

Scattering mechanisms may influence reaction pathways.

Abstract

Recent experiments revealed an anomalous dependence of carbon monoxide oxidation at Ru(0001) on oxygen pressure and a particularly high reaction rate. Below we report density functional theory calculations of the energetics and reaction pathways of the speculated mechanism. We will show that the exceptionally high rate is actuated by a weakly but nevertheless well bound (1x1) oxygen adsorbate layer. Furthermore it is found that reactions via scattering of gas-phase CO at the oxygen covered surface may play an important role. Our analysis reveals, however, that reactions via adsorbed CO molecules (the so-called Langmuir-Hinshelwood mechanism) dominate.