The role of oxides in catalytic CO oxidation over Rhodium and Palladium

Johan Gustafson, Olivier Balmes, Chu Zhang, Mikhail Shipilin, Andreas Schaefer, Benjamin Hagman, Natalia M Martin, Per-Anders Carlsson, Maciej Jankowski, Ethan J. Crumlin, Edvin Lundgren, Lindsay Richard Merte

Index: 10.1021/acscatal.8b00498

Full Text: HTML

Abstract

Catalytic CO oxidation is a seemingly simple reaction between CO and O2 molecules, one of the reactions in automotive catalytic converters, and the fruit-fly reaction in model catalysis. Surprisingly, the phase responsible for the catalytic activity is still under debate, despite decades of investigations. We have performed a simple but yet conclusive study of single crystal Rh and Pd model catalysts, resolving this controversy. For Rh, the oxygen covered metallic surface is more active than the oxide, while for Pd, thin oxide films are at least as active as the metallic surface, but a thicker oxide is inactive. Apart from resolving a long-standing debate, our results are of great importance for oxidation catalysis in general and especially for avoiding extinction due to too high oxygen exposures.