Manganese Oxide Overlayers Promote CO Oxidation on Pt

The influence of manganese oxide on CO oxidation over Pt was investigated. Pt/Al₂O₃ catalysts were modified by the Atomic Layer Deposition (ALD) of MnOx with deposition before or after adding Pt and the results were compared to those with an unmodified Pt/Al₂O₃ catalyst. The addition of MnO_x improved the catalyst durability, mitigating the agglomeration of Pt particles after thermal aging at 1073 K. The addition of MnO_x also promoted CO oxidation rates by creating active Pt-MnO_x interfacial sites despite the fact that CO adsorption was suppressed after high-temperature calcination. Transmission electron microscopy (TEM) showed that Pt was uniformly covered by a thin film of MnO_x after calcination. The implications of these results with regard to understanding MnO_x promotion of Pt catalysts are discussed.