In situ analysis of catalytically active Pd surfaces for CO oxidation with near ambient pressure XPS

• Recent studies on CO oxidation on Pd surfaces with NAP-XPS were reviewed.
• Catalytically active phases on the Pd surfaces were characterized.
• All the catalytically active phases include surface-segregated high-density oxygen.
• Reaction kinetics on the Pd surfaces under NAP and UHV conditions were compared.

X-ray photoelectron spectroscopy (XPS) is useful for in situ analysis of catalytically active surfaces under reaction conditions. We conducted in situ observations of CO oxidation on Pd single-crystal surfaces with different orientations under near ambient pressure (NAP) conditions with XPS. In this short review we compare catalytically active surfaces of Pd with the different orientations. Both surface oxides and atomic oxygen chemisorbed on metallic surfaces can be active for CO oxidation depending on surface geometric structure. We propose similarity between the surface oxides and the chemisorbed oxygen from a viewpoint of availability of active oxygen. Catalytic activity of the metallic surface under NAP condition is also compared with that under ultrahigh vacuum conditions.

In situ analysis for CO oxidation on Pd surfaces under near ambient pressure conditions with XPS and mass spectroscopy reveals catalytically active phases.Figure optionsDownload high-quality image (189 K)Download as PowerPoint slide