Origin of the high activity of Au/FeOx for low-temperature CO oxidation: Direct evidence for a redox mechanism

FeOx-supported gold nanocatalyst is one of the most active catalysts for low-temperature CO oxidation. However, the origin of the high activity is still in debate. In this work, using a combination of surface-sensitive in situ FT-IR, Raman spectroscopy, and microcalorimetry, we provide unambiguous evidence that the surface lattice oxygen of the FeOx support participates directly in the low-temperature CO oxidation, and the reaction proceeds mainly through a redox mechanism. Both the presence of gold and the ferrihydrite nature of the FeOx support promote the redox activity greatly. Calcination treatment has a detrimental effect on the redox activity of the Au/FeOx, which in turn decreases greatly the activity for low-temperature CO oxidation. The gold-assisted redox mechanism was also extended to other metal-supported FeOx catalysts, demonstrating the key role of the FeOx support in catalyzing the CO oxidation reaction.

In situ spectroscopy techniques provide unambiguous evidence that the surface lattice oxygen of the iron oxide support participates directly in low-temperature CO oxidation over an Au/FeOx catalyst via an Fe3+ ↔ Fe2+ redox mechanism.Figure optionsDownload high-quality image (100 K)Download as PowerPoint slideHighlights
► The redox between Fe3+ and Fe2+ in CO oxidation was observed by in situ spectroscopy.
► The CO oxidation over Au/FeOx proceeds mainly via the redox mechanism.
► The presence of gold promotes greatly the redox activity between Fe3+ and Fe2+.
► Calcination had a detrimental effect on the redox activity.
► The redox mechanism works well on FeOx-supported other metal catalysts.