Atmospheric-pressure O2 plasma treatment of Au/TiO2 catalysts for CO oxidation

• Atmospheric-pressure O2 cold plasma is explored to treat Au/TiO2 catalyst.
• The plasma-treated catalyst exhibits higher activity than the calcined one.
• The plasma-treated catalyst has small particle size and narrow size distribution.
• The plasma-treated catalyst possesses plentiful low-coordinated Au species.

Atmospheric-pressure O2 plasma generated by dielectric barrier discharge (DBD) is applied to treat Au/TiO2 catalysts synthesized via the deposition–precipitation method for CO oxidation. The plasma-treated sample (S-P) presents a higher activity than the calcined one (S-C). To elucidate the plasma treatment effect, XPS, TEM/HRTEM, sub-ambient pulse CO chemisorption and in situ DRIFTS techniques were used for catalyst characterization. In comparison with S-C, TEM/HRTEM reveals that the S-P catalyst has small particle size and narrow size distribution; XPS and DRIFTS analyses indicate plentiful surface hydroxyl groups on S-P sample. Pulse CO chemisorption and in situ DRIFTS of CO adsorption show that significant increase of low-coordinated Au species has been achieved by the plasma treatment. The improved activity of S-P is ascribed to large amount of low-coordinated Au species and interface active sites as well as abundant surface hydroxyl groups.

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