Role of pH in the Formation of Structurally Stable and Catalytically Active TiO2-Supported Gold Catalysts
We report the investigation of titania (Degussa P25) supported gold catalysts prepared by magnetron sputtering. Catalysts grown on natural fumed titania were structurally unstable, resulting in the rapid coarsening of 2.4 nm gold clusters into large 20 nm gold clusters in a few days at room temperature under normal atmospheric conditions. However, treating the titania support powder to a mock deposition-precipitation process, at pH 4, followed by the subsequent deposition of gold onto this treated powder produced a remarkable enhancement in gold particle stability and a 20-fold enhancement of catalytic activity. Furthermore, it was found that treating the titania under basic conditions (pH 10) resulted in a further enhancement of structural stability and a further doubling of the reaction rate to 0.28 mol of CO/mol of Au s. This enhancement cannot be attributed to removing surface Cl- species from the titania, the formation of oxygen vacancies on the TiO2 surface, or an electronic effect. Instead, it appears to be associated with the formation of strongly bound hydroxyl species on the TiO2 surface. The formation of surface hydroxyls during the deposition-precipitation method is coincidental and contributes significantly to the properties of Au/TiO2 catalysts
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 980441
- Report Number(s):
- BNL-93359-2010-JA; TRN: US201015%%1826
- Journal Information:
- Journal of Physical Chemistry C, Vol. 113, Issue 1; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- English
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