Effect of the support on the surface properties of ruthenium dioxide on silica glass

Abstract

The surface properties of SiO₂-supported RuO₂ have been found to depend on the temperature and the procedure of sample preparation. In particular, the point of zero charge in KNO₃ solutions has been observed to pass through a maximum at ca. 600 °C and then to drop at higher temperatures. Comparison with results obtained with RuO₂ powders and the surface analysis of supported RuO₂ by Auger electron spectroscopy have shown that substantial segregation of SiO₂ to the surface of RuO₂ takes place at temperatures higher than ca. 500 °C. These results suggest that caution should be used when interpreting data on the surface activity of SiO₂-supported oxides.