Maintaining catalytic activity of Au/TiO2 during the storage at room temperature

The preferential oxidation of CO in a hydrogen-rich stream (PROX) at around room temperature was used to test the storage effect on catalytic activity of Au/TiO2. It is demonstrated in this study that indoor light is the main cause of the deactivation of the catalyst. UV–vis results suggest that the gold ions on the Au/TiO2 surface can be slowly reduced to gold metal during exposure to light; moreover, XPS detected a substantial drop in gold content on the TiO2 surface. However, Raman spectra reveal that the presence of nano-gold on the surface can weaken absorption from the anatase phase of TiO2, and exposure to the light during storage can further weaken absorption. Nevertheless, HRTEM has shown no apparent growth of gold particles on TiO2 under light. This study reveals that storing Au/TiO2 in a well defined dark environment under ambient conditions for as long as 5 months ensures that its catalytic activity in PROX remains that of the fresh sample.