Thermal stability of oxide-supported gold nanoparticles

In this study, we report on the influence of support and gas atmosphere on the thermal stability of Au nanoparticles on oxidic supports. All samples were prepared with a modified impregnation method and have initial Au particle sizes in the range of 3-4 nm. We observed that in air, Au nanoparticles on SiO2 and Al2O3 are thermally much more stable than Au nanoparticles on TiO2. For instance, upon treatment up to 700 degrees C, on SiO2, Au particles grew from 4 to 6 nm while on TiO2 from 3 to 13 nm. For Au nanoparticles on TiO2, growth is accelerated by oxidizing atmospheres and the presence of water and/or chloride. On non-reducible supports and in non-oxidizing atmosphere, the supported Au nanoparticles were remarkably stable. The insight into the growth of oxide-supported Au nanoparticles in reactive atmosphere offers an additional tool for a rational choice of a support for high-temperature gas-phase reactions involving gold nanocatalysts.