Size-controlled synthesis of platinum nanoparticles supported on γ-Al2O3 and their thermal stability

Feasibility was demonstrated for the preparation of Pt/gamma-Al2O3 by precipitation of size-controlled platinum nanoparticles with narrow size distribution from colloidal solutions. The size and size distribution of the nanoparticles supported on gamma-Al2O3 were found to remain unchanged upon precipitation. X-ray phase analysis showed that platinum is oxidized to give PtO2 upon raising the sintering temperature from 120 to 300 A degrees C. The oxide formed is completely decomposed above 500 A degrees C. Marked enlargement of the supported nanoparticles occurs above 400 A degrees C. Aggregation along with increasing size of the nanoparticles is observed above 700 A degrees C.