Stabilization of Supported Metal Nanoparticles Using an Ultrathin Porous Shell

Supported Pt nanoparticles (<2 nm) were stabilized by a highly porous, alumina nanofilm that was deposited on the Pt and its high surface area silica support. The alumina film with subnanometer thickness control resulted from thermal decomposition of an aluminum alkoxide layer that was deposited by molecular layer deposition (MLD). A catalyst with a porous ultrathin alumina layer was much more stable to calcination in air, even at 800 degrees C. The alumina-coated Pt nanoparticles were less catalytically active, most likely because of the small size of the pores in the alumina layer.