Inhibition of Oxide Formation on Aluminum Nanoparticles by Transition Metal Coating

Nanometer-sized aluminum powder was synthesized by thermal decomposition of an alane solution in the presence of a titanium catalyst under an inert atmosphere. The resulting material, formally devoid of an oxide layer, was used to reduce complexes of gold, nickel, palladium, and silver. The reduction process yielded materials that contained the transition metal at a level between 1 and 3 atom % on a metals basis, as determined by inductively coupled plasma atomic emission spectroscopy and energy dispersive spectroscopy. After exposure to air at ambient conditions, the transition metal treated aluminum materials were found to contain less aluminum oxide than an aluminum sample that was not treated with a transition metal. The nickel treated sample contained as much or more metallic aluminum as the untreated aluminum sample, indicating that the passivating layer in the nickel treated aluminum was highly efficient at protecting the underlying aluminum.