Synthesis and Microstructure of Porous Aluminum and Intermetallic Nanomaterials

Abstract

ABSTRACTA series of porous aluminum-based materials are prepared by the reduction of solutions of metal chlorides with lithium powder in diethyl ether under dry argon. The reactants must be combined slowly, but either order of addition is used. The reduction of AlCl3 produces hollow Al balls composed of ~100 nm aluminum particles in nearly quantitative yield after the LiCl byproduct is washed away with dry tetrahydrofuran. Similar structures are formed when mixtures of AlCl3 and SiCl4, are reduced, except that the second component has the effect of reducing the Al nanoparticle size. Mixtures of AlCl3 with FeCl3 reduce to similar ball-like porous structures that are composed of Al, Fe, and Fe-Al intermetallic nanoparticles. When AlCl3 and ZnCl2 are co-reduced, flake-like nanoporous structures are obtained, and solutions of AlCl3 + VCl3 produce more compact nanoporous structures. Some side reactions involving ether cleavage that produces aluminum alkoxides and alkyls do occur, and the amount of side reaction is dependent on the identity of the second metal. The reduction of AlCl3 with excess (4 eq) Li powder produces LiAl nanomaterials. NMR shows the intermetallic compound LiAl to be the only Li-Al intermetallic present.