Aluminum Nanoparticle Synthesis by Reduction of Halides with Na/K

ABSTRACTSolutions or mixtures of aluminum halides AlX3 (X = Cl, Br, I) or aluminum halide alkoxide (ROAlX2; R= i-Pr, X = Cl, Br) are prepared in toluene, or pentamethyldiethylenetriamine (PMDETA) and treated with a slight excess of 50:50 (wt.) sodium potassium alloy (Na/K). Upon agitation, the reaction takes place slowly. The reaction appears to be limited by the deposition of insoluble products on the surface of the Na/K since sonication in an ordinary ultrasonic cleaner is necessary to bring the reaction to completion in several hours. Aluminum nanoparticles (NPs) and Na and K halides are formed, and soluble Al compounds, are also formed in some cases. Lithium powder is used instead of Na/K to reduce Al(N(SiMe3)2)3 to Al NPs. In an effort to passivate the surface of the Al particles to oxidation or hydrolysis, various agents are added either during the reaction or afterward. The products are characterized by SEM, XRD, NMR, and TEM, and the stability to water and air is evaluated.