A method to preparing suspensions of metal or metal alloy nanoparticles in an ionic liquid involves the physical vapor deposition of a metal or a mixture of metals onto an ionic liquid. The method can be modified by the introduction of a reagent during or after formation of the suspension to yield nanoparticles of a metal salt. The nanoparticles can be isolated from the suspension by the thermal decomposition of the ionic liquid under conditions where the decomposition products are gaseous.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 The present invention was developed under contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The U.S. Government has certain rights in the invention.