Fast track to nanomaterials: microwave assisted synthesis in ionic liquid media

Abstract

Herein we present a general approach to metal and metal oxide nanoparticles using simple metal salts as starting materials. The reducing agent can be delivered in the form of the anion incorporated into the metal precursor respectively ionic liquid. Exemplary we demonstrate the synthesis of Cu and Ag as well as ZnO and NiO nanoparticles generated either from acetate or carbonate salts. All particles are synthesised by microwave heating without the necessity of inert conditions. Two different types of ionic liquids have been used as reaction media – tetra-n-butylphosphonium acetate (n-Bu₄POAc) and 1-butyl-2,3-dimethylimidazolium N,N-bis(trifluoromethylsulfonyl)imid (bmmim NTf₂). In this case, the choice of the ionic liquid seems to have significant influence on the size, shape and dispersity of the synthesised particles. It is clearly shown that the acetate anion present in all reaction mixtures can act as an inexpensive and nontoxic reducing agent. The final products in solid, liquid and gaseous phase have been characterised by XRD, TEM, NMR, FT-IR and online gas-phase MS.