Bimetallic Ru–Cu Nanoparticles Synthesized in Ionic Liquids: Kinetically Controlled Size and Structure

We report a new synthesis of size-controlled bimetallic Ru-Cu nanoparticles (NPs) in ionic liquids using two organometallic precursors. Interestingly enough, upon mixing ruthenium and copper precursors, smaller bimetallic NPs (1.9-2.8 nm) are formed as compared to single metals (Cu: 5 nm; Ru: 4 nm) in a large range of copper molar fractions (vCu = 0.005-0.91). Surface and microscopy techniques evidence that NPs have metallic copper on the surface and crystalline hexagonal close- packed metallic ruthenium core. This structure is further assessed by the catalytic activity of the bimetallic NPs, showing that conversion of benzene in cyclohexane is reduced with increasing vCu.