Size-selective synthesis of immobilized copper oxide nanoclusters on silica

We report a straightforward route for preparing bulk quantities of size-controlled and low size dispersity copper oxide nanoclusters on amorphous silica. Adsorption of the copper–dendrimer complex on the silica surface minimizes aggregation, which results in previously unachieved low size dispersity of the nanoclusters. Copper oxide nanoclusters with mean diameters of 1–5 nm with size dispersities of only 8–15% were prepared by calcination of silica impregnated with Cu(II)–poly(propylene imine) dendrimer complexes of varying stoichiometry. The size and size distribution of the copper oxide nanoparticles are tunably controlled by the ratio of the Cu(II) to the terminal primary amines in the copper–dendrimer complex, DAB-Amn–Cu(II)x, the surface coverage of the DAB-Amn–Cu(II)x, and the impregnation procedure. This method is anticipated to be useful in the preparation of other metal oxide nanoparticles, e.g., Ni and Fe, and with other oxide substrates.