Dumbbell-like Bifunctional Au−Fe3O4

Dumbbell-like Au−Fe3O4 nanoparticles are synthesized using decomposition of Fe(CO)5 on the surface of the Au nanoparticles followed by oxidation in 1-octadecene solvent. The size of the particles is tuned from 2 to 8 nm for Au and 4 nm to 20 nm for Fe3O4. The particles show the characteristic surface plasmon absorption of Au and the magnetic properties of Fe3O4 that are affected by the interactions between Au and Fe3O4. The dumbbell is formed through epitaxial growth of iron oxide on the Au seeds, and the growth can be affected by the polarity of the solvent, as the use of diphenyl ether results in flower-like Au−Fe3O4 nanoparticles. Nanocomposites containing two or more different nanoscale functionalities are attractive candidates for advanced nano-materials. With controlled structure and interface interactions, these nanocomposites can exhibit novel physical and chemi-cal properties that will be essential for future technological applications. Core/shell nanostructures1-3 and exchange-coupled magnetic nanocomposites4,5 are two well-known composite systems that have shown enhanced optical, magnetic, and catalytic properties compared to their indi