Synthesis of naked plasmonic/magnetic Au/Fe3O4 nanostructures by plasmon-driven anti-replacement reaction.

In this study, naked Au(core)/Fe3O4(shell) hybrid nanostructures are rapidly synthesized by a plasmon-driven anti-replacement reaction. The Au nanoparticles are prepared by pulsed laser ablation in water. The mixture of Au nanoparticles and FeCl3 solution is irradiated under a laser with a specific wavelength. The Fe3+ ions are reduced to low valence species by the 'hot electrons' in Au, and form the Fe3O4 spindles on the surface of Au nanoparticles. The Au nanoparticles are synchronously oxidized to Au+ and Au3+ ions by the 'hot holes'. The saturation magnetization and coercivity of Fe3O4 spindles are 48.7 emu g-1 and 218.9 Oe, respectively. Our work provides a facile route to obtain the naked Au/Fe3O4 plasmonic/magnetic nanostructures.