Fabrication of shape-controlled hematite particles and growth of gold nanoshells

Hematite particles with various morphologies including spherical- and spindle-shaped nanostructures were synthesized. Meanwhile, the self-assembly method, combined with the seeded growth technique, has been used to deposit gold nanoshells on the surface of spindle-shaped hematite. After Au nanoparticle coatings were obtained by the adsorption of small gold nanoparticles on hematite particles modified with 3-aminopropyltrimethoxysilane, gold ions are further reduced by formaldehyde and hydroxylamine, respectively, thicker and rough nanostructured Au nanoshells can be grown. The deposition process was monitored by TEM and UV–vis spectroscopy, showing a gradual change in the optical features of the colloids since the surface of hematite is more densely covered by Au nanoshell. Such particles with rough Au shells will offer advantages for SERS detection.