This study describes a simple two-step approach to coat gold nanorods with a silica/titania shell. Gold nanorods with an
aspect ratio of 2.5 (L=48±2 and d=19±1) are synthesized by a silver-seed mediated growth approach according to our
previously reported procedure (Hunyadi Murph ACS Symposium Series, Volume 1064, Chapter 8, 2011, 127-163 and
reference herein). Gold nanorods are grown on pre-formed gold nano-seeds in the presence of surfactant,
cetyltrimethylammonium bromide (CTAB), and a small amount of silver ions. A bifunctional linker molecule which has
a thiol group at one end and a silane group at the other is used to derivatize gold nanorods. The silane group is
subsequently reacted with both sodium silicate and titanium isopropoxide to a silica/titania shell around the gold
nanorods. By fine tuning the reaction conditions, the silica/titania shell thickness can be controlled from ~5 to ~40nm.
The resulting nanomaterials are stable, amenable to scale up and can be isolated without core aggregation or
decomposition. These new materials have been characterized by scanning electron microscopy, energy dispersive X-ray
analysis, UV-Vis spectroscopy and dynamic light scattering analysis. Photocatalytic activity of Au-silica/titania
nanomaterials under visible and UV illumination is measured via degradation of a model dye, methyl orange (MO)
under visible and UV illumination. The results indicate a 3 fold improvement in the photocatalytic decomposition rate of
MO under visible illumination vs. UV illumination.