Ag Nanoparticle
Embedded TiO<sub>2</sub> Composite
Nanorod Arrays Fabricated by Oblique Angle Deposition: Toward Plasmonic
Photocatalysis
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Abstract
Using a unique oblique angle co-deposition
technique, well-aligned arrays of Ag nanoparticle
embedded TiO<sub>2</sub> composite nanorods have been fabricated with
different concentrations of Ag. The structural, optical, and photocatalytic
properties of the composite nanostructures are investigated using
a variety of experimental techniques and compared with those of pure
TiO<sub>2</sub> nanorods fabricated similarly. Ag nanoparticles are
formed in the composite nanorods, which increase the visible light
absorbance due to localized surface plasmon resonance. The Ag concentrations
and the annealing conditions are found to affect the size and the
density of Ag nanoparticles and their optical properties. The Ag nanoparticle
embedded TiO<sub>2</sub> nanostructures exhibit enhanced photocatalytic
activity compared to pure TiO<sub>2</sub> under visible- or UV-light
illumination. Ag plays different roles in assisting the photocatalysis
with different light sources. Ag can be excited and can inject electrons
to TiO<sub>2</sub>, working as an electron donor under visible light.
While under UV illumination, Ag acts as an electron acceptor to trap
the photogenerated electrons in TiO<sub>2</sub>. Due to the opposite
electron transfer direction under UV and visible light, the presence
of Ag may not result in a greater enhancement in the photocatalytic
performance