(Invited) Ag-TiO₂/Tiox Nanocomposites for Enhanced Photocatalysis

Sensitizing the surface of metal oxide semiconductors with plasmonic metal nanoparticles has been a prominent area of research in recent years. We report the growth of silver platelets on the surface of electrospun TiO2 and TiOx (white and black) nanofibers. Platelet geometry of silver is particularly attractive for maximizing absorption in the visible region. The tunable nature of the surface plasmon resonance (SPR) in the visible region, via changes in the particle size and shape of the metal nanoparticle, is the driving force behind its use in improving visible light harvesting in the plasmonic/metal-oxide nanocomposites for improved photo-degradation efficiency. We have chosen to explore the impact of silver platelet on the “black” titania since its Ti3+ defects have been shown to exhibit remarkable activity under visible irradiation offering a potential solution to the band gap limitations of TiO2 by introducing mid-gap energy states. Further enhancement of photocatalytic activity could occur by the introduction of plasmonic Ag to a reduced Ti3+ states within the black titania. UV/Visible spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy were used to confirm the presence of anisotropic Ag formation on the surface of the TiO2 as well as the oxygen vacancies (Ti3+) in the fibers. Resulting composite materials where then used in visible light photocatalytic testing against chemical threats using a solar simulator as the source of irradiation and monitored using various analytical techniques.