Date of Graduation

Summer 2014

Degree

Master of Science in Materials Science

Department

Physics, Astronomy and Materials Science

Committee Chair

Robert Mayanovic

Keywords

nanocrystalline, nanoparticles, photoluminescence, adsorption, doping, Raman spectroscopy, photocatalysis, structure, hydrothermal treatment

Subject Categories

Materials Science and Engineering

Abstract

Photocatalysis is potentially a useful means of conversion of solar energy to the production of hydrogen fuel from splitting of water. Although several metal oxides have been shown to have photocatalytic activity, most are limited because of their inefficiency. In order to use metal-oxide-based materials as photocatalysts, it is necessary to increase their efficiency. The use of noble metals, either through doping or co-deposition, has shown promise for increasing the overall efficiency of metal-oxide-based nanomaterials. Using hydrothermal methods, I precipitated Rh on the surface of Cr2O3 nanocrystallites and within chromium oxide thin films. The Rh surface-doped Cr2O3 nanoparticles were prepared in water at temperatures up to ~220 °;C. Surface doping of nanophase materials with noble metals such as Rh has advantages in a more efficient use of a rare commodity and, in this case, is shown to cause greater structural phase stability of the nanoparticles than using bulk doping. Raman spectroscopy showed that the E1 g mode occurring at 276 cm-1 for Cr2O3 nanoparticles is shifted to 281 cm-1 for Rh surface-doped Cr2O3 nanoparticles. The photoluminescence of the Rh surface-doped Cr2O3 nanoparticles in the visible range (~450 – 650 nm) is significantly enhanced relative to that of Cr2O3 nanoparticles, suggesting that surface precipitation of Rh may cause more efficient photocatalytic activity of the Cr2O3 nanomaterial. My results show that Rh doped chromium oxide thin films grown using pulsed laser deposition methods are composed of multiple phases.

Copyright

© Lukmon O. Aminu

Campus Only

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