Titanium Oxide Nanotubes Decorated with Ruthenium Oxide Nanoparticles for Photodegradation of Malachite Green, Methylene Blue, and Indigo Carmine
Buford, Jonathan Daniel
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Titanium dioxide (TiO₂) is the most widely studied material for photodegradation of organic contaminants thanks to its activity as well as the abundance, low-cost, and multiple nanostructures (particles, rods, and tubes). TiO₂ nanotubes are of interest because of their high surface area and have been modified with many metal-based nanoparticles to increase photocatalytic activity. In this thesis TiO₂ nanotubes decorated with 1-5nm diameter ruthenium oxide (RuO₂) nanoparticles were investigated. TiO₂ nanotubes decorated with green ruthenium oxide nanoparticles were successfully synthesized. The interaction between the RuO₂ nanoparticles and TiO₂ nanotubes (TNTs) shifted the XPS Ti 2p3/2 peak spectra to a lower binding energy, supporting that the nanoparticles were bound to the TNTs. The RuO₂-decorated TNTs were tested as photocatalysts for the photodegradation of three dyes: malachite green (cationic dye), methylene blue (cationic dye), and indigo carmine (anionic dye). The malachite green and methylene blue dyes adsorbed well to the surface of the RuO₂-decorated TNTs and were degraded in 120 min and 240 min respectively. The indigo carmine dye did not display significant adsorption for the RuO₂-decorated TNTs, which had slower photodegradation than the bare TNTs, due to the anionic nature of the dye. The indigo carmine was only degraded to about 40% after 240 min. Overall the RuO₂ decorated TNTs performed best in cationic dyes where superior adsorption was displayed compared to the bare TNTs and previously reported RuO₂ decorated TiO₂ nanoparticles, but lower photodegradation rates were observed.