(509bn) Nanostructured TiO2 Cavitation Nuclei for Catalytic Degradation of Methylene Blue with Pulsed Ultrasound

Sonochemistry is the use of sound to nucleate bubbles (i.e., acoustic cavitation) that facilitate chemical reaction typically in aqueous media. These cavitation events create high energy microenvironments that are capable of pyrolysing water and generating light (sonoluminescence). It has been shown that photocatalysts activated by sonoluminescence can further enhance the production of reactive species. However, there is often a physical separation between the cavitation event and the photocatalyst, limiting the potential benefits of the photocatalyst. Here, we wish to report on our novel nanostructured titanium dioxide nanoparticles that act as both a nuclei for cavitation and a photocatalytic site. We also demonstrate that pulsed ultrasound induced acoustic cavitation from our nanoparticles resulted in the rapid degradation methylene blue at rates nearly three orders of magnitude faster than other titanium dioxide-based nanoparticles using conventional sonochemical methods. This rapid degradation was due to the elevated presence of hydroxyl radicals produced by the titanium dioxide. We also found that sonochemical degradation was proportional to the noise generated by cavitation from the titanium dioxide nanoparticles. Therefore our report indicates that by simply nanostructuring current photocatalysts to also be a nucleation site for acoustic cavitation may greatly enhance sonochemical reaction rates.