Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5357339 | Applied Surface Science | 2015 | 8 Pages |
Abstract
Titanium dioxide is one of the most important materials today in terms of green technology. In this work, we synthesis ultra-small titanium dioxide nanoparticles (NPs) via a two step process involving infrared laser ablation of a bulk titanium target in DDI water and subsequent irradiation of the colloidal solution with visible light. The as-prepared NPs contain defect states related to oxygen vacancies which lead to visible light sensitization as observed by photodegradation of methylene blue. Irradiation of the colloidal TiO2 solution, with a 532Â nm picosecond laser, lead to fragmentation and ultimate formation of ultra-small (<3Â nm) anatase particles. Shadowgraph was utilized to capture shockwave and cavitation bubble propagation during both the ablation and fragmentation processes. High-frequency ripples within the primary shockwave are identified as coming from laser induced stress-wave reflections within the metal target. A blueshift of the bandgap, for the ultra-small NPs, is explained by quantum confinement effects and rationalized using the Brus model.
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Authors
M. Amin, J. Tomko, J.J. Naddeo, R. Jimenez, D.M. Bubb, M. Steiner, J. Fitz-Gerald, S.M. O'Malley,