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Molecules 2018, 23(7), 1677; https://doi.org/10.3390/molecules23071677

Photonic Band Gap and Bactericide Performance of Amorphous Sol-Gel Titania: An Alternative to Crystalline TiO2

1
Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
2
CQE, Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal
3
Faculty of Sciences and Technology, Azores University, Ladeira da Mãe de Deus, 9501-855 Ponta Delgada, Portugal
4
Centre of Physics and Technological Research (CEFITEC), FCT/UNL Faculdade de Ciências e Tecnologia, 2829-516 Caparica, Portugal
*
Author to whom correspondence should be addressed.
Academic Editors: Ahmad Mehdi and Sébastien Clément
Received: 21 May 2018 / Revised: 2 July 2018 / Accepted: 6 July 2018 / Published: 10 July 2018
(This article belongs to the Special Issue Sol-Gel Chemistry. From Molecule to Functional Materials)
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Abstract

In addition to its traditional application in white pigments, nanocrystalline titania (TiO2) has optoelectronic and photocatalytic properties (strongly dependent on crystallinity, particle size, and surface structure) that grant this naturally occurring oxide new technological applications. Sol-gel is one of the most widely used methods to synthesize TiO2 films and NPs, but the products obtained (mostly oxy-hydrated amorphous phases) require severe heat-treatments to promote crystallization, in which control over size and shape is difficult to achieve. In this work, we obtained new photocatalytic materials based on amorphous titania and measured their electronic band gap. Two case studies are reported that show the enormous potential of amorphous titania as bactericide or photocatalyst. In the first, amorphous sol-gel TiO2 thin films doped with N (TiO2−xNx, x = 0.75) were designed to exhibit a photonic band gap in the visible region. The identification of Ti-O-N and N-Ti-O bindings was achieved by XPS. The photonic band gaps were found to be 3.18 eV for a-TiO2 and 2.99 eV for N-doped a-TiO2. In the second study, amorphous titania and amine-functionalized amorphous titania nanoparticles were synthetized using a novel base-catalysed sol-gel methodology. All the synthesized amorphous TiO2 nanoparticles exhibit bactericide performance (E. coli, ASTME 2149-13). View Full-Text
Keywords: amorphous-TiO2; photonic band-gap; bactericide; NPs; films; sol-gel; E. coli amorphous-TiO2; photonic band-gap; bactericide; NPs; films; sol-gel; E. coli
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Gonçalves, M.C.; Pereira, J.C.; Matos, J.C.; Vasconcelos, H.C. Photonic Band Gap and Bactericide Performance of Amorphous Sol-Gel Titania: An Alternative to Crystalline TiO2. Molecules 2018, 23, 1677.

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