Surface modification of TiO2 photonic crystals by nanoscopic Fe oxides for enhanced visible light photocatalysis

Postgraduate Thesis uoadl:2876790 292 Read counter

Unit:
Κατεύθυνση Φυσική των Υλικών (ΒΑΣΙΚΗ ΦΥΣΙΚΗ)
Library of the School of Science
Deposit date:
2019-06-25
Year:
2019
Author:
Pylarinou Martha
Supervisors info:
Λυκοδήμος Βλάσης, Επίκουρος Καθηγητής, Τμήμα Φυσικής, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Γαρδέλης Σπυρίδων, Αναπληρωτής Καθηγητής, Τμήμα Φυσικής, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Τσακμακίδης Κοσμάς, Επίκουρος Καθηγητής, Τμήμα Φυσικής, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Original Title:
Επιφανειακή τροποποίηση φωτονικών κρυστάλλων TiO2 με νανοσκοπικά οξείδια Fe για ισχυρή φωτοκαταλυτική δράση στο ορατό
Languages:
English
Greek
Translated title:
Surface modification of TiO2 photonic crystals by nanoscopic Fe oxides for enhanced visible light photocatalysis
Summary:
In this work, controlled surface modification of TiO2 photonic crystals by “molecular” scale FeOx nanoclusters was applied for the first time using the chemisorption-calcination-cycle method of metal acetylacetonates on titania, in order to develop macro-mesoporous FeΟx-TiO2 photonic films with high photocatalytic activity under visible light. TiO2 inverse opals of variable photonic gap were fabricated using the successive evaporation- induced self-assembly and co-assembly of polymer colloidal spheres of three different diameters (220, 260 and 330 nm) with suitable alkoxide titania precursors. Photonic band gap engineering in the visible range was thereby implemented in combination with the optimization of the filmsmorphological characteristics investigated by scanning and transmission electron microscopy, Raman spectroscopy and specular and diffuse UV-Vis reflectance measurements. Controlled variation of the surface Fe oxide concentration was performed by successive chemisorption-calcination cycles of Fe(acac)3, while photocatalytic activity evaluation was carried out on the degradation of salicylic acid, a colorless water pollutant rarely investigated by photonic crystal photocatalysts, under UV-Vis and visible light
The obtained results showed that the deposition of low amounts of “molecular” scale FeOx nanoclusters on the nanocrystalline walls of TiO2 inverse opals leads to photocatalytic films with high performance on salicylic acid degradation under visible light, evading the loss of holes oxidizing ability that is usually observed in visible light active TiO2 photocatalysts. The observed enhancement was related to the synergy of slow photons and surface states induced by the strong interfacial coupling between titania and Fe oxides that causes the reduction of the electronic band gap. However, enhancement of the visible light electronic absorption by increasing the surface oxide loading competes with the photonic enhancement, especially under UV-Vis irradiation that is crucial for the photocatalytic degradation of colorless pollutants.
Main subject category:
Science
Keywords:
Photonic crystal, titanium dioxide, iron oxides, slow photons
Index:
Yes
Number of index pages:
1
Contains images:
Yes
Number of references:
47
Number of pages:
50
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