Excitation Wavelength- and Medium-Dependent Photoluminescence of Reduced Nanostructured TiO2 Films

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989592%3A15310%2F19%3A73594939" target="_blank" >RIV/61989592:15310/19:73594939 - isvavai.cz</a>

Výsledek na webu

<a href="https://pubs.acs.org/doi/10.1021/acs.jpcc.9b01727" target="_blank" >https://pubs.acs.org/doi/10.1021/acs.jpcc.9b01727</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acs.jpcc.9b01727" target="_blank" >10.1021/acs.jpcc.9b01727</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Excitation Wavelength- and Medium-Dependent Photoluminescence of Reduced Nanostructured TiO2 Films

Popis výsledku v původním jazyce

The performance of TiO2 nanomaterials in solar energy conversion applications can be tuned by means of thermal treatments in reducing atmospheres, which introduce defects (such as oxygen vacancies), allowing, for instance, a better charge transport or a higher photocatalytic activity. The characterization of these defects and the understanding of their role are pivotal to carefully engineer the properties of TiO2, and among various methods, they have been addressed by photoluminescence (PL) spectroscopy. A definitive framework to describe the PL properties of TiO2, however, is still lacking. In this work, we report on the PL of nanostructured anatase TiO2 thin films, annealed in different atmospheres (oxidizing and reducing), and consider the effects of different excitation energies and different surrounding media on their PL spectra. A broad PL signal centered around 1.8-2.0 eV is found for all the films with UV excitation in air and in vacuum, while the same measurements in ethanol lead to a blueshift and to intensity changes in the spectra. On the other hand, measurements with different sub-bandgap excitations show PL peaking at 1.8 eV, with an intensity trend only dependent on the thermal treatment and not on the surrounding medium. The results of PL spectroscopy, together with electron paramagnetic resonance spectroscopy, suggest the critical role of oxygen vacancies and Ti3+ ions as radiative recombination centers. The complex relationship between thermal treatments and PL data in the explored conditions is discussed, suggesting the importance of such investigations for a deeper understanding on the relationship between defects in TiO2 and photoactivity.

Název v anglickém jazyce

Excitation Wavelength- and Medium-Dependent Photoluminescence of Reduced Nanostructured TiO2 Films

Popis výsledku anglicky

The performance of TiO2 nanomaterials in solar energy conversion applications can be tuned by means of thermal treatments in reducing atmospheres, which introduce defects (such as oxygen vacancies), allowing, for instance, a better charge transport or a higher photocatalytic activity. The characterization of these defects and the understanding of their role are pivotal to carefully engineer the properties of TiO2, and among various methods, they have been addressed by photoluminescence (PL) spectroscopy. A definitive framework to describe the PL properties of TiO2, however, is still lacking. In this work, we report on the PL of nanostructured anatase TiO2 thin films, annealed in different atmospheres (oxidizing and reducing), and consider the effects of different excitation energies and different surrounding media on their PL spectra. A broad PL signal centered around 1.8-2.0 eV is found for all the films with UV excitation in air and in vacuum, while the same measurements in ethanol lead to a blueshift and to intensity changes in the spectra. On the other hand, measurements with different sub-bandgap excitations show PL peaking at 1.8 eV, with an intensity trend only dependent on the thermal treatment and not on the surrounding medium. The results of PL spectroscopy, together with electron paramagnetic resonance spectroscopy, suggest the critical role of oxygen vacancies and Ti3+ ions as radiative recombination centers. The complex relationship between thermal treatments and PL data in the explored conditions is discussed, suggesting the importance of such investigations for a deeper understanding on the relationship between defects in TiO2 and photoactivity.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10403 - Physical chemistry

Projekt

<a href="/cs/project/EF15_003%2F0000416" target="_blank" >EF15_003/0000416: Pokročilé hybridní nanostruktury pro aplikaci v obnovitelných zdrojích energie</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Physical Chemistry C

ISSN

1932-7447

e-ISSN

—

Svazek periodika

123

Číslo periodika v rámci svazku

17

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

12

Strana od-do

11292-11303

Kód UT WoS článku

000466988600062

EID výsledku v databázi Scopus

2-s2.0-85065318607