We demonstrate exceptionally large modulation of PL intensity in hierarchical titanium dioxide (TiO2) nanostructures exposed to molecular oxygen (O2). Optical responsivities up to about 1100% at 20% O2 concentrations are observed in hyperbranched anatase-phase hierarchical structures, outperforming those obtainable by commercial TiO2 nanopowders (up to a factor of ∼7 for response to synthetic air) and significantly improving the ones typically reported in PL-based opto-chemical gas sensing using MOXs. The improved PL response is discussed in terms of the specific morphology of hierarchical structures, characterized by simultaneous presence of small nanoparticles, large surface areas, and large voids. These characteristics guarantee an optimal interplay between photogenerated charges, PL-active centers, and adsorbed gas molecules. The results highlight the potentialities offered by hierarchical structures based on TiO2 or other MOXs and open interesting scenarios toward the development of all-optical and/or hybrid (opto/electrical) chemical sensors with improved sensitivity.

Giant O2-Induced Photoluminescence Modulation in Hierarchical Titanium Dioxide Nanostructures

PALLOTTI, DEBORAH KATIA;GESUELE, FELICE;MADDALENA, PASQUALINO;LETTIERI, STEFANO
2017

Abstract

We demonstrate exceptionally large modulation of PL intensity in hierarchical titanium dioxide (TiO2) nanostructures exposed to molecular oxygen (O2). Optical responsivities up to about 1100% at 20% O2 concentrations are observed in hyperbranched anatase-phase hierarchical structures, outperforming those obtainable by commercial TiO2 nanopowders (up to a factor of ∼7 for response to synthetic air) and significantly improving the ones typically reported in PL-based opto-chemical gas sensing using MOXs. The improved PL response is discussed in terms of the specific morphology of hierarchical structures, characterized by simultaneous presence of small nanoparticles, large surface areas, and large voids. These characteristics guarantee an optimal interplay between photogenerated charges, PL-active centers, and adsorbed gas molecules. The results highlight the potentialities offered by hierarchical structures based on TiO2 or other MOXs and open interesting scenarios toward the development of all-optical and/or hybrid (opto/electrical) chemical sensors with improved sensitivity.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/667073
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 32
  • ???jsp.display-item.citation.isi??? 30
social impact