Giant O2-Induced Photoluminescence Modulation in Hierarchical Titanium Dioxide Nanostructures

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• 作者：Deborah K. Pallotti ; Luca Passoni ; Felice Gesuele ; Pasqualino Maddalena ; Fabio Di Fonzo ; Stefano Lettieri
• 刊名：ACS Sensor
• 出版年：2017
• 出版时间：January 27, 2017
• 年：2017
• 卷：2
• 期：1
• 页码：61-68
• 全文大小：685K
• ISSN：2379-3694

文摘

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.