Solvothermal Synthesis, Gas-Sensing Properties, and Solar Cell-Aided Investigation of TiO2-MoOx Nanocrystals

Year: 2017

Authors: Epifani M., Kaciulis S., Mezzi A., Altamura D., Giannini C., Tang PY., Morante JR., Arbiol J., Siciliano P., Comini E., Concina I.

Autors Affiliation: CNR, IMM, Via Monteroni, I-73100 Lecce, Italy; CNR, ISMN, POB 10, I-00015 Rome, Italy; CNR, IC, Via Giovanni Amendola 122-O, I-70126 Bari, Italy; CSIC, Catalan Inst Nanosci & Nanotechnol ICN2, Campus UAB, Barcelona 08193, Spain; BIST, Campus UAB, Barcelona 08193, Spain; Catalonia Inst Energy Res IREC, Jardins Dones Negre 1, Barcelona 08930, Catalonia, Spain; ICREA, Pg Lluis Co 23, Barcelona 08010, Catalonia, Spain; Brescia Univ, Dept Informat Engn, Via Valotti 9, I-25133 Brescia, Italy; Brescia Univ, SENSOR, Via Branze 38, I-25123 Brescia, Italy; CNR, INO, Via Branze 38, I-25123 Brescia, Italy; Lulea Univ Technol, Dept Engn Sci & Math, S-97198 Lulea, Sweden.

Abstract: Titania anatase nanocrystals were prepared by sol-gel/solvothermal synthesis in oleic acid at 250 degrees C, and modified by co-reaction with Mo chloroalkoxide, aimed at investigating the effects on gas-sensing properties induced by tailored nanocrystals surface modification with ultra-thin layers of MoOx species. For the lowest Mo concentration, only anatase nanocrystals were obtained, surface modified by a disordered ultra-thin layer of mainly octahedral Mo-VI oxide species. For larger Mo concentrations, early MoO2 phase segregation occurred. Upon heat treatment up to 500 degrees C, the sample with the lowest Mo concentration did not feature any Mo oxide phase segregation, and the surface Mo layer was converted to dense octahedral Mo-VI oxide. At larger Mo concentrations all segregated MoO2 was converted to MoO3. The two different materials typologies, depending on the Mo concentration, were used for processing gas-sensing devices and tested toward acetone and carbon monoxide, which gave a greatly enhanced response, for all Mo concentrations, to acetone (two orders of magnitude) and carbon monoxide with respect to pure TiO2. For the lowest Mo concentration, dye-sensitized solar cells were also prepared to investigate the influence of anatase surface modification on the electrical transport properties, which showed that the charge transport mainly occurred in the ultra-thin MoOx surface layer.

Journal/Review: CHEMNANOMAT

Volume: 3 (11)      Pages from: 798  to: 807

More Information: The authors acknowledge CSIC/CNR project 2010IT0001 (SYNCAMON) and the SOLAR project DM19447. I. Concina acknowledges VINNOVA under the VINNMER Marie Curie Incoming Grant for partial funding (project Light Energy, LiEn, 2015-01513). We would like to thank Dr. Peiman Soltani for the XPS data collection, Mr. Giovanni Battista Pace for the help with the sample preparation, Mr. Giuseppe Chita for the XRD data collection, Mr. Nicola Poli for his assistance with the sensing measurements. We also acknowledge funding from Generalitat de Catalunya 2014 SGR 1638 and the Spanish MINECO coordinated projects between IREC and ICN2 TNT-FUELS and e-TNT (MAT2014-59961-C2-2-R). ICN2 acknowledges support from the Severo Ochoa Program (MINECO, Grant SEV-2013-0295). Part of the present work has been performed in the framework of Universitat Autonoma de Barcelona Materials Science PhD program.
KeyWords: nanocrystals; nanomaterials; sensors; solar cells; surface chemistry
DOI: 10.1002/cnma.201700160

Citations: 2
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