Colloidal Counterpart of the TiO2-Supported V2O5 System: A Case Study of Oxide-on-Oxide Deposition by Wet Chemical Techniques. Synthesis, Vanadium Speciation, and Gas-Sensing Enhancement

Year: 2013

Authors: Epifani M., Dnaz R., Force C., Comini E., Andreu T., Zamani RR., Arbiol J., Siciliano P., Faglia G., Morante JR.

Autors Affiliation: CNR, IMM, I-73100 Lecce, Italy; IMDEA Energy Inst, Electrochem Proc Unit, Mostoles 28935, Spain; Univ Rey Juan Carlos, Ctr Apoyo Tecnol, NMR Unit, Mostoles 28933, Spain; Univ Brescia, Dept Informat Engn, SENSOR Lab, I-25133 Brescia, Italy; CNR, INO, I-25133 Brescia, Italy; IREC, Barcelona 08930, Spain; CSIC, ICMAB, Inst Ciencia Mat Barcelona, Bellaterra 08193, Spain; ICREA, Barcelona 08010, Cat, Spain; Univ Barcelona, Dept Elect, XaRMAE, M2E,IN2UB, E-08028 Barcelona, Spain.

Abstract: TiO2 anatase nanocrystals were surface modified by deposition of V(V) species. The starting amorphous TiO2 nanoparticles were prepared by hydrolytic processing of TiCl4-derived solutions. A V-containing solution, prepared from methanolysis of VCl4, was added to the TiO2 suspension before a solvothermal crystallization step in oleic acid. The resulting materials were characterized by X-ray diffraction, transmission electron microscopy (TEM), Fourier transform infrared, Raman, and magic angle spinning solid-state V-51 nuclear magnetic resonance spectroscopy (MAS NMR). It was shown that in the as-prepared nanocrystals V was deposited onto the surface, forming Ti-O-V bonds. After heat treatment at 400 degrees C, TEM/electron energy loss spectroscopy and MAS NMR showed that V was partially inserted in the anatase lattice, while the surface was covered with a denser V-O-V network. After heating at 500 degrees C, V2O5 phase separation occurred, further evidenced by thermal analyses. The 400 degrees C nanocrystals had a mean size of about 5 nm, proving the successful synthesis of the colloidal counterpart of the well-known TiO2-V2O5 catalytic system. Hence, and also due to the complete elimination of organic residuals, this sample was used for processing chemoresistive devices. Ethanol was used as a test gas, and the results showed the beneficial effect of the V surface modification of anatase, with a response improvement up to almost 2 orders of magnitude with respect to pure TiO2. Moreover, simple comparison of the temperature dependence of the response clearly evidenced the catalytic effect of V addition.

Journal/Review: JOURNAL OF PHYSICAL CHEMISTRY C

Volume: 117 (40)      Pages from: 20697  to: 20705

More Information: Authors acknowledge CSIC/CNR project 2010IT0001 (SYN-CAMON). This work was partially supported by the SOLAR project DM19447 and the Spanish Government projects Consolider Ingenio 2010 C5D2009 00013 IMAGINE and CSD2009 00050 MULTICAT. J.A. acknowledges the funding from the Spanish MICINN project MAT2010-15138 (CO-PEON) and Generalitat de Catalunya 2009 SGR 770. We thank Giovanni Battista Pace for help with sample preparation and FTIR measurements.
KeyWords: State V-51 Nmr; Quaternary Chalcogenide Nanocrystals; V2o5/tio2 Catalysts; In-situ; Tio2; Oxidation; Nanowires; Spillover; Stability; Xylene
DOI: 10.1021/jp406518w

ImpactFactor: 4.835
Citations: 34
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