期刊
ACS APPLIED MATERIALS & INTERFACES
卷 6, 期 19, 页码 16808-16816出版社
AMER CHEMICAL SOC
DOI: 10.1021/am504158r
关键词
tungsten trioxide; gas-sensing; solvothermal synthesis
资金
- CSIC/CNR project [2010IT0001]
- SOLAR project [DM19447]
- ICREA Funding Source: Custom
We report for the first time the synthesis of monoclinic WO3 quantum dots. A solvothermal processing at 250 degrees C in oleic acid of W chloroalkoxide solutions was employed. It was shown that the bulk monoclinic crystallographic phase is the stable one even for the nanosized regime (mean size 4 nm). The nanocrystals were characterized by X-ray diffraction, High resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV-vis, Fourier transform infrared and Raman spectroscopy. It was concluded that they were constituted by a core of monoclinic WO3, surface covered by unstable W(V) species, slowly oxidized upon standing in room conditions. The WO3 nanocrystals could be easily processed to prepare gas-sensing devices, without any phase transition up to at least 500 degrees C. The devices displayed remarkable response to both oxidizing (nitrogen dioxide) and reducing (ethanol) gases in concentrations ranging from 1 to 5 ppm and from 100 to 500 ppm, at low operating temperatures of 100 and 200 degrees C, respectively. The analysis of the electrical data showed that the nanocrystals were characterized by reduced surfaces, which enhanced both nitrogen dioxide adsorption and oxygen ionosorption, the latter resulting in enhanced ethanol decomposition kinetics.
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