Local geometric and electronic structures of gasochromic VOx films

Wei Luen Jang, Yang Ming Lu, Chi Liang Chen, Ying Rui Lu, Chung Li Dong*, Ping Hung Hsieh, Weng Sing Hwang, Jeng Lung Chen, Jin Ming Chen, Ting Shan Chan, Jyh Fu Lee, Wu-Ching Chou

*Corresponding author for this work

Research output: Contribution to journalArticle

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Abstract

VOx films were deposited by radio-frequency reactive magnetron sputtering from a vanadium target at room temperature. Local atomic and electronic structures of the films were then modified by thermal annealing. The oxidation state and structural and gasochromic properties of the films were elucidated by X-ray absorption spectroscopy. Analytical results indicate that the as-deposited VOx films were amorphous with mixed V4+ and V5+ valences. The amorphous VOx had a disordered and expanded lamellar structure resembling that of polymer-intercalated V 2O5 gels. VOx films were crystallized into orthorhombic V2O5 at 300 °C, and the lamellar structure was eliminated at 400 °C. Additionally, the gasochromic reaction reduced the vanadium valence via intervalence transitions between V5+ and V3+. Moreover, removing the lamellar structure reduced the gasochromic rate, and the gasochromic reaction transformed the V 2O5 crystalline phase irreversibly into an H 1.43V2O5 phase. Based on the results of this study, amorphous VOx with a lamellar structure is recommended for use in H2 gas sensors.

Original languageEnglish
Pages (from-to)4699-4708
Number of pages10
JournalPhysical Chemistry Chemical Physics
Volume16
Issue number10
DOIs
StatePublished - 14 Mar 2014

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    Jang, W. L., Lu, Y. M., Chen, C. L., Lu, Y. R., Dong, C. L., Hsieh, P. H., Hwang, W. S., Chen, J. L., Chen, J. M., Chan, T. S., Lee, J. F., & Chou, W-C. (2014). Local geometric and electronic structures of gasochromic VOx films. Physical Chemistry Chemical Physics, 16(10), 4699-4708. https://doi.org/10.1039/c3cp54773f