Selective Plasmonic Gas Sensing: H2, NO2, and CO Spectral Discrimination by a Single Au-CeO2 Nanocomposite Film

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• 作者：Nicholas A. Joy ; Manjula I. Nandasiri ; Phillip H. Rogers ; Weilin Jiang ; Tamas Varga ; Satyanarayana V. N. T. Kuchibhatla ; Suntharampillai Thevuthasan ; Michael A. Carpenter
• 刊名：Analytical Chemistry
• 出版年：2012
• 出版时间：June 5, 2012
• 年：2012
• 卷：84
• 期：11
• 页码：5025-5034
• 全文大小：510K
• 年卷期：v.84,no.11(June 5, 2012)
• ISSN：1520-6882

文摘

A Au-CeO₂ nanocomposite film has been investigated as a potential sensing element for high-temperature plasmonic sensing of H₂, CO, and NO₂ in an oxygen containing environment. The CeO₂ thin film was deposited by molecular beam epitaxy (MBE), and Au was implanted into the as-grown film at an elevated temperature followed by high temperature annealing to form well-defined Au nanoclusters. The Au-CeO₂ nanocomposite film was characterized by X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). For the gas sensing experiments, separate exposures to varying concentrations of H₂, CO, and NO₂ were performed at a temperature of 500 掳C in oxygen backgrounds of 5.0, 10, and 21% O₂. Changes in the localized surface plasmon resonance (LSPR) absorption peak were monitored during gas exposures and are believed to be the result of oxidation鈥搑eduction processes that fill or create oxygen vacancies in the CeO₂. This process affects the LSPR peak position either by charge exchange with the Au nanoparticles (AuNPs) or by changes in the dielectric constant surrounding the particles. Spectral multivariate analysis was used to gauge the inherent selectivity of the film between the separate analytes. From principal component analysis (PCA), unique and identifiable responses were seen for each of the analytes. Linear discriminant analysis (LDA) was also used and showed separation between analytes as well as trends in gas concentration. Results indicate that the Au-CeO₂ thin film is selective to O₂, H₂, CO, and NO₂ in separate exposures. This, combined with the observed stability over long exposure periods, shows the Au-CeO₂ film has good potential as an optical sensing element for harsh environmental conditions.