Selective Improvement of NO2 Gas Sensing Behavior in SnO2 Nanowires by Ion-Beam Irradiation

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• 作者：Yong Jung Kwon ; Sung Yong Kang ; Ping Wu ; Yuan Peng ; Sang Sub Kim ; Hyoun Woo Kim
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：June 1, 2016
• 年：2016
• 卷：8
• 期：21
• 页码：13646-13658
• 全文大小：874K
• 年卷期：0
• ISSN：1944-8252

文摘

We irradiated SnO₂ nanowires with He ions (45 MeV) with different ion fluences. Structure and morphology of the SnO₂ nanowires did not undergo noticeable changes upon ion-beam irradiation. Chemical equilibrium in SnO₂/gas systems was calculated from thermodynamic principles, which were used to study the sensing selectivity of the tested gases, demonstrating the selective sensitivity of the SnO₂ surface to NO₂ gas. Being different from other gases, including H₂, ethanol, acetone, SO₂, and NH₃, the sensor response to NO₂ gas significantly increases as the ion fluence increases, showing a maximum under an ion fluence of 1 × 10¹⁶ ions/cm². Photoluminescence analysis shows that the relative intensity of the peak at 2.1 eV to the peak at 2.5 eV increases upon ion-beam irradiation, suggesting that structural defects and/or tin interstitials have been generated. X-ray photoelectron spectroscopy indicated that the ionic ratio of Sn^2+/Sn⁴⁺ increases by the ion-beam irradiation, supporting the formation of surface Sn interstitials. Using thermodynamic calculations, we explained the observed selective sensing behavior. A molecular level model was also established for the adsorption of NO₂ on ion-irradiated SnO₂ (110) surfaces. We propose that the adsorption of NO₂-related species is considerably enhanced by the generation of surface defects that are comprised of Sn interstitials.