In Situ Oxidation of Alkanethiol Groups and Proton Transfer in Nanopores of Sodium Borosilicate Glasses

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• 作者：Yusuke Daiko ; Hirokazu Katayama ; Takanobu Araki ; Atsushi Mineshige ; Masafumi Kobune ; Shin-ichi Yusa ; Tetsuo Yazawa ; Keisuke Nagasaka ; Shigeaki Murata ; Shinichi Matsumoto ; Akihiko Koiwai ; Ichiro Konomi
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：February 5, 2009
• 年：2009
• 卷：113
• 期：5
• 页码：1891-1895
• 全文大小：193K
• 年卷期：v.113,no.5(February 5, 2009)
• ISSN：1932-7455

文摘

Porous glasses with 4 nm diameter pores were prepared utilizing a spinodal-type phase separation of Na₂O−B₂O₃−SiO₂ glass, and the surface was modified by using mercaptoalkyltrimethoxysilane with different alkyl chain length ((CH₃O)₃Si(CH₂)_n-SH, n = 1, 3, 6, 10). The thiol groups (−SH) were oxidized with H₂O₂ to obtain −SO₃H groups. The amount of the introduced silane coupling agents and the reactivity with H₂O₂ inside the nanopores drastically changed by changing the alkyl chain length (n). The molecular structures, charge distributions, bond overlap populations (BOP) between Si and alkyl chains, as well as net charges of thiol groups were calculated based on a density functional theory and a first-principle theory (DVXα). The charge distribution calculations suggest that oxygen atoms on pores affect significantly for both the net charge of S and BOP, and the BOP values were directly related with the in situ oxidation reactivity of silane coupling agents. The porous glasses modified with the silane coupling agent with n = 1 showed high proton conductivity of 1 × 10⁻² S/cm at 80 °C and 90% relative humidity.