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    請使用永久網址來引用或連結此文件: http://ir.lib.ncu.edu.tw/handle/987654321/71377


    題名: Adsorption and Electrochemical Polymerization of Pyrrole on Au (100) Electrode as Examine by In Situ Scanning Tunneling Microscopy;Adsorption and Electrochemical Polymerization of Pyrrole on Au (100) Electrode as Examine by In Situ Scanning Tunneling Microscopy
    作者: 柯艾妲;Khairunnisa,Alda
    貢獻者: 化學學系
    關鍵詞: Polypyrrole;Pyrrole;Scanning Tunneling Microscopy;Au(100);Polymerization;Polypyrrole;Pyrrole;Scanning Tunneling Microscopy;Au(100);Polymerization
    日期: 2016-08-26
    上傳時間: 2016-10-13 12:47:40 (UTC+8)
    出版者: 國立中央大學
    摘要: 摘要
    研究聚吡咯的分子結構與形貌對於瞭解其作為一個導電高分子的電化學性質是很重要
    的。首先,本實驗第一部分以掃描式穿隧電子顯微鏡(STM)即時觀察於金(100)上吡咯的分子
    吸附及其聚合過程。由 STM的結果顯示,吡咯與硫酸氫根會在 0.55V(vs. RHE)於金(100)上呈現
    共吸附的結構( 4√2 x 4 √2 ),其覆蓋度為 0.125。當電位在大於 0.8V 時進行掃描則會使聚吡咯
    呈現彎曲結構。循環伏安法(CV)顯示在 0.1M硫酸中加入 30mM吡咯會在 0.42V得到一對可逆
    的吡咯吸脫附峰,而於 0.8V 則有一個氧化電流出現,此為吡咯開始聚合的特徵。此外,在金
    (111)上STM則觀察到雜亂的吡咯吸附,而CV則無法觀察到任何吡咯之吸附特徵。
    實驗第二部分中,以碘修飾的金(100)可以幫助聚吡咯更輕易地吸附於電極表面並經由
    高解像得到其結構。根據 STM 顯示,在硫酸下由電位掃描聚合的聚吡咯會同時具有 α-α 耦合
    以及少量 α-β 耦合的情況。當聚吡咯氧化後,硫酸氫根會以陰離子的形式圍繞在聚吡咯鏈旁和
    其正電荷作用使其結構彎曲,而此彎曲結構因其單鍵旋轉而同時具有同向和異向之型態。此外,
    CV 和 STM 中,在 pH4,0.1M 硫酸鉀(以硫酸調節 pH)中形成之聚吡咯,其寡聚物和聚吡咯之
    結構與 0.1M硫酸環境下聚合之結果相似,但高 pH值下聚吡咯之形成較緩慢。而從 FTIR結果
    顯示其兩種電解質皆有相同吸收帶於1586、1280、900和820 cm-1,此為C=C和C-N鍵之伸縮
    以及C-H鍵之彎曲訊號,並無C=O之官能基訊號。而由IR結果可知,此兩種電解質皆可聚合
    出理想的聚吡咯分子結構。
    ;Studies the molecular structures and conformation of polypyrrole (Ppy) are important to the understanding of their electrochemical properties as a conducting polymer. This thesis describes, for the first time, in situ scanning tunneling microscopy (STM) imaging the molecular adsorption and polymerization of pyrrole on Au (100) single crystal electrode. Obtained results reveal highly ordered Au(100) – (4 √2 x 4 √ 2 x pyrrole + bisulfate (HSO4- ) at 0.55 V vs. reversible hydrogen electrode (RHE) with 0.125 coverage. Continuous STM scanning at E > 0.8V discerns Ppy polymers assuming winding structures. Meanwhile, voltammetric results recorded in 0.1 M H2SO4 containing 30 mM pyrrole show a pair of reversible peak at 0.42 V, attributed to pyrrole adsorption. The oxidation current increases notably at 0.8 V, as pyrrole molecule is oxidized and polymerized. By contrast, STM reveals a disordered pyrrole adlayer on Au(111) electrode and the voltammetry result shows mostly featureless profile.
    Modification of Au (100) with an iodine adlayer can strengthen interaction between Ppy and Au(100), which helps in achieving high-resolution STM images. Aided by molecular resolution STM images, one recognizes that the as-prepared Ppy can have linkages of not only α-α, but also α-β coupling, although the latter is relatively unimportant. After Ppy is oxidized, HSO4- anions are drawn into the film by positively charged Ppy. This interaction generates Ppy with crooked molecular structure in syn or anti conformations. CV and STM results are also obtained with Ppy formed in pH 4 0.1 M K2SO4 (adjusted by adding H2SO4), revealing oligomer pyrrole and Ppy molecules structurally similar to those seen in 0.1 M H2SO4,
    although the rate of polymerization was slow in the higher pH medium. FTIR results obtained with the as-prepared Ppy have same absorption bands at 1586, 1280, 900, and 820 cm-1, which are ascribed to stretching of C=C and C-N bonds and bending of C-H bond
    without presence C=O functional group. Thus, these IR results suggest that both electrolytes can have the ideal molecular structure of Ppy.
    顯示於類別:[化學研究所] 博碩士論文

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