| 中文摘要 |
本研究以高純度石墨及使用自行合成之高深寬比（high aspect ratio）多壁奈米碳管（multi-walled carbon nanotubes, MWCNT）為基質（matrix），製備奈米複合碳基電極（Nanocomposite carbon electrodes）。為了客觀的評估其電化學活性，本研究同時以所製備的奈米碳基複合電極，對標的物水溶液，鐵氰化鉀/亞鐵氰化鉀（[Fe（CN）₆]³⁻/ [Fe（CN）₆]⁴⁻,以Fe（III）/ Fe（II）代表），以循環伏安法（cyclic voltammetry, CV）進行氧化-還原特性測試，並將結果與經典的鉑電極（platinum electrode）和玻碳電極（glassy carbon electrode）比較。結果顯示：根據Randles-Sevcik關係式作圖，鉑電極上Fe（III）/ Fe（II）氧化還原對，具有良好的可逆性（reversibility）。帶入公式計算，得到氧化/還原程序（anodic/cathodic process）之擴散係數，Da / Dc= 5.6 / 6.4´10-6 cm2 / s。此數值與文獻記載相符。針對Fe（III）/ Fe（II）可逆反應的測試顯示：複合碳基電極的活性優於玻碳電極，但較白金略低。且均滿足Randles-Sevcik關係式,證明其電極反應為質傳控制（diffusion-controlled）；僅白金電極符合各項可逆性測試，其餘電極反應均屬準可逆反應（quasi-reversible）。
沒食子酸（gallic acid, GA）是一種應用廣泛的天然多酚化合物。具有優良的抗氧化性。為改進玻碳電極對於沒食子酸的電化學活性不足的缺點，本研究嘗試改以自製的複合碳基電極進行反應。結果顯示複合碳基電極之反應特性較為接近理想值，證明此電極活性較佳，且電子傳輸特性較好。 |
| 英文摘要 |
Carbon paste composite electrodes were fabricated using high-impurity graphite and large-aspect-ratio multi-walled carbon nanotubes (CNTs). The as-prepared carbon paste electrodes were evaluated against platinum and glassy carbon electrodes by using cyclic voltammetry on the [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻(ferri/ferro) redox couple and gallic acid (GA) oxidation in 0.1 M phosphate–phthalate buffer solutions at various pH levels.
The three electrode types exhibited good electrochemical activity in the redox couple reaction. The platinum electrode had diffusion coefficients of Da = 5.6×10−6 cm2/s and Dc = 6.4×10−6 cm2/s; these coincided with well-accepted values and indicate the well-functioning of the system.
In the anodic oxidation of GA, the as-fabricated CNT electrodes had more active electrochemical activity than the glassy carbon electrodes did. Theoretically, per the Nernst equation for a 2e−, 2H+ proton-coupled electron transfer, the variation in potential is 59 mV per unit of pH. Empirically, a linear regression on the data indicated a corresponding slope of−64.9 mV/pH; this is close to the theoretical value and demonstrates the responsiveness of the CNT electrodes to GA oxidation. |
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