製備多層奈米碳管複合薄膜修飾電極偵測葉酸,過氧化氫和4-硝基酚

Fabrication of Multiwalled Carbon Nanotube Composite Film Modified Electrode for Electrochemical Determination of Folic Acid, H2O2 and 4-Nitrophenol

楊延齡(Yan-Ling Yang)

指導教授 ： 陳生明

國立臺北科技大學/工程學院/化學工程研究所/碩士(2010年)

摘要

本研究第一部分主要是藉由玻璃碳電極上的多層奈米碳管結合聚乙烯磺酸鈉修飾薄膜探討對葉酸 (FA) 還原特性。我們還分別利用AFM和EIS了解電極表面的特性和電子傳導現象。MWCNT/PVS修飾薄膜顯示出FA在pH 7緩衝溶液的良好電催化行為。當葉酸的還原波峰電位在 -0.7 V，波峰電流隨著FA濃度呈線性增加。計時安培法可得到偵測範圍為8.2 x 10-5 M 到 1.7 x 10-3 M。MWCNT/PVS薄膜修飾電極只對FA有還原電流產生，因此在對FA的測定中，此一修飾電極可提供具選擇性的偵測。
第二部分研究多層奈米碳管 (MWCNT)、聚乙烯磺酸鈉 (PVS)，細胞色素c (Cyt c) 包覆玻璃碳電極的電化學特性和作為過氧化氫 (H2O2) 感應器的應用。利用PVS帶有負電荷和具有FeIII/II正價離子的細胞色素c藉由靜電相吸，使MWCNT/PVS/Cyt c 修飾薄膜具有良好電化學特性。由不同掃描速率研究，顯示波峰電流和掃描速率關係呈線性增加。pH值變化顯示在電極表面發生兩個電子和一個質子的轉移。再藉由電化學阻抗分析儀和原子力顯微鏡觀察表面特性。最後由計時安培法得到MWCNT/PVS/Cyt c修飾薄膜玻璃碳電極偵測範圍為1 x 10-5 M到 7.4 x 10-4 M 的過氧化氫。

第三部份研究多層奈米碳管 (MWCNT) /聚二苯胺 (PDPA) 薄膜修飾電極對4-硝基酚 (4-Nitrophenol) 電催化還原反應的特性。DPA在5 M H2SO4溶液中電聚合在MWCNT 薄膜修飾電極上，利用電子掃描顯微鏡觀察表面型態和EIS研究修飾電極表面電子轉移現象。循環伏安法得到還原電位在 -0.7 V ，最後計時安培法顯示線性偵測範圍在1.3 x 10-4 M 到 1.28 x 10-3 M。

關鍵字

多層奈米碳管 ； 聚乙烯磺酸鈉 ； 細胞色素 c ； 4-硝基酚 ； 聚二苯胺

並列摘要

Part I：Folic acid (FA) is an important compound which takes part in various bodily functions ranging from nucleotide biosynthesis to the remethylation of homocysteine. We investigated the electrochemical reduction behavior of folic acid at a multi-walled carbon nanotube (MWCNT)/poly vinly sulfate (PVS) composite film modified glassy carbon electrode (GCE). The surface morphology of MWCNT/PVS was studied using atomic force microscope (AFM). The interfacial electron transfer phenomena at the modified electrode was studied using electrochemical impedance spectroscopy (EIS). The MWCNT/PVS composite film showed good electrocatalytic behavior towards the reduction of FA in pH 7. FA showed a well defined reduction peak at – 0.7 V (vs. Ag/AgCl electrode). The peak current increased linearly with FA concentration. The amperometric determination of FA at the composite film modified electrode showed linear range from 8.2 x 10-5 M to 1.7 x 10-3 M. The developed film shows good selectivity towards FA in presence of common interferences such as glucose, ascorbic acid, uric acid and dopamine. This result shows the potential application of the proposed film in real sample analysis.
Part II：We have researched the fabrication of a stable composite film of multi-walled carbon nanotubes (MWCNT), poly vinly sulfonic acid (PVS) and cytochrome c (Cyt c) on glassy carbon electrode (GCE), electrochemical characterization and its potential application as H2O2 sensor. The presence of PVS in the film enhanced the current and electrocatalytic activity of the film. The cyclic voltammetric responses (CV) in pH 7 exhibit prominent redox couple for the FeIII/II redox process corresponding to the Cyt c with the peak-to-peak separation (ΔE) of 64 mV. The different scan rate studies shows a linear increase in peak currents with scan rate which proves that the redox process is a surface confined process. The CV response of the composite film modified GCE in various pH that shows the electrochemical process taking place at the electrode surface is a two electron one proton transfer process. The composite film was characterized by Electrochemical Impedance Spectroscopy (EIS) and Atomic Force Microscopy (AFM). The composite film showed good electrocatalytic activity towards the reduction of H2O2 in pH 7. Amperometric i-t responses of MWCNT/PVS/Cyt c composite modified rotating disc glassy carbon electrode towards the H2O2 reduction were recorded at the applied potential of -0.2 V. The rotation speed was 1200 rpm. The film showed good stability with a linear range of 10 x 10-6 M to 7.4 x 10-4 M H2O2.
Part III：4-Nitrophenol (4-NP) is a toxic substance released to the atmosphere from pharmaceutical, pesticide and dye industries. Its determination in water samples is important. We investigated the electrochemical reduction behavior of 4-NP at a multi-walled carbon nanotube (MWCNT)/poly diphenylamine (PDPA) composite film modified glassy carbon electrode (GCE). PDPA was polymerized on the MWCNT modified GCE surface by cyclic voltammetry in 5 M H2SO4. The surface morphology of MWCNT/PDPA was studied using Scanning Electron Microscope (SEM). The interfacial electron transfer phenomena at the modified electrode was studied using electrochemical impedance spectroscopy (EIS). The MWCNT/PDPA composite film showed good electrocatalytic behavior towards the reduction of 4-NP in pH 7. 4-NP showed a well defined reduction peak at – 0.7 V (vs. Ag/AgCl electrode). The MWCNT in MWCNT/PDPA film enhanced the reduction peak current by 42 times and the oxidation peak current by 25 times than that of GCE/PDPA electrode. The peak current increased linearly with 4-NP concentration. The amperometric determination of 4-NP at the composite film modified electrode showed linear range from 1.3 x 10-4 M to 1.28 x 10-3 M. This result shows that the proposed composite electrode may be developed for potential application in real sample analysis.

並列關鍵字

MWCNT ； PVS ； Cyt c ； diphenylamine ； 4-Nitrophenol ； poly diphenylamine

參考文獻

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