| 摘要: | 由於經濟以及環境需求，我們對於產能研究需求日益增加。然而，混和生物燃料電池正是符合我們目前所需的發展。本篇研究使用奈米碳管(CNT)-Laccase複合材料作為陰極，而陽極使用白金雙合金沉降於polyaniline-coated的奈米碳管(PANICNT)。CNT-Laccase藉由傅立葉轉換紅外光譜儀(FTIR)、表面電子顯微鏡(SEM)、熱重分析儀(TGA)來作為性質分析。CNT-Laccase藉由FTIR可看出具有官能基結構，例如:氫氧根、胺基以及氨基。並且由SEM顯示出將laccase固定於奈米碳管不但不會破壞結構，並且可以有效地聚集CNT-Laccase。將此結構做元素分析發現，氧原子以及氮原子的比例可進一步確認是laccase接於CNT上。因此，FTIR和SEM在此證明此實驗能成功將laccase鍵接於CNT上。TGA顯示CNT-Laccase經歷了兩個分解溫度，分別文310?C和670?C，此實驗結果可以說明CNT-Laccase是分為CNT以及Laccase兩個部份來分解。固定相的Laccase同時也改變了CNT的熱穩定性。將Laccase固定於CNT上也同時影響了Laccase的酵素活性，並且在高溫以及中性條件下使其穩定性也同時增強；我們知道在65?C時，Laccase就已失去其本身活性。然而CNT-Laccase在45?C時仍然可以維持其57.12%的酵素活性。CNT-laccase在pH=7時的活性大約7.04%，在pH=5時表現出的活性比Laccase單體更高。CNT-Laccase在沒有加入ABTS(2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)的情形之下無法作為氧還原的媒介。在本實驗中，ABTS作為電極以及Laccase活性部位的電子轉移媒介。然而氧還原活性的效能是取決於高分子黏著劑的種類與其組成。相較於polyvinyl alcohol(PVA)，Nafion能更有效地提供適合的化學環境進行氧還原。使用Nafion與緩衝溶液1:10的電流密度為1.31 mA/cm2，高於使用PVA的1.01 mA/cm2。增加高分子黏著劑的比例由1:2至1:1時，則會逐漸破壞氧還原活性。此外，在陽極的部分，我們以葡萄糖做氧化測試來測得其活性，所測試的合金分別為PtSn,、Pt3Sn、Pt,和 PtPb。我們藉由X光繞射儀(XRD)測得白金的FCC結構的變化進而確定合金的形成。而我們使用穿隧式電子顯微鏡(TEM)來確定上述合金的確能夠沉降並附著於PANICNT的表面。上述合金皆能在中性及鹼性條件下氧化葡萄糖。活性的表現則是由第二金屬的存在而改變。PtSn/PANICNT在本實驗中有最高的電流密度以及靈敏度，進而推斷其展現了最高的活性。其電流密度在鹼性以及中性條件下皆為8.27 mA/cm2。PtSn/PANICNT在0.0伏特以及0.1伏特的條件下分別測得39.64 μAcm-2mM-1和39.54 μAcm-2mM-1的靈敏度。另一方面，PtPb/PANICNT在-0.1V高靈敏度(40.33 μAcm-2mM-1)的條件下可使葡萄糖的氧化電位降低至。Economic and environmental requirements have motivated research in energy generation. Here, hybrid biofuel cell have been developed to meet the need. The cathode composed of laccase immobilized on CNT (CNT-Laccase), while the anode is Pt bimetallic alloy deposited on polyaniline-coated carbon nanotube (PANICNT). CNT-Laccase was characterized by Fourier Transform Infrared (FTIR) Spectrophotometry, Surface Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). CNT-Laccase FTIR spectra showed that the structure contain several functional groups, such as hydroxyl, amine and amide. SEM figures revealed that immobilization didn’t destroy tube structure of CNT, but it promoted aggregation. Elemental analysis of the structure displayed oxygen and nitrogen atoms distribution indicating the presence of Laccase. Therefore, FTIR and SEM reasserted successful immobilization. TGA reveal CNT-Laccase possesses two decomposition temperatures at 310?C and 670?C, that are related to decomposition of Laccase part and CNT part of CNT-Laccase, respectively. Laccase immobilization has changed CNT thermo stability. Immobilization also affected Laccase enzymatic activity where it boosts the stability at high temperature and neutral pH. At temperature 65?C, free Laccase completely loss its activity, while CNT-Laccase still retaining 57.12% of its activity at 45?C. The activity of CNT laccase at pH 7 was 7.04% of activity at pH 5 which was higher than that of free Laccase. CNT-Laccase was not able to perform oxygen electroreduction without addition ABTS (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) as mediator. In our case, ABTS was needed to shuttle electrons from electrode to Laccase active site. Performance of oxygen electroreduction activity was also determined by type and composition of binding polymer. Nafion was able to provide better environment for oxygen electroreduction activity compare to polyvinyl alcohol (PVA). Current density resulted in using Nafion in ratio 1:10 to buffer volume was 1.31 mA/cm2, which was higher than that of PVA (1.01 mA/cm2). Increasing binding polymer ratio into 1:2 and 1:1 undermined oxygen electroreduction activity.?On the anode side, the alloy such as PtSn, Pt3Sn, Pt, and PtPb were tested to analyze their activity toward glucose electrooxidation. The formation of alloy was confirmed by shifted Pt fcc patterns on X-ray Diffraction (XRD) analysis. The alloys were able to be deposited on PANICNT surface as confirmed by Transmission Electron Microscopy (TEM) images. All the metal alloys were able to oxidize glucose in neutral and basic solution. The activity is affected by the presence of secondary atom. PtSn/PANICNT showed the highest activity as reflected by the highest current density and highest sensitivity. The current density was about 8.27 mA/cm2 and 8.27 mA/cm2 at basic and neutral pH, respectively. The highest sensitivity for PtSn/PANICNT was achieved at potential 0.0 V and 0.1 V, which were about 39.64 μAcm-2mM-1 and 39.54 μAcm-2mM-1 respectively. On the other hand, PtPb/PANICNT shifted glucose electrooxidation to lower potential as the highest sensitivity (40.33 μAcm-2mM-1) was achieved at -0.1 V. |
