中孔洞二氧化鈦薄膜應用於光催化分解水產氫及靜電紡絲法製備奈米碳纖維應用於鋰離子二次電池之負極材料

本實驗第一部分使用揮發誘導自組裝法(EISA)製備中孔洞二氧化鈦薄膜，使用掃描電子顯微鏡(SEM)，X-射線繞射(XRD)，拉曼光譜(Raman spectra)和紫外光-可見光譜(UV-vis spectra)做特性分析。以不同煅燒溫度375 °С、400 °С、450 °С及500 °С及不同膜厚可得到混合不同比例的銳鈦礦(Anatase)及金紅石(Rutile)晶相的二氧化鈦。然後，將二氧化鈦做為薄膜電極應用於光電化學法做光催化實驗，經過光電流和產氫的分析後，我們得出結論，鍛燒溫度500 °С，薄膜厚度60 nm的二氧化鈦薄膜有較高的光電流密度1.149 mA/cm2。然而，經照光六小時的產氫量可達45.15 μmol，其產氫量是375 °С的二氧化鈦薄膜的2.8倍，濺鍍二氧化鈦與商用二氧化鈦P25的3倍。混合銳鈦礦及金紅石相所造成的協同效應認為是有助於電荷分離，減少電子電洞對的再結合率。第二部分為利用靜電紡絲法製備聚丙烯腈(PAN)奈米纖維，並經由穩定化與碳化程序，可得到奈米碳纖維(CNF)。將CNF與奈米碳顆粒(CNP)及商用中間相碳微球(MCMB)分別做SEM、XRD、Raman、TEM分析，比較三者表面形態與內部結構，CNF與CNP為無序堆疊的非晶碳結構，MCMB為石墨化有序的孔洞結構。此三種材料分別做為鋰離子二次電池之活性材料，組裝成半電池做充放電測試，CNP可得到最高的初始放電電容量(Discharge capacity) 385.17 mAh/g，在第一圈循環CNF及CNP有較高的不可逆電容量，主要歸因於固態電解質介面(Solid electrolyte interface, SEI)形成及無定形碳之結構，而MCMB則可得到最高的初始庫倫效率94.76 %；經十圈充放電後，三者的庫倫效率皆達到95 %以上，而CNF保留最高的充電電容量285.57 mAh/g ，MCMB僅249.57 mAh/g，與商用MCMB相比，具有較高的電容量是CNF的優勢。

關鍵字

氫氣；光催化；中孔洞二氧化鈦；分解水

並列摘要

Mesoporous TiO2 nano films were synthesized with a variety of calcination temperature and film thickness for water splitting application. The characterization of the materials were conducted with scanning electron microscope (SEM), X-ray diffraction (XRD), Raman analysis and UV–Vis spectra in order to know the ratio of the anatase and rutile phases of the TiO2. The experiments of water splitting were carried out with mesoporous TiO2 nano films. The results indicated that the nano film with 60 nm in thickness and synthesized at 500 °С had a higher photocurrent density of 1.149 mA/cm2 . The yield of hydrogen (45.15 μmol) 3 times than that of Sputter TiO2 and Degussa P25 thin film. The second part of research is the formation of the carbon nano fibers (CNF) by electrospinning, stabilization and carbonnization using polyacrylonitrile (PAN) as the precursor of carbon nanofibers. The diameter of CNF was about 320 nm while the length was about several meters. CNF, carbon nano particle (CNP) and mesocarbon microbead (MCMB) were analyzed by SEM, TEM, Raman and XRD. It was found that the CNF and CNP were turbostratic carbon, while the MCMB was the form of graphite. Three materials were used as anode materials for Li-ion batteries. The experimental results of the electrochemical studies showed that the CNP obtained the highest initial discharge capacity 385.17 mAh/g while the CNF and CNP had higher irreversible capacity. It was mainly because of the formation of SEI on the amorphous carbon. The MCMB obtained the highest initial coulombic efficiency 94.76 %. After ten cycles, the three materials had coulombic efficiency of more than 95 %, and the CNF had highest charge capacity 285.57 mAh/g, while MCMB was only 249.57 mAh/g. CNF was a higher capacity compared with commercial MCMB.

並列關鍵字

hydrogen ； photocatalyst ； mesoporous TiO2 ； water splitting

參考文獻

[1] Liao Y-T, Huang C-W, Liao C-H, Wu JCS, Wu KCW. Synthesis of mesoporous titania thin films (MTTFs) with two different structures as photocatalysts for generating hydrogen from water splitting. Applied Energy. 2012;100:75-80.

[3] Kho YK, Iwase A, Teoh WY, Madler L, Kudo A, Amal R. Photocatalytic H2 Evolution over TiO2 Nanoparticles. The Synergistic Effect of Anatase and Rutile. J Phys Chem C. 2010;114(6):2821-9.

[4] Levin EM. Phase diagrams for ceramists. The American Ceramic Society, Inc. 1975;76:4150-999.

[6] Jirgensons B, Straumanis ME. A short textbook of colloid chemistry Journal of Chemical Education. 1962;39(12):656.

[7] Dawson WJ. Hydrothermal synthesis of advanced ceramic powders. American Ceramic Society Bulletin. 1988;67(10):1673-8.

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中孔洞二氧化鈦薄膜應用於光催化分解水產氫及靜電紡絲法製備奈米碳纖維應用於鋰離子二次電池之負極材料

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