利用X光光譜對二氧化鈦奈米管陣列電子結構之研究

利用電化學陽極氧化法(Anodization)製備二氧化鈦納米管陣列(TiNT)，所調配之電解液主要成分為乙二醇(Ethylene glycol)，並且加入少量的氟化銨（NH4F）和過氧化氫溶液（H2O2），之後將清洗過後的鈦板放入並進行化學蝕刻，而得到所需之二氧化鈦奈米管。二氧化鈦納米管陣列具有良好的電子傳輸性能和卓越的光捕捉效應，高品質的納米管陣列在光伏電池和光電子元件的應用範圍很廣泛。在本研究對導電帶(Conduction band)和價電帶(Valence band)之電子(Electron)與電洞(Hole)的特性進行分析，通過掃描式光電子顯微鏡(Scanning photoelectron microscope, SPEM)、X光光電子能譜儀(X-ray Photoelectron Spectroscopy, XPS)和X光吸收光譜(X-ray Absorption Spectroscopy, XAS）。從電子結構特徵所表現出之特性，指出在二氧化鈦奈米管之底部與頂端有所不同，不論在價態、晶體場分裂、八面體對稱性上都有明顯的不同。此外，也從延伸X光吸收光譜精細結構(EXAFS)中發現，在二氧化鈦奈米管的配位數、鍵長、原子結構上都可看見差異性，於是經由一系列之檢測串連其相關特性進行進一步的探討。

關鍵字

太陽能電池；陽極氧化法；二氧化鈦； X光吸收光譜

並列摘要

The TiO2 nanotubes (TiNT) arrays were fabricated by electrochemical anodic oxidation method at room temperature using Ti foil in ethanol containing ammonium fluoride (NH4F) and hydrogen peroxide solution (H2O2). The TiO2-nanotube arrays exhibit favorable electron transport properties and superior light-harvesting efficiency. The high quality arrayed nanotubes can be used to the wide range of applications in photovoltaic cells and optoelectronic devices. In this report, the conduction/valence band and electron/hole transportation of the TiNTs are investigated by scanning photoelectron microscopy (SPEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy(XAS) . The electronic structural characterization reveal that the catalytic property strongly correlates with the Ti 3d-O 2p hybridization. It reveals that the electronic structure around Ti site is varied in the bottom and the top of the nanotube. In addition, the local atomic structure of these TiNTs are also investigated by extended X-ray absorption for fine structure (EXAFS).

並列關鍵字

DSSC ； Anodization ； Titanium dioxide ； XAS ； XPS

參考文獻

[1] M. Gratzel, ”Photoelectrochemical cells,” Nature, Vol.414, 2001, p.338

[2] M. Gratzel, P. Liska, J. Augustynski, and N. Vlachopoulos, “Very Efficient Visible Light Energy Harvesting and Conversionby Spectral Sensitization of High Surface Area PolycrystallineTitanium Dioxide Films,” Journal of the American Chemical Society, Vol. 110, 1988, p.1216.

[3] B. O’Regan, M. Gratzel, “A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films,” Nature, Vol. 353, 1991, p. 737.

[4] Y. Xia, P. Yang, Y. Sun, Y. Wu, B. Mayers, B. Gates, Y. Yin, F. Kim and H. Yan, “One-Dimensional Nanostructures: Synthesis, Characterization, and Applications,” Advanced Materials, Vol. 15, 2003, p. 353.

[5] I. D. Kim, A. Rothschild, B. H. Lee, D. Y. Kim, S. M. Jo and H. L. Tuller, “Ultrasensitive Chemiresistors Based on Electrospun TiO2 Nanofibers,” Nano Letters, Vol. 6, 2006, p. 2009.

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利用X光光譜對二氧化鈦奈米管陣列電子結構之研究

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