隨著石化能源的耗竭與環保意識的高漲，不論是企業或是學術界，皆積極投入再生能源的研發，而氫能源更是由於其製作過程簡易、材料選擇廣、成本相對低與對環境友善，十分有潛力成為次世代能源之一。在眾多材料中，五氧化二鉭因其化學活性優於二氧化鉭且穩定性高，不易受環境影響，被廣為研究作為光催化材料。但五氧化二鉭最大缺點在於其能帶過於寬廣(>3.8 eV)，故吸收波段侷限在紫外光，導致產生氫氣之效率有限，為了增加五氧化二鉭在可見光之吸收波段，此研究結合氧化銅奈米顆粒能帶小且化學活性佳之優點 (1.73 eV)，期望此異質結構能夠在更廣泛之光波段產生電子電洞對，並且因能帶傾斜增加電子電洞對分離率，進而改善光催化裂解水產氫之效能。
本研究首先使用陽極電鍍法，製作出非結晶性之五氧化二鉭奈米管，在不同溫度之高溫熱處理後(800 0C持溫一小時)，增加奈米管之結晶性。結果顯示，結晶性與溫度成正相關，在800 0C下持溫一小時，可得到品質最佳之奈米管。接下來，使用蒸鍍機將銅奈米顆粒附著在奈米管上，進而使用低溫熱處理(200-400 0C)，將銅顆粒逐漸氧化成氧化銅奈米顆粒，在成長過程中發現，當溫度高於400 0C時，銅顆粒開始聚集成較大尺寸顆粒，大顆粒之氧化銅會降低其產氫效果，故300 0C持溫1分鐘下得到之氧化銅奈米顆粒，會得到產氫最佳效果。此異質結構因為奈米顆粒良好附著在奈米管上，且能階受到氧化銅之影響形成p-n 接面，造成界面能帶傾斜進而增加電子電洞對之分離率與降低其再結合率。而在不同的退火條件下，氧化銅包覆五氧化二鉭之異質結構其光催化裂解水產氫在紫外光下之效率比純五氧化二鉭奈米管分別高出70%，證明氧化銅奈米顆粒附著在五氧化二鉭奈米管上確實能增加其光催化效果，並應用於裂解水產氫之研究。

In recent years, investigating renewable energy resources, especially hydrogen energy production, is increasingly important in both industries and academia due to the shortage of fuel resources and the threatening of global warming. For hydrogen production, photocatalysts play the key role to overcome the troublesome problems. Among utilization of photocatalysts, tantalum oxide is a promising material for the photogeneration of hydrogen from water compared to widely used TiO2. The advantage is due to its conduction band minimum (CBM) is more negative than TiO2, leading to more photogenerated charge carriers to undergo hydrogen evolution reaction (HER). However, the wide band gap of Ta2O5 (>3.8eV) allows only utilizing UV-light, limiting its H2 production efficiency.
The present work aims at improving the rate of H2 evolution with extending the absorption region of solar spectrum by integrating Ta2O5 nanotubes with CuO nanoparticles, possessing a relatively small band gap (1.2-1.8 eV). The results clearly show that the H2 production efficiency of the heterostructure of CuO NPs/Ta2O5 NTs increased significantly, in particular with Cu NPs annealed at 300 °C. Due to their tunable band gap, well-grown interface, and fine particle size, the hydrogen production rates of CuO NPs/Ta2O5 NTs annealed at 300 °C are 70% more than pure
NTs. The results indicate that Ta2O5 NTs attached with CuO NPs are promising photocatalytic materials for hydrogen production.

Abstracts VI
摘要 VIII
Chapter 1. Introduction 1
1.1. Nanotechnology 1
1.2. Nanostructures 4
1.2.1. One-Dimensional Nanostructures 5
1.2.2. Semiconductor Nanotubes 5
1.3. Basic Properties of Tantalum Pentoxide (Ta2O5) 6
1.3.1. Crystal Structure 7
1.4. Basic Properties of Copper Oxide (CuxO) 11
1.4.1. Crystal Structure 11
1.4.2. Properties and Applications 15
1.5. Photocatalysis 17
1.5.1. Background 17
1.5.2. Hydrogen evolution for water splitting 18
Chapter 2. Experimental Procedures 23
2.1. Growth of Ta2O5 Nanotubes 23
2.2. Experimental Methods of CuO Nanoparticles/Ta2O5 Nanotubes 24
2.2.1. Physical Vapor Deposition 24
2.2.2. Electron Gun Deposition 25
2.3. Experimental Systems 26
2.3.1. Heating Furnace 26
2.3.2. Scanning Electron Microscope (SEM) 27
2.3.3. Transmission Electron Microscope (TEM) 28
2.3.4. X-ray Diffractometer (XRD) 28
2.3.5. X-ray Photoemission Spectrometer (XPS) 29
2.3.6. Ultraviolet and Visible Spectrometer (UV/VIS) 29
2.3.7. Energy Dispersive Spectrometer (EDS) 29
2.3.8. Gas Chromatography (GC) System 30
Chapter 3. Results and Discussion 32
3.1 Synthesis of Ta2O5 Nanotubes 32
3.2 Synthesis of Ta2O5 Nanotubes Attached with CuO Nanoparticles 35
3.2.1 Physical Vapor Deposition Method 35
3.2.2 E-beam Evaporation And Thermal Treatment 39
3.2.3 Effects of Attachment of CuO Nanoparticles on Ta2O5 Nanotubes on Hydrogen Generation 45
3.2.4 Influences of the CuO NPs/Ta2O5 NTs on Photocatalytic Performance
photoelectron-chemistry fields. 50
Chapter 4. Summary and Conclusions 52
Chapter 5. Future Prospects 54
5.1. Ta2O5 NTs Attached with Three Dimensional CuO NPs 54
5.2. The investigation of Interfacial Reaction Mechanism between CuO NPs and Ta2O5 NTs 58
References 60

[1] R.P. Feynman, There’s plenty of room at the bottom, Miniaturization, (1959) 282-296.
[2] M.-C. Daniel, D. Astruc, Gold nanoparticles: assembly, supramolecular chemistry, quantum-size-related properties, and applications toward biology, catalysis, and nanotechnology, Chemical Reviews, 104 (2004) 293-346.
[3] J. Liu, P. Kopold, P.A. van Aken, J. Maier, Y. Yu, Energy storage materials from nature through nanotechnology: a sustainable route from reed plants to a silicon anode for lithium‐ion batteries, Angewandte Chemie International Edition, 54 (2015) 9632-9636.
[4] W. Lu, C.M. Lieber, Nanoelectronics from the bottom up, Nature Materials, 6 (2007) 841-850.
[5] C. Koch, Top-Down Synthesis of nanostructured materials: mechanical and thermal processing methods, Reviews on Advanced Materials Science, 5 (2003) 91-99.
[6] X. Lu, C. Wang, Y. Wei, One‐dimensional composite nanomaterials: synthesis by electrospinning and their applications, Small, 5 (2009) 2349-2370.
[7] Y.S. Zhao, H. Fu, F. Hu, A. Peng, W. Yang, J. Yao, Tunable emission from binary organic one‐dimensional nanomaterials: an alternative approach to white‐light emission, Advanced Materials, 20 (2008) 79-83.
[8] C.J. Murphy, T.K. Sau, A. Gole, C.J. Orendorff, Surfactant-directed synthesis and optical properties of one-dimensional plasmonic metallic nanostructures, MRS Bulletin, 30 (2005) 349-355.
[9] S. Iijima, T. Ichihashi, Single-shell carbon nanotubes of 1-nm diameter, Nature, 363 (1993) 603-605.
[10] C.M. Lieber, One-dimensional nanostructures: chemistry, physics & applications, Solid State Communications, 107 (1998) 607-616.
[11] Y. Xia, P. Yang, Y. Sun, Y. Wu, B. Mayers, B. Gates, Y. Yin, F. Kim, H. Yan, One‐dimensional nanostructures: synthesis, characterization, and applications, Advanced Materials, 15 (2003) 353-389.
[12] K. Takeuchi, T. Hayashi, Y. Kim, K. Fujisawa, The State-of-the-art science and applications of carbon nanotubes, Nanosystems: Physics, Chemistry, Mathmatics, 5 (2014) 15-24.
[13] P. Roy, S. Berger, P. Schmuki, TiO2 nanotubes: synthesis and applications, Angewandte Chemie International Edition, 50 (2011) 2904-2939.
[14] C. Askeljung, B.-O. Marinder, M. Sundberg, Effect of heat treatment on the structure of L-Ta2O5: a study by XRPD and HRTEM methods, Journal of Solid State Chemistry, 176 (2003) 250-258.
[15] N. Stephenson, R. Roth, Structural systematics in the binary system Ta2O5–WO3. V. The structure of the low-temperature form of tantalum oxide L-Ta2O5, Acta Crystallographica Section B: Structural Crystallography and Crystal Chemistry, 27 (1971) 1037-1044.
[16] A.F. Wells, Structural Inorganic Chemistry, Oxford University Press (2012).
[17] G. Wolten, A. Chase, Single-crystal data for ß Ta2O5 and A KP03, Z. Kristallogr, 129 (1969) 365-368 .
[18] I. Zibrov, V. Filonenko, M. Sundberg, P.-E. Werner, Structures and phase transitions of B- Ta2O5 and Z- Ta2O5: two high-pressure forms of Ta2O5, Acta Crystallographica Section B: Structural Science, 56 (2000) 659-665.
[19] P.W. Ho, F.O. Hatem, H.A.F. Almurib, T.N. Kumar, Comparison between Pt/TiO2/Pt and Pt/TaO X/TaO Y/Pt based bipolar resistive switching devices, Journal of Semiconductors, 37 (2016) 064001.
[20] B.O. Loopstra, Neutron diffraction investigation of U3O8, Acta Crystallographica, 17 (1964) 651-654.
[21] C. Chaneliere, J. Autran, R. Devine, B. Balland, Tantalum pentoxide (Ta 2 O 5) thin films for advanced dielectric applications, Materials Science And Engineering: R: Reports, 22 (1998) 269-322.
[22] K. Sayama, H. Arakawa, Effect of Na2CO3 addition on photocatalytic decomposition of liquid water over various semiconductor catalysis, Journal of Photochemistry and Photobiology A: Chemistry, 77 (1994) 243-247.
[23] P. Zhang, J. Zhang, J. Gong, Tantalum-based semiconductors for solar water splitting, Chemical Society Reviews, 43 (2014) 4395-4422.
[24] H. Kominami, M. Miyakawa, S.-y. Murakami, T. Yasuda, M. Kohno, S.-i. Onoue, Y. Kera, B. Ohtani, Solvothermal synthesis of tantalum (V) oxide nanoparticles and their photocatalytic activities in aqueous suspension systems, Physical Chemistry Chemical Physics, 3 (2001) 2697-2703.
[25] T. Sreethawong, S. Ngamsinlapasathian, Y. Suzuki, S. Yoshikawa, Nanocrystalline mesoporous Ta2O5-based photocatalysts prepared by surfactant-assisted templating sol–gel process for photocatalytic H2 evolution, Journal of Molecular Catalysis A: Chemical, 235 (2005) 1-11.
[26] D. Jing, L. Guo, Hydrogen production over Fe-doped tantalum oxide from an aqueous methanol solution under the light irradiation, Journal of Physics and Chemistry of Solids, 68 (2007) 2363-2369.
[27] L. Xu, J. Guan, L. Gao, Z. Sun, Preparation of heterostructured mesoporous In 2 O 3/Ta 2 O 5 nanocomposites with enhanced photocatalytic activity for hydrogen evolution, Catalysis Communications, 12 (2011) 548-552.
[28] L. Xu, J. Guan, W. Shi, Enhanced interfacial charge transfer and visible photocatalytic activity for hydrogen evolution from a Ta2O5‐based mesoporous composite by the incorporation of quantum‐sized CdS, Chemcatchem, 4 (2012) 1353-1359.
[29] R.V. Gonçalves, P. Migowski, H. Wender, D. Eberhardt, D.E. Weibel, F.C. Sonaglio, M.J. Zapata, J. Dupont, A.F. Feil, S.R. Teixeira, Ta2O5 nanotubes obtained by anodization: effect of thermal treatment on the photocatalytic activity for hydrogen production, The Journal of Physical Chemistry C, 116 (2012) 14022-14030.
[30] J. Huang, R. Ma, Y. Ebina, K. Fukuda, K. Takada, T. Sasaki, Layer-by-Layer assembly of TaO3 nanosheet/polycation composite nanostructures: Multilayer film, hollow sphere, and its photocatalytic activity for hydrogen evolution, Chemistry of Materials, 22 (2010) 2582-2587.
[31] S. Lin, L. Shi, H. Yoshida, M. Li, X. Zou, Synthesis of hollow spherical tantalum oxide nanoparticles and their photocatalytic activity for hydrogen production, Journal of Solid State Chemistry, 199 (2013) 15-20.
[32] S. Åsbrink, L.-J. Norrby, A refinement of the crystal structure of copper (II) oxide with a discussion of some exceptional esd's, Acta Crystallographica Section B: Structural Crystallography and Crystal Chemistry, 26 (1970) 8-15.
[33] P. Poizot, C.-J. Hung, M.P. Nikiforov, E.W. Bohannan, J.A. Switzer, An electrochemical method for CuO thin film deposition from aqueous solution, Electrochemical and Solid-State Letters, 6 (2003) C21-C25.
[34] C. Vidyasagar, Y.A. Naik, T. Venkatesha, R. Viswanatha, Solid-state synthesis and effect of temperature on optical properties of CuO nanoparticles, Nano-Micro Letters, 4 (2012) 73-77.
[35] V. Palkar, P. Ayyub, S. Chattopadhyay, M. Multani, Size-induced structural transitions in the Cu-O and Ce-O systems, Physical review B, 53 (1996) 2167.
[36] K. Nakaoka, J. Ueyama, K. Ogura, Photoelectrochemical behavior of electrodeposited CuO and Cu2O thin films on conducting substrates, Journal of the Electrochemical Society, 151 (2004) C661-C665.
[37] Y. Hori, K. Kikuchi, S. Suzuki, Production of CO and CH4 in electrochemical reduction of CO2 at metal electrodes in aqueous hydrogencarbonate solution, Chemistry Letters, 14 (1985) 1695-1698.
[38] S. Somasundaram, C.R.N. Chenthamarakshan, N.R. de Tacconi, K. Rajeshwar, Photocatalytic production of hydrogen from electrodeposited p-Cu2O film and sacrificial electron donors, International Journal of Hydrogen Energy, 32 (2007) 4661-4669.
[39] Q. Zhang, K. Zhang, D. Xu, G. Yang, H. Huang, F. Nie, C. Liu, S. Yang, CuO nanostructures: synthesis, characterization, growth mechanisms, fundamental properties, and applications, Progress in Materials Science, 60 (2014) 208-337.
[40] A. Salant, M. Shalom, I. Hod, A. Faust, A. Zaban, U. Banin, Quantum dot sensitized solar cells with improved efficiency prepared using electrophoretic deposition, ACS Nano, 4 (2010) 5962-5968.
[41] M. Alonso, I. Marcus, M. Garriga, A. Goni, J. Jedrzejewski, I. Balberg, Evidence of quantum confinement effects on interband optical transitions in Si nanocrystals, Physical Review B, 82 (2010) 045302.
[42] W.E. Buhro, V.L. Colvin, Semiconductor nanocrystals: shape matters, Nature Materials, 2 (2003) 138-139.
[43] S. Rehman, A. Mumtaz, S. K. Hasanain, Size effects on the magnetic and optical properties of CuO nanoparticles, J Nanopart Res, 13 (2011) 2497–2507.
[44] M.G. Walter, E.L. Warren, J.R. McKone, S.W. Boettcher, Q. Mi, E.A. Santori, N.S. Lewis, Solar water splitting cells, Chemical Reviews, 110 (2010) 6446-6473.
[45] R. Agrawal, M. Offutt, M.P. Ramage, Hydrogen economy‐an opportunity for chemical engineers, AIChE Journal, 51 (2005) 1582-1589.
[46] A. Kudo, Y. Miseki, Heterogeneous photocatalyst materials for water splitting, Chemical Society Reviews, 38 (2009) 253-278.
[47] X. Chen, S. Shen, L. Guo, S.S. Mao, Semiconductor-based photocatalytic hydrogen generation, Chemical Reviews, 110 (2010) 6503-6570.
[48] F.E. Osterloh, B.A. Parkinson, Recent developments in solar water-splitting photocatalysis, MRS Bulletin, 36 (2011) 17-22.
[49] N. Bao, L. Shen, T. Takata, K. Domen, Self-templated synthesis of nanoporous CdS nanostructures for highly efficient photocatalytic hydrogen production under visible light, Chemistry of Materials, 20 (2007) 110-117.
[50] R.V. Gonçalves, R. Wojcieszak, P.M. Uberman, S.R. Teixeira, L.M. Rossi, Insights into the active surface species formed on Ta2O5 nanotubes in the catalytic oxidation of CO, Physical Chemistry Chemical Physics, 16 (2014) 5755-5762.
[51] D. Tahir, S. Tougaard, Electronic and optical properties of Cu, CuO and Cu2O studied by electron spectroscopy, Journal of Physics: Condensed Matter, 24 (2012) 175002.
[52] S. Rehman, A. Mumtaz, S. Hasanain, Size effects on the magnetic and optical properties of CuO nanoparticles, Journal of Nanoparticle Research, 13 (2011) 2497-2507.
[53] T.-H. Yang, Y.-W. Harn, M.-Y. Pan, L.-D. Huang, M.-C. Chen, B.-Y. Li, P.-H. Liu, P.-Y. Chen, C.-C. Lin, P.-K. Wei, Ultrahigh density plasmonic hot spots with ultrahigh electromagnetic field for improved photocatalytic activities, Applied Catalysis B: Environmental, 181 (2016) 612-624.
[54] M.-H. Chang, H.-S. Liu, C.Y. Tai, Preparation of copper oxide nanoparticles and its application in nanofluid, Powder Technology, 207 (2011) 378-386.
[55] M. Yin, C.-K. Wu, Y. Lou, C. Burda, J.T. Koberstein, Y. Zhu, S. O'Brien, Copper oxide nanocrystals, Journal of the American Chemical Society, 127 (2005) 9506-9511.