在本論文中，我們利用化學氣相沉積法(Chemical Vapor Deposition, CVD) 在二氧化矽/矽基板上製作具高效能氧化銦奈米線光電極並應用於光電化學系統進行水分解。實驗分為三個部分，第一個部分，我們研究不同氧流量的調變對氧化銦奈米結構形貌的影響。結果發現氧化銦奈米線不適合在載流氣體為氬氣和氧氣混合的情況下成長。即在實驗過程中額外的氧氣供應會不利於氧化銦奈米線成長。在此實驗基礎下我們接著探討不同成長溫度對氧化銦奈米線形貌的影響。從X射線繞射分析儀(XRD)的觀測結果發現奈米線的晶性隨著成長溫度上升而增加。另一方面由掃描式電子顯微鏡(SEM)的觀測下，我們發現線長隨著溫度的上升而增加。觀測結果顯示奈米線的品質在成長溫度為900℃為最好。
接著，我們探討不同成長溫度的氧化銦奈米線其光電化學反應活性，實驗結果顯示奈米線的品質與光電化學反應效率成正相關。經過計算，在成長溫度為800℃、850℃、900℃之氧化銦奈米線光電極在0伏特偏壓下其光電轉換效率分別為0.016%、 0.356% 以及1.222%。
最後，我們探討碳參雜之氧化銦奈米線對其光電化學反應效率的影響。以化學氣相沉積法進行碳參雜為一較不昂貴且簡單的參雜方式，另外，由X射線能量散佈儀(EDX)以及X射線光電子能譜儀(XPS)的分析可以確認奈米線內部有碳的成分以及含量。實驗結果發現無參雜以及碳參雜之氧化銦奈米線光電極在0伏特偏壓下其光電轉換效率分別為1.22% 以及 4.199%。其結果顯示經碳參雜後之氧化銦奈米線光電極可以有效提升光電化學反應效率，在水分解產氫上具備應用開發之潛力。

The main goal of this dissertation is the fabrication and analysis of highly photoactive In2O3 nanowires photoelectrode in photoelectrochemical (PEC) application. The In2O3 nanowires were grown using vapor-liquid-solid method on cost effective SiO2/Si template. The experiment is divided into three parts：
First, we investigate the relation between the oxygen flow rate and the morphologies of In2O3 nanostructures. The results show that indium oxide nanowires would not be preferable grown in Ar/O2 ambient. The extra supply of oxygen would be harmful to growing indium oxide nanowires. Based on the result, we then control the growth temperature and successfully synthesize different morphologies of In2O3 nanowires at different temperature without the extra supply of oxygen. It was found that XRD intensity increased as we increased the growth temperature. The observations suggest that the crystalline quality of the nanowires depend on the growth temperature.
In the second part of our experiment, we report the growth of In2O3 nanowires using a vapor phase transport method and the PEC hydrogen generation using these nanowires as PEC photoelectrode. It was found that crystallinity and PEC performances of the nanowires depend strongly on the growth temperature. It was also found that PEC conversion efficiencies were 0.016%, 0.356% and 1.222% at zero bias voltage (VCE) for the In2O3 nanowire samples prepared at 800oC, 850oC and 900oC, respectively.
Finally, we investigated the effect of C-doping on the photoelectrochemical properties of In2O3 nanowires prepared by vapor phase transport method. Vapor phase transport method offers an inexpensive and simple method to introduce carbon dopants into In2O3 nanowires by merely adding dopant sources to the indium source. The EDS and XPS confirmed carbon’s presence and content. It was found that PEC conversion efficiencies were 1.22% and 4.199% at zero bias voltage (VCE) for undoped and C-doped In2O3 nanowire samples, respectively. The results suggest that C-doped In2O3 nanowires shows highly enhanced PEC activity compared with undoped In2O3 nanowires.

Chapter 1

[1] S. S. Farvid and P. V. Radovanovic, "Phase Transformation of Colloidal In2O3 Nanocrystals Driven by the Interface Nucleation Mechanism: A Kinetic Study," Journal of the American Chemical Society, vol. 134, pp. 7015-7024, 2012.
[2] R. Shannon, "New high pressure phases having the corundum structure," Solid State Communications, vol. 4, pp. 629-630, 1966.
[3] A. Gurlo, P. Kroll, and R. Riedel, "Metastability of Corundum‐Type In2O3," Chemistry-a European Journal, vol. 14, pp. 3306-3310, 2008.
[4] A. Gurlo, N. Bârsan, M. Ivanovskaya, U. Weimar, and W. Göpel, "In2O3 and MoO3–In2O3 thin film semiconductor sensors: interaction with NO2 and O3," Sensors and Actuators B: Chemical, vol. 47, pp. 92-99, 4/30/ 1998.
[5] Y. Shigesato, S. Takaki, and T. Haranoh, "Electrical and structural properties of low resistivity tin‐doped indium oxide films," Journal of applied physics, vol. 71, pp. 3356-3364, 1992.
[6] Q. Liu, W. Lu, A. Ma, J. Tang, J. Lin, and J. Fang, "Study of quasi-monodisperse In2O3 nanocrystals: synthesis and optical determination," Journal of the American Chemical Society, vol. 127, pp. 5276-5277, 2005.
[7] S. Ju, A. Facchetti, Y. Xuan, J. Liu, F. Ishikawa, P. Ye, et al., "Fabrication of fully transparent nanowire transistors for transparent and flexible electronics," Nature Nanotechnology, vol. 2, pp. 378-384, 2007.
[8] C. Li, D. Zhang, X. Liu, S. Han, T. Tang, J. Han, et al., "In2O3 nanowires as chemical sensors," Applied Physics Letters, vol. 82, pp. 1613-1615, 2003.
[9] J. Gan, X. Lu, J. Wu, S. Xie, T. Zhai, M. Yu, et al., "Oxygen vacancies promoting photoelectrochemical performance of In2O3 nanocubes," Scientific reports, vol. 3, 2013.
[10] S. S. Farvid, N. Dave, T. Wang, and P. V. Radovanovic, "Dopant-induced manipulation of the growth and structural metastability of colloidal indium oxide nanocrystals," The Journal of Physical Chemistry C, vol. 113, pp. 15928-15933, 2009.

Chapter 2

[1] R. S. Wagner and W. C. Ellis, "VAPOR‐LIQUID‐SOLID MECHANISM OF SINGLE CRYSTAL GROWTH," Applied Physics Letters, vol. 4, pp. 89-90, 1964.
[2] A. Fujishima and K. Honda, “Electrochemical photolysis of water at a semiconductor electrode,” Nature, vol. 238, pp. 37-38, 1972.
[3] J. Gan, X. Lu, J. Wu, S. Xie, T. Zhai, M. Yu, et al., "Oxygen vacancies promoting photoelectrochemical performance of In2O3 nanocubes," Scientific reports, vol. 3, 2013
[4] M. Barroso, C. A. Mesa, S. R. Pendlebury, A. J. Cowan, T. Hisatomi, K. Sivula, et al., "Dynamics of photogenerated holes in surface modified α-Fe2O3 photoanodes for solar water splitting," Proceedings of the National Academy of Sciences, vol. 109, pp. 15640-15645, 2012.
[5] G. Xie, K. Zhang, B. Guo, Q. Liu, L. Fang, and J. R. Gong, "Graphene‐Based Materials for Hydrogen Generation from Light‐Driven Water Splitting," Advanced Materials, vol. 25, pp. 3820-3839, 2013
[6] Joseph Goldstein (2003). Scanning Electron Microscopy and X-Ray Microanalysis
[7] R. van de Krol, Y. Liang, and J. Schoonman, "Solar hydrogen production with nanostructured metal oxides," Journal of Materials Chemistry, vol. 18, pp. 2311-2320, 2008.

Chapter 3

[1] R. Weiher and R. Ley, "Optical properties of indium oxide," Journal of Applied Physics, vol. 37, pp. 299-302, 2004.
[2] Kim Y H, Kim W K and Han J J. Korean Phys. Soc. 491221,2006
[3] A. Gurlo, N. Barsan, U. Weimar, M. Ivanovskaya, A. Taurino, and P. Siciliano, "Polycrystalline well-shaped blocks of indium oxide obtained by the sol-gel method and their gas-sensing properties," Chemistry of materials, vol. 15, pp. 4377-4383, 2003.
[4] H. Jia, Y. Zhang, X. Chen, J. Shu, X. Luo, Z. Zhang, et al., "Efficient field emission from single crystalline indium oxide pyramids," Applied physics letters, vol. 82, pp. 4146-4148, 2003.
[5] C. Li, D. Zhang, S. Han, X. Liu, T. Tang, and C. Zhou, "Diameter‐Controlled Growth of Single‐Crystalline In2O3 Nanowires and Their Electronic Properties," Advanced Materials, vol. 15, pp. 143-146, 2003.
[6] N. Du, H. Zhang, B. Chen, X. Ma, Z. Liu, J. Wu, et al., "Porous Indium Oxide Nanotubes: Layer‐by‐Layer Assembly on Carbon‐Nanotube Templates and Application for Room‐Temperature NH3 Gas Sensors," Advanced Materials, vol. 19, pp. 1641-1645, 2007.
[7] A. Murali, A. Barve, V. J. Leppert, S. H. Risbud, I. M. Kennedy, and H. W. Lee, "Synthesis and characterization of indium oxide nanoparticles," Nano Letters, vol. 1, pp. 287-289, 2001.
[8] Y. Yan, Y. Zhang, H. Zeng, J. Zhang, X. Cao, and L. Zhang, "Tunable synthesis of In2O3 nanowires, nanoarrows and nanorods," Nanotechnology, vol. 18, p. 175601, 2007.
[9] N. Singh, T. Zhang, and P. S. Lee, "The temperature-controlled growth of In2O3 nanowires, nanotowers and ultra-long layered nanorods," Nanotechnology, vol. 20, p. 195605, 2009.
[10] O. Hayden, A. B. Greytak, and D. C. Bell, "Core–Shell Nanowire Light‐Emitting Diodes," Advanced Materials, vol. 17, pp. 701-704, 2005. [11] C. J. Chen, W. L. Xu, and M. Y. Chern, "Low‐Temperature Epitaxial Growth of Vertical In2O3 Nanowires on A‐Plane Sapphire with Hexagonal Cross‐Section," Advanced Materials, vol. 19, pp. 3012-3015, 2007.
[12] A. Klamchuen, T. Yanagida, M. Kanai, K. Nagashima, K. Oka, T. Kawai, et al., "Role of surrounding oxygen on oxide nanowire growth," Applied Physics Letters, vol. 97, p. 073114, 2010.
[13] S. Kodambaka, J. B. Hannon, R. M. Tromp, and F. M. Ross, "Control of Si nanowire growth by oxygen," Nano letters, vol. 6, pp. 1292-1296, 2006.

Chapter 4

[1] J. A. Turner, “A Realizable Renewable Energy Future,” Science, vol.285, pp. 687-689, 1999.
[2] N. S. Lewis and D. G. Nocera, “Powering the planet: Chemical challenges in solar energy utilization,” Proceedings of the National Academy of Sciences, vol. 103, pp. 15729-15735, 2006.
[3] M. G. Walter, E. L. Warren, J. R. McKone, S. W. Boettcher, Q. Mi, E. A. Santori and N. S. Lewis, “Solar Water Splitting Cells,” Chemical Reviews, vol. 110, pp. 6446-6473, 2010.
[4] T. Bak, J. Nowotny, M. Rekas, and C. C. Sorrell, “Photo-electrochemical hydrogen generation from water using solar energy. Materials-related aspects,” International Journal of hydrogen energy, vol. 27, pp. 991-1022, 2002.
[5] M. Ni, M. K. Leung, D. Y. Leung, and K. Sumathy, “A review and recent developments in photocatalytic water-splitting using TiO2 for hydrogen production,” Renewable and Sustainable Energy Reviews, vol. 11, pp. 401-425, 2007.
[6] A. Fujishima and K. Honda, “Electrochemical photolysis of water at a semiconductor electrode,” Nature, vol. 238, pp. 37-38, 1972.
[7] A. Kay, I. Cesar, and M. Gratzel, “New benchmark for water photooxidation by nanostructured alpha-Fe2O3 films” Journal of the American Chemical Society, vol.128, pp. 15714–15721, 2006.
[8] Y. Sun, C. J. Murphy, K. R. Reyes-Gil., E. A. Reyes-Garcia, J. P. Lilly, and D. Raftery, “Carbon-doped In2O3 films for photoelectrochemical hydrogen production” International Journal of Hydrogen Energy, vol.33, pp. 5967-5974, 2008.
[9] A. Hameed, M. Gondal, and Z. Yamani, “Effect of transition metal doping on photocatalytic activity of WO3 for water splitting under laser illumination: role of 3d-orbitals,” Catalysis Communications, vol. 5, pp. 715-719, 2004.
[10] K. Kakiuchi, E. Hosono, and S. Fujihara “Enhanced photoelectrochemical performance of ZnO electrodes sensitized with N-719,” Journal of Photochemistry and Photobiology A: Chemistry, vol. 179, pp. 81-86, 2006.
[11] C. Li, D. Zhang, X. Liu, S. Han, T. Tang, J. Han, et al., "In2O3 nanowires as chemical sensors," Applied Physics Letters, vol. 82, pp. 1613-1615, 2003.
[12] M. Curreli, C. Li, Y. Sun, B. Lei, M. A. Gundersen, M. E. Thompson, et al., "Selective functionalization of In2O3 nanowire mat devices for biosensing applications," Journal of the American Chemical Society, vol. 127, pp. 6922-6923, 2005.
[13] A. J. Nozik, "Photoelectrochemistry: Applications to solar energy conversion," Annual review of physical chemistry, vol. 29, pp. 189-222, 1978.
[14] R. Sharma, R. S. Mane, S.-K. Min, and S.-H. Han, "Optimization of growth of In2O3 nano-spheres thin films by electrodeposition for dye-sensitized solar cells," Journal of Alloys and Compounds, vol. 479, pp. 840-843, 2009.
[15] J. Shi, Y. Hara, C. Sun, M. A. Anderson, and X. Wang, “Three-dimensional high-density hierarchical nanowire architecture for high-performance photoelectrochemical electrodes,” Nano Lett., vol. 11, pp. 3413-3419, 2011.
[16] K. Shankar, J. I. Basham, N. K. Allam, O. K. Varghese, G. K. Mor, X. Feng, et al., “Recent advances in the use of TiO2 nanotube and nanowire arrays for oxidative photoelectrochemistry,” J. Phys. Chem. C, vol. 113, pp. 6327-6359, 2009.
[17] J. S. Hwang, T. Y. Liu, S. Chattopadhyay, G. M. Hsu, A. M. Basilio, H. W. Chen, Y. K. Hsu, W. H. Tu, Y. G. Lin, K. H. Chen, C. C. Li, S. B. Wang, H. Y. Chen, and L. C. Chen, “Growth of β-Ga2O3 and GaN nanowires on GaN for photoelectrochemical hydrogen generation,” Nanotechnol., vol. 24, Art. No. 055401, 2013.
[18] S. U. Khan, M. Al-Shahry, and W. B. Ingler, “Efficient photochemical water splitting by a chemically modified n-TiO2,” Science, vol. 297, pp. 2243-2245, 2002.
[19] Y. Sun, C. J. Murphy, K. R. Reyes-Gil, E. A. Reyes-Garcia, J. P. Lilly, and D. Raftery, "Carbon-doped In2O3 films for photoelectrochemical hydrogen production," International Journal of Hydrogen Energy, vol. 33, pp. 5967-5974, 2008

Chapter 5

[1] P. Nguyen, H. T. Ng, T. Yamada, M. K. Smith, J. Li, J. Han, et al., "Direct integration of metal oxide nanowire in vertical field-effect transistor," Nano Letters, vol. 4, pp. 651-657, 2004.
[2] H. Wang and J. Lewis, "Second-generation photocatalytic materials: anion-doped TiO2," Journal of Physics: Condensed Matter, vol. 18, p. 421, 2006.
[3] C. Xu and S. U. Khan, "Photoresponse of visible light active carbon-modified-n-TiO2 thin films," Electrochemical and solid-state letters, vol. 10, pp. B56-B59, 2007.
[4] F. Gracia, J. Holgado, A. Caballero, and A. Gonzalez-Elipe, "Structural, Optical, and Photoelectrochemical Properties of Mn+-TiO2 Model Thin Film Photocatalysts," The Journal of Physical Chemistry B, vol. 108, pp. 17466-17476, 2004.
[5] S. Klosek and D. Raftery, "Visible light driven V-doped TiO2 photocatalyst and its photooxidation of ethanol," The Journal of Physical Chemistry B, vol. 105, pp. 2815-2819, 2001.
[6] K. Madhusudan Reddy, B. Baruwati, M. Jayalakshmi, M. Mohan Rao, and S. V. Manorama, "S-, N-and C-doped titanium dioxide nanoparticles: synthesis, characterization and redox charge transfer study," Journal of Solid State Chemistry, vol. 178, pp. 3352-3358, 2005.
[7] S. Sakthivel, M. Janczarek, and H. Kisch, "Visible light activity and photoelectrochemical properties of nitrogen-doped TiO2," The Journal of Physical Chemistry B, vol. 108, pp. 19384-19387, 2004.
[8] T. Umebayashi, T. Yamaki, H. Itoh, and K. Asai, "Band gap narrowing of titanium dioxide by sulfur doping," Applied Physics Letters, vol. 81, pp. 454-456, 2002.
[9] M. Janus, M. Inagaki, B. Tryba, M. Toyoda, and A. Morawski, "Carbon-modified TiO2 photocatalyst by ethanol carbonisation," Applied Catalysis B: Environmental, vol. 63, pp. 272-276, 2006.
[10] Y. Sun, C. J. Murphy, K. R. Reyes-Gil, E. A. Reyes-Garcia, J. P. Lilly, and D. Raftery, "Carbon-doped In2O3 films for photoelectrochemical hydrogen production," International Journal of Hydrogen Energy, vol. 33, pp. 5967-5974, 2008.
[11] B. Li, Y. Xie, M. Jing, G. Rong, Y. Tang, and G. Zhang, "In2O3 hollow microspheres: synthesis from designed In(OH)3 precursors and applications in gas sensors and photocatalysis," Langmuir, vol. 22, pp. 9380-9385, 2006.
[12] A. Nelson and H. Aharoni, "X‐ray photoelectron spectroscopy investigation of ion beam sputtered indium tin oxide films as a function of oxygen pressure during deposition," Journal of Vacuum Science & Technology A, vol. 5, pp. 231-233, 1987.
[13] S. Y. Li, C. Y. Lee, P. Lin, and T. Y. Tseng, "Low temperature synthesized Sn doped indium oxide nanowires," Nanotechnology, vol. 16, p. 451, 2005.
[14] S. U. Khan, M. Al-Shahry, and W. B. Ingler, "Efficient photochemical water splitting by a chemically modified n-TiO2," Science, vol. 297, pp. 2243-2245, 2002.
[15] H. Irie, Y. Watanabe, and K. Hashimoto, "Carbon-doped anatase TiO2 powders as a visible-light sensitive photocatalyst," Chemistry Letters, pp. 772-773, 2003.
[16] W. Ren, Z. Ai, F. Jia, L. Zhang, X. Fan, and Z. Zou, "Low temperature preparation and visible light photocatalytic activity of mesoporous carbon-doped crystalline TiO2," Applied Catalysis B: Environmental, vol. 69, pp. 138-144, 2007.
[17] T. Tachikawa, S. Tojo, K. Kawai, M. Endo, M. Fujitsuka, T. Ohno, et al., "Photocatalytic oxidation reactivity of holes in the sulfur-and carbon-doped TiO2 powders studied by time-resolved diffuse reflectance spectroscopy," The Journal of Physical Chemistry B, vol. 108, pp. 19299-19306, 2004.
[18] S. Sakthivel and H. Kisch, "Daylight photocatalysis by carbon‐modified titanium dioxide," Angewandte Chemie International Edition, vol. 42, pp. 4908-4911, 2003.
[19] R. Nakamura, T. Tanaka, and Y. Nakato, "Mechanism for visible light responses in anodic photocurrents at N-doped TiO2 film electrodes," The Journal of Physical Chemistry B, vol. 108, pp. 10617-10620, 2004.
 
Chapter 6

[1] Y. Sun, C. J. Murphy, K. R. Reyes-Gil, E. A. Reyes-Garcia, J. P. Lilly, and D. Raftery, "Carbon-doped In2O3 films for photoelectrochemical hydrogen production," International Journal of Hydrogen Energy, vol. 33, pp. 5967-5974, 2008.
[2] H. M. Chen, C. K. Chen, C.-J. Chen, L.-C. Cheng, P. C. Wu, B. H. Cheng, et al., "Plasmon inducing effects for enhanced photoelectrochemical water splitting: X-ray absorption approach to electronic structures," ACS nano, vol. 6, pp. 7362-7372, 2012.
[3] Y.-C. Pu, G. Wang, K.-D. Chang, Y. Ling, Y.-K. Lin, B. C. Fitzmorris, et al., "Au Nanostructure-Decorated TiO2 Nanowires Exhibiting Photoactivity Across Entire UV-visible Region for Photoelectrochemical Water Splitting," Nano letters, vol. 13, pp. 3817-3823, 2013.