二氧化鈰奈米粒子被廣泛應用在光催化、固態氧化燃料電池、三元觸媒轉換器，和有機催化中。目前已發表的論文中皆使用高濃度的氫氧化鈉在高溫環境下以長時間合成正立方體的二氧化鈰奈米粒子。在此研究中，我們利用濃度較低的氨水與硫酸鈉在100°C反應5小時得到尺寸均勻的正立方體二氧化鈰奈米粒子，加入硫酸鈉可在反應過程中產生白色的硫酸鈰中間產物，以此來控制反應速率，進而調整奈米粒子的形狀，並藉由改變前驅物的濃度與反應溫度來合成特定尺寸(9、13、18 nm)的正立方體二氧化鈰奈米粒子。
透過吸收光譜可觀察到隨著奈米粒子的尺寸增加，吸收光譜的鋒值紅位移。由此我們得知當奈米粒子的尺寸超過其波爾半徑時，仍然可觀察到光譜的位移，這一現象刷新了我們對於量子侷限的認知。進一步將不同尺寸的正立方體二氧化鈰奈米粒子之吸收光譜，與之前製備的正八面體二氧化鈰奈米粒子之吸收光譜對照之下，可發現在同一尺寸但不同晶面之奈米粒子有不同的吸收。上述現象證明了光學上的尺寸與晶面效應。在電化學量測中，透過莫特-肖特基量測可以發現尺寸效應對導帶與價帶能階的影響。透過電化學產氧的量測,可發現尺寸效應造成的導帶位置不同對產氧的電位會有影響。

Ceria nanoparticles can be applied in photocatalysis, solid oxide fuel cell (SOFC), three-way catalysts (TWCs), and organic catalysis. A very concentrated base and high temperature are normally employed to make CeO2 particles. In this research, mild synthesis of 1-bound cubic ceria nanoparticles with tunable sizes has been developed by heating cerium(III) nitrate hexahydrate, sodium sulfate, and dilute ammonia at 100 ºC for 4 hours. Adding sodium sulfate can produce a white precipitate, Ce2(SO4)3, which possibly reduces the rate of reaction to yield CeO2 nano-cubes with sizes of 9, 13, and 18 nm. The maximum absorption wavelength red-shifts as the size of ceria nanoparticles increases. Comparing to the {111}-bound CeO2 octahedra of similar volume with a band gap of 3.46 eV, the 18 nm CeO2 cubes show a band gap of 3.45 eV. This equates to a band wavelength separation of about 10 nm. Thus, CeO2 nanocrystals exhibit both optical size and facet effects. From Mott–Schottky measurements, the energy levels of conduction band and valence band show size dependence. Notably, the size-dependent valence band energy difference gives onset potential variation in the electrochemical oxygen evolution reaction.

論文摘要 I
ABSTRACT II
ACKNOWLEDGEMENT III
LIST OF CONTENT IV
LIST OF FIGURES VI
LIST OF SCHEMES IX
LIST OF TABLES X
1. Literature review 1
1.1. CeO2 (Ceria) 5
1.2. Applications 5
1.3. Synthesis of CeO2 nanoparticles 7
1.4. Synthesis of CeO2 nanoparticles in organic system 9
1.5. Synthesis of CeO2 nanoparticle in aqua system 13
2. Synthesis of CeO2 cubes to demonstrate the size effect 18
3 Experimental Section 20
3.1 Reagents & Instrumentation 20
3.2 Synthesis of CeO2 nanocubes 21
3.3 Electrochemical measurements 22
3.3.1 Mott−Schottky Measurements 22
3.3.2 Oxygen Evolution Reaction Measurements 22
4 Results and Discussion 23
4.1 Characterization of CeO2 nanocubes 23
4.1.1 Scanning electron microscopy 23
4.1.2 Transmission electron microscopy 23
4.1.3 Powder X-ray diffraction 25
4.2 Plausible reaction mechanism of CeO2 cubes 25
4.3 Size& facet-dependentoptical properties 28
4.4 Size-dependent variation of conduction band 30
4.5 Size-dependent variation of onset OER potentials 34
5 Conclusion 35
6 References 37

Chung, P.-J.; Lyu, L.-M.; Huang, M. H. Seed-Mediated and Iodide-Assisted Synthesis of Gold Nanocrystals with Systematic Shape Evolution from Rhombic Dodecahedral to Octahedral Structures. Chem.-Eur. J. 2011, 17, 9746‒9752.
2. Hsia, C.-F.; Madasu, M.; Huang, M. H. Aqueous Phase Synthesis of Au–Cu Core–Shell Nanocubes and Octahedra with Tunable Sizes and Noncentrally Located Cores. Chem. Mater. 2016, 28, 3073‒3079.
3. Hsieh, M.-S.; Su, H.-J.; Hsieh, P.-L.; Chiang, Y.-W.; Huang, M. H. Synthesis of Ag3PO4 Crystals with Tunable Shapes for Facet-Dependent Optical Property, Photocatalytic Activity, and Electrical Conductivity Examinations. ACS Appl. Mater. Interfaces 2017, 9, 39086‒39093.
4. Kuo, C.-H.; Huang, M. H. Facile Synthesis of Cu2O Nanocrystals with Systematic Shape Evolution from Cubic to Octahedral Structures. J. Phys. Chem. C 2008, 112, 18355‒18360.
5. Lyu, L. M.; Wang, W. C.; Huang, M. H. Synthesis of Ag2O Nanocrystals with Systematic Shape Evolution from Cubic to Hexapod Structures and Their Surface Properties. Chem.-Eur. J. 2010, 16, 14167‒14174.
6. Chen, Y.-J.; Chiang, Y.-W.; Huang, M. H. Synthesis of Diverse Ag2O Crystals and Their Facet-Dependent Photocatalytic Activity Examination. ACS Appl. Mater. Interfaces 2016, 8, 19672‒19679.
7. Huang, W.-C.; Lyu, L.-M.; Yang, Y.-C.; Huang, M. H. Synthesis of Cu2O Nanocrystals from Cubic to Rhombic Dodecahedral Structures and Their Comparative Photocatalytic Activity. J. Am. Chem. Soc. 2012, 134, 1261‒1267.
8. Tan, C.-S.; Chen, Y.-J.; Hsia, C.-F.; Huang, M. H. Facet‐Dependent Electrical Conductivity Properties of Silver Oxide Crystals. Chem Asian J. 2017, 12, 293‒297.
9. Tan, C.-S.; Hsu, S.-C.; Ke, W.-H.; Chen, L.-J.; Huang, M. H. Facet-Dependent Electrical Conductivity Properties of Cu2O Crystals. Nano Lett. 2015, 15, 2155-2160.
10. Tan, C.-S.; Hsieh, P.-L.; Chen, L.-J.; Huang, M. H. Silicon Wafers with Facet-Dependent Electrical Conductivity Property. Angew. Chem. Int. Ed. 2017, 129, 15541‒15545.
11. Hsieh, P.-L.; Naresh, G.; Huang, Y.-S.; Tsao, C.-W.; Hsu, Y.-J.; Chen, L.-J.; Huang, M. H. Shape-Tunable SrTiO3 Crystals Revealing Facet-Dependent Optical and Photocatalytic Properties. J. Phys. Chem. C 2019, 123, 13664‒13671.
12. Ke, W.-H.; Hsia, C.-F.; Chen, Y.-J.; Huang, M. H. Synthesis of Ultrasmall Cu2O Nanocubes and Octahedra with Tunable Sizes for Facet‐Dependent Optical Property Examination. Small 2016, 12, 3530‒3534.
13. Thoks, S.; Lee, A.-T. Huang, M. H. Scalable Synthesis of Size-Tunable Small Cu2O Cubes and Octahedra for Facet-Dependent Optical Characterization and Pseudomorphic Conversion to Cu Nanocrystals. ACS Sustainable Chem. Eng. 2019, 7, 10467–10476.
14. Huang, J.-Y.; Madasu, M.; Huang, M. H. Modified Semiconductor Band Diagrams Constructed from Optical Characterization of Size-Tunable Cu2O Cubes, Octahedra, and Rhombic Dodecahedra. J. Phys. Chem. C 2018, 122, 13027‒13033.
15. Huang, Y.-C.; Wu, S.-H.; Hsiao, C.-H.; Lee, A.-T.; Huang, M. H. Mild Synthesis of Size-Tunable CeO2 Octahedra for Band Gap Variation. Chem. Mater. 2020, 32, 2631‒2638.
16. Majumder, D.; Chakraborty, I.; Mandal, K.; Roy, S. Facet-Dependent Photodegradation of Methylene Blue Using Pristine CeO2 Nanostructures. ACS Omega 2019, 4, 4243‒4251.
17. Samiee, S.; Goharshadi, E. K. Effects of Different Precursors on Size and Optical Properties of Ceria Nanoparticles Prepared by Microwave-Assisted Method. Mater. Res. Bull 2012, 47, 1089‒1095.
18. Wu, T.-S.; Syu, L.-Y.; Lin, C.-N.; Lin, B.-H.; Liao, Y.-H.; Weng, S.-C.; Huang, Y.-J.; Jeng, H.-T.; Lu, S.-Y.; Chang, S.-L. Enhancement of Catalytic Activity by Uv-Light Irradiation in CeO2 Nanocrystals. Sci. Rep. 2019, 9, 8018.
19. Amrute, A. P.; Mondeli, C.; Moser, M.; Novell-Leruth, G.; López, N.; Rosenthal, D.; Farra, R.; Schuster, E. M.; Teschner, D.; Schmidt, T.; Pérez-Ramírez, J. Performance, Structure, and Mechanism of CeO2 in HCl Oxidation to Cl2. J. Catal. 2012, 286, 287‒297.
20. Kašpar, J.; Fornasiero, P.; Graziani, M. Use of CeO2-Based Oxides in the Three-Way Catalysis. Catal. Today 1999, 50, 285‒298.
21. Kašpar, J.; Fornasiero, P.; Hickey, N. Automotive Catalytic Converters: Current Status and Some Perspectives. Catal. Today 2003, 77, 419‒449.
22. Kim, H. Y.; Lee, H. M.; Henkelman, G. Co Oxidation Mechanism on CeO2-Supported Au Nanoparticles. J. Am. Chem. Soc. 2012, 134, 1560‒70.
23. Li, C.; Sun, Yu.; Djerdj, I.; Voepel, P.; Sack, C.-C.; Weller, T.; Ellinghaus, R.; Sann, J.; Guo, Y.; Smarsly, M.B.; Over, H. Shape-Controlled CeO2 Nanoparticles: Stability and Activity in the Catalyzed HCl Oxidation Reaction. ACS Catal. 2017, 7, 6453‒6463.
24. Mukherjee, D.; Reddy, B. M. Noble Metal-Free CeO2-Based Mixed Oxides for Co and Soot Oxidation. Catal. Today 2018, 309, 227‒235.
25. Wang, Z.; Qu, Z.; Quan, X.; Li, Z.; Wang, H.; Fan, R. Selective Catalytic Oxidation of Ammonia to Nitrogen over CuO-CeO2 Mixed Oxides Prepared by Surfactant-Templated Method. Appl. Catal. B 2013, 134‒135, 153‒166.
26. Wu, Z.; Li, M.; Overbury, S. H. On the Structure Dependence of Co Oxidation over CeO2 Nanocrystals with Well-Defined Surface Planes. J. Catal. 2012, 285, 61‒73.
27. Zhang, J.; Kumagai, H.; Yamamura, K.; Ohara, S.; Takami, S.; Morikawa, A.; Shinjoh, H.; Kaneko, K.; Adschiri, T.; Suda, A. Extra-Low-Temperature Oxygen Storage Capacity of CeO2 Nanocrystals with Cubic Facets. Nano Lett. 2011, 11, 361‒364.
28. Farra, R.; Eichelbaum, M.; Schlögl, R.; Szentmiklósi, L.; Schmidt, T.; Amrute, A. P.; Mondelli, C.; Pérez-Ramírez, J.; Teschner, D. Do Observations on Surface Coverage-Reactivity Correlations Always Describe the True Catalytic Process? A Case Study on Ceria. J. Catal. 2013, 297, 119‒127.
29. Amrute, A. P.; Mondelli, C.; Moser, M.; Novell-Leruth, G.; López, N.; Rosenthal, D.; Farra, R.; Schuster, M. E.; Teschner, D.; Schmidt, T. Performance, Structure, and Mechanism of CeO2 in Hcl Oxidation to Cl2. J. Catal. 2012, 286, 287‒297.
30. Snell, R. W.; Shanks, B. H. Insights into the Ceria-Catalyzed Ketonization Reaction for Biofuels Applications. ACS Catal. 2013, 3, 783‒789.
31. Leyva-Pérez, A.; Cómbita-Merchán, D.; Cabrero-Antonino, J. R.; Al-Resayes, S. I.; Corma, A. Oxyhalogenation of Activated Arenes with Nanocrystalline Ceria. ACS Catal. 2013, 3, 250‒258.
32. Nelson, N. C.; Manzano, J. S.; Sadow, A. D.; Overbury, S. H.; Slowing, I. I. Selective Hydrogenation of Phenol Catalyzed by Palladium on High-Surface-Area Ceria at Room Temperature and Ambient Pressure. ACS Catal. 2015, 5, 2051‒2061.
33. Asati, A.; Kaittanis, C.; Santra, S.; Perez, J. M. Ph-Tunable Oxidase-Like Activity of Cerium Oxide Nanoparticles Achieving Sensitive Fluorigenic Detection of Cancer Biomarkers at Neutral Ph. Anal. Chem. 2011, 83, 2547‒2553.
34. Asati, A.; Santra, S.; Kaittanis, C.; Nath, S.; Perez, J. M. Oxidase‐Like Activity of Polymer‐Coated Cerium Oxide Nanoparticles. Angew. Chem. Int. Ed. 2009, 48, 2308‒2312.
35. Li, X.; Sun, L.; Ge, A.; Guo, Y. Enhanced Chemiluminescence Detection of Thrombin Based on Cerium Oxide Nanoparticles. Chem. Comm. 2011, 47, 947‒949.
36. Celardo, I.; Pedersen, J. Z.; Traversa, E.; Ghibelli, L. Pharmacological Potential of Cerium Oxide Nanoparticles. Nanoscale 2011, 3, 1411‒1420.
37. Li, M.; Shi, P.; Xu, C.; Ren, J.; Qu, X. Cerium Oxide Caged Metal Chelator: Anti-Aggregation and Anti-Oxidation Integrated H2O2-Responsive Controlled Drug Release for Potential Alzheimer's Disease Treatment. Chem. Sci. 2013, 4, 2536‒2542.
38. Xu, C.; Lin, Y.; Wang, J.; Wu, L.; Wei, W.; Ren, J.; Qu, X. Nanoceria‐Triggered Synergetic Drug Release Based on CeO2‐Capped Mesoporous Silica Host–Guest Interactions and Switchable Enzymatic Activity and Cellular Effects of CeO2. Adv. Health Mater. 2013, 2, 1591‒1599.
39. Chang, H.-Y.; Chen, H.-I. Morphological Evolution for CeO2 Nanoparticles Synthesized by Precipitation Technique. J. Cryst. Growth 2005, 283, 457‒468.
40. Chen, H.-I.; Chang, H.-Y. Synthesis of Nanocrystalline Cerium Oxide Particles by the Precipitation Method. Ceram. Int. 2005, 31, 795‒802.
41. Li, J. G.; Ikegami, T.; Wang, Y.; Mori, T. Reactive Ceria Nanopowders Via Carbonate Precipitation. J. Am. Ceram. Soc. 2002, 85, 2376‒2378.
42. Kaneko, K.; Inoke, K.; Freitag, B.; Hungria, A. B.; Midgley, P. A.; Hansen, T. W.; Zhang, J.; Ohara, S.; Adschiri, T. Structural and Morphological Characterization of Cerium Oxide Nanocrystals Prepared by Hydrothermal Synthesis. Nano Lett. 2007, 7, 421‒425.
43. Guo, Z.; Du, F.; Li, G.; Cui, Z. Synthesis and Characterization of Single-Crystal Ce (OH) CO3 and CeO2 Triangular Microplates. Inorg. Chem. 2006, 45, 4167‒4169.
44. Li, C.; Sun, Q.; Lu, N.; Chen, B.; Dong, W. A Facile Route for the Fabrication of CeO2 Nanosheets Via Controlling the Morphology of CeOHCO3 Precursors. J. Cryst. Growth 2012, 343, 95‒100.
45. Yang, R.; Guo, L. Synthesis of Cubic Fluorite CeO2 Nanowires. J. Mater. Sci. 2005, 40, 1305‒1307.
46. Chen, G.; Sun, S.; Sun, X.; Fan, W.; You, T. Formation of CeO2 Nanotubes from Ce(OH)CO3 Nanorods through Kirkendall Diffusion. Inorg. Chem. 2009, 48, 1334‒1338.
47. Chen, G.; Zhu, F.; Sun, X.; Sun, S.; Chen, R. Benign Synthesis of Ceria Hollow Nanocrystals by a Template-Free Method. CrystEngComm 2011, 13, 2904‒2908.
48. Han, W.-Q.; Wu, L.; Zhu, Y. Formation and Oxidation State of CeO2-X Nanotubes. J. Am. Chem. Soc. 2005, 127, 12814‒12815.
49. Nguyen, T.-D.; Dinh, C.-T.; Do, T.-O. A General Procedure to Synthesize Highly Crystalline Metal Oxide and Mixed Oxide Nanocrystals in Aqueous Medium and Photocatalytic Activity of Metal/Oxide Nanohybrids. Nanoscale 2011, 3, 1861‒1873.
50. Yan, Z.-G.; Yan, C.-H. Controlled Synthesis of Rare Earth Nanostructures. J. Mater. Chem. 2008, 18, 5046‒5059.
51. Zhang, G.; Shen, Z.; Liu, M.; Guo, C.; Sun, P.; Yuan, Z.; Li, B.; Ding, D.; Chen, T. Synthesis and Characterization of Mesoporous Ceria with Hierarchical Nanoarchitecture Controlled by Amino Acids. J. Phys. Chem. B 2006, 110, 25782‒25790.
52. Lu, X.-h.; Huang, X.; Xie, S.-l.; Zheng, D.-z.; Liu, Z.-q.; Liang, C.-l.; Tong, Y.-X. Facile Electrochemical Synthesis of Single Crystalline CeO2 Octahedrons and Their Optical Properties. Langmuir 2010, 26, 7569‒7573.
53. Bao, H.; Zhang, Z.; Hua, Q.; Huang, W. Compositions, Structures, and Catalytic Activities of CeO2@Cu2O Nanocomposites Prepared by the Template-Assisted Method. Langmuir 2014, 30, 6427‒6436.
54. Chen, H.-I.; Chang, H.-Y. Homogeneous Precipitation of Cerium Dioxide Nanoparticles in Alcohol/Water Mixed Solvents. Colloids Surf. A Physicochem. Eng. Asp. 2004, 242, 61‒69.
55. Yang, S.; Gao, L. Controlled Synthesis and Self-Assembly of CeO2 Nanocubes. J. Am. Chem. Soc. 2006, 128, 9330‒9331.
56. Zhang, J.; Ohara, S.; Umetsu, M.; Naka, T.; Hatakeyama, Y.; Adschiri, T. Colloidal Ceria Nanocrystals: A Tailor‐Made Crystal Morphology in Supercritical Water. Adv. Mater. 2007, 19, 203‒206.
57. Mai, H.-X.; Sun, L.-D.; Zhang, Y.-W.; Si, R.; Feng, W.; Zhang, H.-P.; Liu, H.-C.; Yan, C.-H. Shape-Selective Synthesis and Oxygen Storage Behavior of Ceria Nanopolyhedra, Nanorods, and Nanocubes. J. Phys. Chem. B 2005, 109, 24380‒24385.
58. Piumetti, M.; Bensaid, S.; Andana, T.; Dosa, M.; Novara, C.; Giorgis, F.; Russo, N.; Fino, D. Nanostructured Ceria-Based Materials: Effect of the Hydrothermal Synthesis Conditions on the Structural Properties and Catalytic Activity. Catalysts 2017, 7, 174.
59. Pan, C.; Zhang, D.; Shi, L. Ctab Assisted Hydrothermal Synthesis, Controlled Conversion and Co Oxidation Properties of CeO2 Nanoplates, Nanotubes, and Nanorods. J. Solid State Chem. 2008, 181, 1298‒1306.
60. Yan, L.; Yu, R.; Chen, J.; Xing, X. Template-Free Hydrothermal Synthesis of CeO2 Nano-Octahedrons and Nanorods: Investigation of the Morphology Evolution. Cryst. Growth Des. 2008, 8, 1474‒1477.
61. Huang, M. H.; Naresh, G.; Chen, H.-S. Facet-Dependent Electrical, Photocatalytic, and Optical Properties of Semiconductor Crystals and Their Implications for Applications. ACS Appl. Mater. Interfaces 2018, 10, 4‒15.
62. Tan, C.-S.; Huang, M. H. Metal-Like Band Structures of Ultrathin Si {111} and {112} Surface Layers Revealed through Density Functional Theory Calculations. Chem.-Eur. J. 2017, 23, 11866‒11871.
63. Tan, C.-S.; Huang, M. H. Density Functional Theory Calculations Revealing Metal‐Like Band Structures and Work Function Variation for Ultrathin Gallium Arsenide (111) Surface Layers. Chem. Asian J 2019, 14, 2316‒2321.
64. Thoka, S.; Lee, A.-T.; Huang, M. H. Scalable Synthesis of Size-Tunable Small Cu2O Nanocubes and Octahedra for Facet-Dependent Optical Characterization and Pseudomorphic Conversion to Cu Nanocrystals. ACS Sustainable Chem. Eng. 2019, 7, 10467‒10476.
65. Li, G.-R.; Qu, D.-L.; Arurault, L.; Tong, Y.-X. Hierarchically Porous Gd3+-Doped CeO2 Nanostructures for the Remarkable Enhancement of Optical and Magnetic Properties. J. Phys. Chem. C 2009, 113, 1235‒1241.