在我的研究中，有別於絕大多數二氧化鈰合成方法是在高溫、長時間且是鹼性條件下合成，我藉由以水和乙醇形成共同溶劑的方式，以簡單的製程以及極短的時間合成出二氧化鈰的八面體奈米粒子，並在實驗中以控制前驅物濃度的方式達到奈米粒子尺寸之調控。
藉由量測可調控尺寸的二氧化鈰八面體奈米粒子的吸收以及放光光譜，發現其吸收及放光位置均會隨奈米粒子的尺寸增加而紅位移，證明了光學上的尺寸效應。顯然一個奈米粒子尺寸在遠大於材料的波耳半徑所計算的體積時，仍然可以藉由尺寸來調控能帶的現象，打破了一般人對於量子侷限效應的迷思。藉由電化學量測得到莫特-肖特基圖搭配莫特-肖特基方程式，可以用來計算不同尺寸二氧化鈰材料的導帶能量，來探索尺寸效應對二氧化鈰八面體的導帶能量的影響，並以尺寸效應對能帶圖做出更精準的修正。

Different from most synthetic strategies which have involved basicity, high temperature and ultralong reaction time, we have developed a synthetic method to grow CeO2 octahedra that can greatly shorten the reaction time without adding a base. By using water and ethanol as co-solvent, a series of size-tunable CeO2 octahedra with controlled sizes from 50 nm to 110 nm have been synthesized by simply tuning the amount of Ce(NO3)3 used. The reaction is also dramatically reduced to within 1 h.
Both light absorption and emission spectra of these particles showed red-shifts with increasing particle sizes, demonstrating size-dependent optical properties. Although the dimensions of the synthesized particles greatly exceed the volume calculated by Bohr radius of CeO2, band gap is still tunable. Clearly, the known concept of quantum confinement is incorrect. By Mott-Schottky measurements and Mott-Schottky equations, conduction band positions can be obtained to construct a new band diagram of CeO2 with respect to particle size.

1.Arul, N. S.; Mangalaraj, D.; Han, J. I. Facile hydrothermal synthesis of CeO2 nanopebbles. Bull. Mater. Sci. 2015, 38, 1135–1139.
2.Montini, T.; Melchionna, M.; Monai, M.; Fornasiero, P. Fundamentals and catalytic applications of CeO2‑based materials. Chem. Rev. 2016, 116, 5987–6041.
3.Younis, A.; Chu, D.; Li, S. Cerium oxide nanostructures and their applications. Functionalized Nanomaterials. InTech Open: Croatia, 2016, 52–68.
4.Ansari, S. A.; Khan, M. M.; Ansari, M. O.; Kalathil, S.; Leea, J.; Cho, M. H. Band gap engineering of CeO2 nanostructure using an electrochemically active biofilm for visible light applications. RSC Adv. 2014, 4, 16782–16791.
5.Li, H.; Fang, R.; Wang, Z.; Cheng, Z.; Han, T.; Li, M. Template-free hydrothermal synthesis and excellent optical performances of monodisperse tyre-like CeO2 hollow nanostructures with rugged surface. J. Mater. Sci.: Mater. Electron. 2018, 29, 1517–1522.
6.Guo, M.; Lu, J.; Wu, Y.; Wang, Y.; Luo, M. UV and visible Raman studies of oxygen vacancies in rare-earth-doped ceria. Langmuir 2011, 27, 3872–3877.
7.Kašpar, J.; Fornasiero, P.; Hickey, N. Automotive catalytic converters: Current status and some perspectives. Catal. Today 2003, 77, 419–449.
8.Kašpar, J.; Fornasiero, P.; Graziani, M. Use of CeO2-based oxides in the three-way catalysis. Catal. Today 1999, 50, 285–298.
9.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.
10.Mukherjee, D.; Reddy, B. M. Noble metal-free CeO2-based mixed oxides for CO and soot oxidation. Catal. Today 2018, 309, 227–235.
11.Chueh, W. C.; Hao, Y.; Jung, W.C.; Haile, S. H. High electrochemical activity of the oxide phase in model ceria–Pt and ceria–Ni composite anodes. Nat. Mater. 2012, 11, 155–161.
12.Thangadurai, V.; Weppner, W. Recent progress in solid oxide and lithium ion conducting electrolytes research. Ionics 2006, 12, 81–92.
13.Hernández-Alonso, M. D.; Hungría, A. B.; Martínez-Arias, A.; Fernández-García, M.; Coronado, J. M.; Conesa, J. S.; Soria, J. EPR study of the photoassisted formation of radicals on CeO2 nanoparticles employed for toluene photooxidation. Appl. Catal., B 2004, 50, 167–175.
14.Aslama, M.; Qamar, M. T.; Soomroa, M. T.; Ismail, I. M. I.; Salahc, N. Almeelbi, T.; Gondal, M. A.; Hameed, A. The effect of sunlight induced surface defects on the photocatalytic activity of nanosized CeO2 for the degradation of phenol and its derivatives. Appl. Catal., B 2016, 180, 391–402.
15.Mann, A. K. P.; Wu, Z.; Calaza, F. C.; Overbury, S. H. Adsorption and reaction of acetaldehyde on shape-controlled CeO2 nanocrystals: Elucidation of structure−function relationships. ACS Catal. 2014, 4, 2437–2448.
16.Wang, X.; Wu, J.; Wang, J.; Xiao, H.; Chen, B.; Peng, R.; Fu, M.; Chen, L.; Ye, D.; Wen, W. Methanol plasma-catalytic oxidation over CeO2 catalysts: Effect of ceria morphology and reaction mechanism. Chem. Eng. J. 2019, 369, 233–244.
17.Afzal, S.; Quan, X.; Lu, S. Catalytic performance and an insight into the mechanism of CeO2 nanocrystals with different exposed facets in catalytic ozonation of p-nitrophenol. Appl. Catal., B 2019, 248, 526–537.
18.Machida, M.; Murata, Y.; Kishikawa, K.; Zhang, D.; Ikeue, K. On the reasons for high activity of CeO2 catalyst for soot oxidation. Chem. Mater. 2008, 20, 4489–4494.
19.Laberty-Robert, C.; Long, J. W.; Lucas, E. M.; Pettigrew, K. A.; Stroud, R. M.; Doescher, M.S.; Rolison, D. R. Sol-gel-derived ceria nanoarchitectures: Synthesis, characterization, and electrical properties. Chem. Mater. 2006, 18, 50–58.
20.Calvache-Muñoz, J.; Prado, F. A.; Rodríguez-Páez, J. E. Cerium oxide nanoparticles: Synthesis, characterization and tentative mechanism of particle formation. Colloids Surf. A 2017, 529, 146–159.
21.Bumajdad, A.; Eastoe, J.; Mathewa, A. Cerium oxide nanoparticles prepared in self-assembled systems. Adv. Colloid Interface Sci. 2009, 147, 56–66.
22.Lu, X.-H.; Huang, X.; Xie, X.-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.
23.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.
24.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.
25.Mai, H.-X.; Sun, L.-D.; Zhang, Y.-W.; Si, R.; Feng, W.; Zhang, H.-P.; Liu, C.-H.; Yan, C.-H. Shape-selective synthesis and oxygen storage behavior of ceria nanopolyhedra, nanorods, and nanocubes. J. Phys. Chem. B 2005, 109, 24380–24385.
26.Piumetti, M.; Bensaid, S.; Andana, A.; 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.
27.Li, P.; Zhou, Y.; Zhao, Z.; Xu, Q.; Wang, X.; Xiao, M.; Zou, Z. Hexahedron prism-anchored octahedronal CeO2: Crystal facet-based homojunction promoting efficient solar fuel synthesis. J. Am. Chem. Soc. 2015, 137, 9547–9550.
28.Yang, S.; Gao, L. Controlled synthesis and self-assembly of CeO2 nanocubes. J. Am. Chem. Soc. 2006, 128, 9330–9331.
29.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.
30.Rej, S.; Wang, H.-J.; Huang, M.-X.; Hsu, S.-C.; Tan, C.-S.; Lin, F.-C.; Huang, J.-S.; Huang, M. H. Facet-dependent optical properties of Pd–Cu2O core–shell nanocubes and octahedra. Nanoscale 2015, 7, 11135–11141.
31.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.
32.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.
33.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.
34.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.
35.Chiu, M.-S.; Lin, C.-C.; Lee, A.-T.; Huang, Y.-C.; Huang, M. H. Aqueous-phase synthesis of size-tunable PbSe nanocubes at room temperature for optical property characterization. Chem. Eur. J. 2019, 25, 367–372.
36.Huang, M. H. Facet-dependent optical properties of semiconductor nanocrystals. Small 2019, 15, 1804726.
37.Li, J.; Zalloum, O.; Roschuk, T.; Heng, C.; Wojcik, J.; Mascher, P. The formation of light emitting cerium silicates in cerium-doped silicon oxides. Appl. Phys. Lett. 2009, 94, 011112.
38.Tian, N.; Huang, H.; Liu, C.; Dong, F.; Zhang, T.; Du, X.; Yu, S.; Zhang, Y. In situ co-pyrolysis fabrication of CeO2/g-C3N4 n–n type heterojunction for synchronously promoting photo-induced oxidation and reduction properties. J. Mater. Chem. A 2015, 3, 17120–17129.
39.崔曉莉，〈半導體電極的平帶電位〉，《化學通報》第80卷第12期，頁1160-1175，2017。
40.Zeng, C.; Hu, Y.; Huang, H. BiOBr0.75I0.25/BiOIO3 as a novel heterojunctional photocatalyst with superior visible-light-driven photocatalytic activity in removing diverse industrial pollutants. ACS Sustainable Chem. Eng. 2017, 5, 3897−3905.
41.Majeed Khan, M. A.; Khan, W.; Ahamed, M.; Alhazaa, A. N. Microstructural properties and enhanced photocatalytic performance of Zn doped CeO2 nanocrystals. Sci. Rep. 2017, 7, 12560.
42.Harrison, S.; Hayne, M. Photoelectrolysis using type-II semiconductor heterojunctions. Sci. Rep. 2017, 7, 11638.