在此篇論文中，藉由調控硝酸銨、氫氧化鉀與硝酸銀的用量，以改變反應速率，進而控制形狀與尺寸，此方法的反應時間短且反應條件簡單，透過在室溫下進行沈澱反應，成功合成出尺寸可調控的立方體、八面體、菱形十二面體氧化銀奈米粒子，尺寸範圍落在79奈米至714奈米，並探討光學和光電化學的晶面效應。這些氧化銀晶體的形狀可以在掃描式電子顯微鏡下被清楚觀察到，透過粉末式X光繞射、X射線光電子能譜分析，可以了解氧化銀晶體的成分與表面特性。在紫外可見光譜漫反射光譜圖中，可以觀察到氧化銀晶體在光學上有晶面效應和尺寸效應，能隙會隨著尺寸增加而有紅位移的現象，在相似體積但不同形狀的氧化銀晶體，能隙則是從八面體、立方體到菱形十二面體呈現藍位移的現象。在光電化學分析的實驗中，發現立方體有最大的活性表面積，菱形十二面體和截半立方體次之，八面體則是有最少的活性表面積，而在光電流的表現則是截半立方體有最大的光電流響應，立方體居中，菱形十二面體表現微弱，立方體的光電流則是最弱的。

In this study, the amounts of NH4NO3, KOH, and AgNO3 used were adjusted to control the reaction rate, which in term changed the shape and size of silver oxide nanoparticles. This approach has advantages of a short reaction time and simple reaction conditions. Size-tunable Ag2O cubes, octahedra, and rhombic dodecahedra ranging in size from 79 nm to 714 nm were effectively produced via a precipitation procedure at room temperature. Their optical and photoelectrochemical properties were investigated. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses were used to understand the composition and surface properties of the silver oxide crystals. From UV-visible diffuse reflectance spectra (DRS), crystal facet and size effects were observed, showing spectral red-shift as particle size increases. Among silver oxide nanocrystals with similar volume but different shapes, the band gap is blue-shifted from octahedra to cubes and rhombic dodecahedra. In the photoelectrochemical analysis, it was found that cubes have the most active surface area, followed by rhombic dodecahedra and cuboctahedra, while octahedra have the least active surface area. In terms of photocurrent performance, cuboctahedra show the highest photocurrent response, octahedra are second highest, and rhombic dodecahedra have a poor response. Cubes actually have the weakest photocurrent response.

摘要 i
Abstract ii
致謝 iii
Table of Contents iv
List of Figures vi
List of Tables x
List of Schemes xi
Chapter 1 Introduction 1
1.1 Facet-Dependent Effects of Semiconductors 1
1.1.1 Facet-Dependent Electrical Conductivity Properties 1
1.1.2 Facet-Dependent Photocatalytic Activity 4
1.1.3 Facet- and Size-Dependent Optical Properties 6
1.2 Property of Silver Oxide 9
1.3 Synthesis of Ag2O 10
1.4 Photoelectrochemical Water Splitting 14
1.5 Motivation 16
Chapter 2 Small Ag2O Crystal Growth and Lattice Variation Investigation 18
2.1 Experimental Section 18
2.1.1 Chemicals 18
2.1.2 Instrumentation 18
2.1.3 Synthesis of Size-Tunable Ag2O Cubes 19
2.1.4 Synthesis of Size-Tunable Ag2O Octahedra 20
2.1.5 Synthesis of Size-Tunable Ag2O Rhombic Dodecahedra 21
2.1.6 Synthesis of Ag2O Cuboctahedra 22
2.1.7 Crystal Structure Identification by Rietveld Refinement 23
2.1.8 Preparation of Ag2O/ITO Electrodes 24
2.1.9 Electrochemical and Photoelectrochemical Measurements 25
2.2 Results and Discussion 26
2.2.1 Morphology of Ag2O Nanocrystals 30
2.2.2 Crystal Structure Characterization 36
2.2.2.1 PXRD 36
2.2.2.2 HR-XRD Determination of Bulk and Surface Layer Lattices 43
2.2.2.3 Surface Layer Verification and Temperature-Dependent Lattice Variation 46
2.2.2.4 TEM 49
2.2.2.5 XPS 51
2.2.3 Size- and Facet-Dependent Optical Properties 52
2.2.4 Electrochemical Analysis of Ag2O 58
Conclusion 62
Reference 63

(1) 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 (3), 2155-2160.
(2) 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 (24), 13027-13033.
(3) Chu, C.-Y.; Huang, M. H. Facet-dependent photocatalytic properties of Cu2O crystals probed by using electron, hole and radical scavengers. J. Mater. Chem. A 2017, 5 (29), 15116-15123.
(4) 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 (3), 293-297.
(5) 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 (30), 19672-19679.
(6) Peng, Y.-W.; Wang, C.-P.; Kumar, G.; Hsieh, P.-L.; Hsieh, C.-M.; Huang, M. H. Formation of CsPbCl3 Cubes and Edge-Truncated Cuboids at Room Temperature. ACS Sustain. Chem. Eng. 2022, 10 (4), 1578-1584.
(7) Chen, J.-W.; Pal, A.; Chen, B.-H.; Kumar, G.; Chatterjee, S.; Peringeth, K.; Lin, Z.-H.; Huang, M. H. Shape-Tunable BaTiO3 Crystals Presenting Facet-Dependent Optical and Piezoelectric Properties. Small 2023, 19 (9), 2205920.
(8) Tan, C.-S.; Huang, M. H. Surface-dependent band structure variations and bond-level deviations in Cu2O. Inorg. Chem. Front. 2021, 8 (18), 4200-4208.
(9) Hsiao, C.-H.; Chen, C.-W.; Chen, H.-S.; Hsieh, P.-L.; Chen, Y.-A.; Huang, M. H. Formation of size-tunable CdS rhombic dodecahedra. J. Mater. Chem. C 2021, 9 (18), 5992-5997.
(10) Yang, Y.-C.; Peng, Y.-W.; Lee, A.-T.; Kumar, G.; Huang, M. H. CsPbBr3 and CsPbI3 rhombic dodecahedra and nanocubes displaying facet-dependent optical properties. Inorg. Chem. Front. 2021, 8 (21), 4685-4695.
(11) Madasu, M.; Hsieh, P.-L.; Chen, Y.-J.; Huang, M. H. Formation of Silver Rhombic Dodecahedra, Octahedra, and Cubes through Pseudomorphic Conversion of Ag2O Crystals with Nitroarene Reduction Activity. ACS Appl. Mater. Interfaces 2019, 11 (41), 38039-38045.
(12) Ida, Y.; Watase, S.; Shinagawa, T.; Watanabe, M.; Chigane, M.; Inaba, M.; Tasaka, A.; Izaki, M. Direct Electrodeposition of 1.46 eV Bandgap Silver(I) Oxide Semiconductor Films by Electrogenerated Acid. Chem. Mater. 2008, 20 (4), 1254-1256.
(13) Saroja, G.; Vasu, V.; Nagarani, N. Optical Studies of Ag2O Thin Film Prepared by Electron Beam Evaporation Method. Open J. Met. 2013, 03 (04), 57-63.
(14) Shume, W. M.; Murthy, H. C. A.; Zereffa, E. A. A Review on Synthesis and Characterization of Ag2O Nanoparticles for Photocatalytic Applications. J. Chem. 2020, 2020, 1-15.
(15) Wang, X.; Li, S.; Yu, H.; Yu, J.; Liu, S. Ag2O as a new visible-light photocatalyst: self-stability and high photocatalytic activity. Chem. Eur. J. 2011, 17 (28), 7777-7780.
(16) Yu, H.; Liu, R.; Wang, X.; Wang, P.; Yu, J. Enhanced visible-light photocatalytic activity of Bi2WO6 nanoparticles by Ag2O cocatalyst. Appl. Catal. B: Environ. 2012, 111-112, 326-333.
(17) Assal, M. E.; Shaik, M. R.; Kuniyil, M.; Khan, M.; Al-Warthan, A.; Alharthi, A. I.; Varala, R.; Siddiqui, M. R. H.; Adil, S. F. Ag2O nanoparticles/MnCO3, –MnO2 or –Mn2O3/highly reduced graphene oxide composites as an efficient and recyclable oxidation catalyst. Arab. J. Chem. 2019, 12 (1), 54-68.
(18) Kumar, R.; Shin, J.; Yin, L.; You, J. M.; Meng, Y. S.; Wang, J. All‐Printed, Stretchable Zn‐Ag2O Rechargeable Battery via Hyperelastic Binder for Self‐Powering Wearable Electronics. Adv. Energy Mater. 2016, 7 (8).
(19) Fakhri, A.; Tahami, S.; Nejad, P. A. Preparation and characterization of Fe3O4-Ag2O quantum dots decorated cellulose nanofibers as a carrier of anticancer drugs for skin cancer. J. Photochem. Photobiol. B: Biol. 2017, 175, 83-88.
(20) Iqbal, S.; Fakhar-e-Alam, M.; Akbar, F.; Shafiq, M.; Atif, M.; Amin, N.; Ismail, M.; Hanif, A.; Farooq, W. A. Application of silver oxide nanoparticles for the treatment of cancer. J. Mol. Struct. 2019, 1189, 203-209.
(21) Pham, Q.-T.; Huy, B. T.; Lee, Y.-I. New highly efficient electrochemical synthesis of dispersed Ag2O particles in the vicinity of the cathode with controllable size and shape. J. Mater. Chem. C 2015, 3 (29), 7720-7726.
(22) Fang, J.; Leufke, P. M.; Kruk, R.; Wang, D.; Scherer, T.; Hahn, H. External electric field driven 3D ordering architecture of silver (I) oxide meso-superstructures. Nano Today 2010, 5 (3), 175-182.
(23) Murray, B. J.; Li, Q.; Newberg, J. T.; Menke, E. J.; Hemminger, J. C.; Penner, R. M. Shape- and size-selective electrochemical synthesis of dispersed silver(I) oxide colloids. Nano Lett. 2005, 5 (11), 2319-2324.
(24) Yan, Z.; Bao, R.; Chrisey, D. B. Generation of Ag2O micro-/nanostructures by pulsed excimer laser ablation of Ag in aqueous solutions of polysorbate 80. Langmuir 2011, 27 (2), 851-855.
(25) Wang, X.; Wu, H. F.; Kuang, Q.; Huang, R. B.; Xie, Z. X.; Zheng, L. S. Shape-dependent antibacterial activities of Ag2O polyhedral particles. Langmuir 2010, 26 (4), 2774-2778.
(26) 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 (47), 14167-14174.
(27) Wang, G.; Ma, X.; Huang, B.; Cheng, H.; Wang, Z.; Zhan, J.; Qin, X.; Zhang, X.; Dai, Y. Controlled synthesis of Ag2O microcrystals with facet-dependent photocatalytic activities. J. Mater. Chem. 2012, 22 (39).
(28) Franz, S.; Arab, H.; Chiarello, G. L.; Bestetti, M.; Selli, E. Single‐Step Preparation of Large Area TiO2 Photoelectrodes for Water Splitting. Adv. Energy Mater. 2020, 10 (23).
(29) Kim, J. H.; Lee, J. S. Elaborately Modified BiVO4 Photoanodes for Solar Water Splitting. Adv. Mater. 2019, 31 (20), 1806938.
(30) Pan, L.; Liu, Y.; Yao, L.; Dan, R.; Sivula, K.; Gratzel, M.; Hagfeldt, A. Cu2O photocathodes with band-tail states assisted hole transport for standalone solar water splitting. Nat. Commun. 2020, 11 (1), 318.
(31) Zhang, J.; Xu, Q.; Wang, J.; Li, Y.; Jiang, H.; Li, C. Dual-defective Co3O4 nanoarrays enrich target intermediates and promise high-efficient overall water splitting. Chem. Eng. J. 2021, 424.
(32) Hao, C.; Wang, W.; Zhang, R.; Zou, B.; Shi, H. Enhanced photoelectrochemical water splitting with TiO2@Ag2O nanowire arrays via p-n heterojunction formation. Sol. Energy Mater. Sol. 2018, 174, 132-139.
(33) Ma, H.-H.; Huang, M. H. Size- and facet-dependent photoelectrochemical properties of Cu2O crystals. J. Mater. Chem. C 2023, 11 (17), 5857-5866.
(34) Kim, D.; Jeong, S.; Moon, J. Synthesis of silver nanoparticles using the polyol process and the influence of precursor injection. Nanotechnology 2006, 17 (16), 4019-4024.
(35) Young, R. A. The Rietveld Methods; Oxford University Press Inc., 1993.
(36) Attfield, J. P. Mechanisms and Materials for NTE. Front. Chem. 2018, 6, 371.
(37) Dove, M. T.; Fang, H. Negative Thermal Expansion and Associated Anomalous Physical Properties: Review of The Lattice Dynamics Theoretical Foundation. Rep. Prog. Phys. 2016, 79 (6), 066503.
(38) Sanson, A. On The Switching Between Negative and Positive Thermal Expansion in Framework Materials. Mater. Res. Lett. 2019, 7 (10), 412-417.
(39) Miller, W.; Smith, C. W.; Mackenzie, D. S.; Evans, K. E. Negative Thermal Expansion: A Review. J. Mater. Sci. 2009, 44 (20), 5441-5451.
(40) Yang, Z.-H.; Ho, C.-H.; Lee, S. Plasma-induced formation of flower-like Ag2O nanostructures. Appl. Surf. Sci. 2015, 349, 609-614.
(41) Harn, Y.-W.; Yang, T.-H.; Tang, T.-Y.; Chen, M.-C.; Wu, J.-M. Facet-Dependent Photocatalytic Activity and Facet-Selective Etching of Silver(I) Oxide Crystals with Controlled Morphology. ChemCatChem 2015, 7 (1), 80-86.