透過微波水熱法輔助成功地合成了Dion-Jacobson（DJ）相的二維（2D）鈣鈦礦結構n = 4、5和6的不同分子層的Ca2Nan-3NbnO3n+1（CNNO-）奈米片。在這裡，我們研究合成的CNNO納米片的結構，光學，化學和電學性質，以及它們在光電化學（PEC）水分解應用中之析氫反應（HER）性能。
微波輻射用於在酸交換和剝落過程中組裝鈣鈦礦層的拓撲修飾中，能夠將反應時間從數天縮短至數小時。水熱法獲得高結晶性超薄單層CNNO奈米片分子層n = 4、5和6，其厚度分別為2.561、2.955和3.328 nm。另外，剝落過程可以快速產生分散二維奈米片，並且替換中的溫度和時間參數在奈米片的光學性質中起重要作用。增加剝落溫度將減小合成的CNNO奈米片的間接帶隙，而增加剝落時間增加CNNO奈米片間接能帶能隙。
微波水熱法合成CNNO奈米片結構上表現出扭曲NbO6八面體氧空位，隨著分子層的增加形成更高比例的Nb4 +氧化態。由氧空位引起的缺陷導致局部載流子密度增加，這使得具有最高Nb4+/Nb5+比的CNNO- n=6在奈米片之間具有最高載流子濃度。氧空位缺陷亦可通過俘獲電子或電洞進行轉移載流電荷，這有助於提高由微波水熱法合成合成的CNNO奈米片之總體太陽能轉化為氫（STH）之效率，從而獲得隨n層增加而增加的PEC水分解性能。此外，使用鈷（Co）單原子之SAC-CNNO- 亦顯示了以微波水熱法合成的CNNO奈米片之PEC性能得到了極大的提高。因此，我們這項工作提出了以微波水熱法方法提升時間效率以及微波水熱法合成CNNO納米片在產氫方面潛力。

Two-dimensional (2D) layer perovskite derived from the Dion-Jacobson (DJ) phase, Ca2Nan-3NbnO3n+1- (CNNO-) nanosheets with different molecular layers of n = 4, 5, and 6, have been successfully synthesized using a microwave-assisted (MA) hydrothermal approach. Here, we investigate the structural, optical, chemical, and electrical properties of the MA-synthesized CNNO- nanosheets as well as their hydrogen evolution reaction (HER) performance in photoelectrochemical (PEC) water-splitting application.
Microwave-irradiation, which is used to assemble a topological modification of layers perovskite in the acid exchange and exfoliation processes, was able to shorten the reaction time from days to only hours. The MA-hydrothermal approach obtains a high crystalline ultrathin unilamellar CNNO- nanosheets with a thickness of 2.561, 2.955, and 3.328 nm, respectively for molecular layers of n = 4, 5, and 6. Furthermore, the MA-exfoliation process allows rapid production of dispersed 2D nanosheets, while the temperature and time parameters in the MA-exfoliation play an important role in the optical properties of the nanosheets. Increasing the MA-exfoliation temperature will decrease the indirect band gap of the MA-synthesized CNNO- nanosheets, while increasing the MA-exfoliation time allows the expansion of the indirect band gap of the MA-synthesized CNNO- nanosheets.
The MA-synthesized CNNO- nanosheets are shown to exhibit oxygen vacancies from the distorted NbO6 octahedral, forming a higher ratio of Nb4+ oxidation state as the increase of molecular layers. The defects caused by the oxygen vacancies contribute to the increase of the local carrier density, which allows the CNNO- 6 with the highest Nb4+/Nb5+ ratio to have the highest carrier concentration between the other nanosheets. The oxygen vacancy defects also allow the charge carriers transfer by trapping the electrons or holes which contribute to increasing the overall solar-to-hydrogen (STH) efficiency of the MA-synthesized CNNO- nanosheets, obtaining an increased PEC water-splitting performance with the increasing n layers. Furthermore, the development of SACs using cobalt (Co) single-atom shows massive enhancement in PEC performance of the MA-synthesized CNNO- nanosheets. Thus, our findings from this work present the time efficiency of the MA-hydrothermal approach and the potential of MA-synthesized CNNO- nanosheets for hydrogen generation. This works may also provide an insight in developing the SACs using the CNNO- nanosheets support for hydrogen generation devices.

1. Understanding the Global Energy Crisis, ed. E.D. Coyle and R.A. Simmons. 2014: Purdue University Press.
2. Liang, J., et al., A Low-Cost and High-Efficiency Integrated Device toward Solar-Driven Water Splitting. ACS Nano, 2020. 14(5): p. 5426-5434.
3. Wei, X., et al., Hybridized Mechanical and Solar Energy-Driven Self-Powered Hydrogen Production. Nano-Micro Letters, 2020. 12(1).
4. Zeng, Q.Y., et al., Efficient solar hydrogen production coupled with organics degradation by a hybrid tandem photocatalytic fuel cell using a silicon-doped TiO2 nanorod array with enhanced electronic properties. Journal of Hazardous Materials, 2020. 394.
5. Razi, F. and I. Dincer, A critical evaluation of potential routes of solar hydrogen production for sustainable development. Journal of Cleaner Production, 2020. 264.
6. Thakur, A., et al., Current progress and challenges in photoelectrode materials for the production of hydrogen. Chemical Engineering Journal, 2020. 397.
7. Lichtenberg, F., A. Herrnberger, and K. Wiedenmann, Synthesis, structural, magnetic and transport properties of layered perovskite-related titanates, niobates and tantalates of the type A(n)B(n)O(3n+2), A ' A(k-1)B(k)O(3k+1) and A(m)B(m-1)O(3m). Progress in Solid State Chemistry, 2008. 36(4): p. 253-387.
8. Wang, Y., et al., Reversible electron storage in tandem photoelectrochemical cell for light driven unassisted overall water splitting. Applied Catalysis B: Environmental, 2020. 275.
9. Zeng, Q., et al., Efficient solar hydrogen production coupled with organics degradation by a hybrid tandem photocatalytic fuel cell using a silicon-doped TiO2 nanorod array with enhanced electronic properties. J Hazard Mater, 2020. 394: p. 121425.
10. Li, X., et al., Water Splitting: From Electrode to Green Energy System. Nano-Micro Letters, 2020. 12(1).
11. Ros, C., T. Andreu, and J.R. Morante, Photoelectrochemical water splitting: a road from stable metal oxides to protected thin film solar cells. Journal of Materials Chemistry A, 2020. 8(21): p. 10625-10669.
12. Tiwari, J.N., et al., Recent Advancement of p‐ and d‐Block Elements, Single Atoms, and Graphene‐Based Photoelectrochemical Electrodes for Water Splitting. Advanced Energy Materials, 2020. 10(24).
13. Karuturi, S.K., et al., Over 17% Efficiency Stand‐Alone Solar Water Splitting Enabled by Perovskite‐Silicon Tandem Absorbers. Advanced Energy Materials, 2020. 10(28).
14. Bhat, S.S.M., et al., Substantially enhanced photoelectrochemical performance of TiO2 nanorods/CdS nanocrystals heterojunction photoanode decorated with MoS2 nanosheets. Applied Catalysis B: Environmental, 2019. 259.
15. Faraji, M., et al., Two-dimensional materials in semiconductor photoelectrocatalytic systems for water splitting. Energy & Environmental Science, 2019. 12(1): p. 59-95.
16. Kim, D., et al., Thickness-dependent bandgap and electrical properties of GeP nanosheets. Journal of Materials Chemistry A, 2019. 7(27): p. 16526-16532.
17. Xiang, W.C., et al., Europium-Doped CsPbI2Br for Stable and Highly Efficient Inorganic Perovskite Solar Cells. Joule, 2019. 3(1): p. 205-214.
18. Duan, J.L., et al., Lanthanide Ions Doped CsPbBr3 Halides for HTM-Free 10.14%-Efficiency Inorganic Perovskite Solar Cell with an Ultrahigh Open-Circuit Voltage of 1.594 V. Advanced Energy Materials, 2018. 8(31).
19. Yan, W.B., et al., Highly efficient and stable inverted planar solar cells from (FAI)(x)(MABr)(1-x)PbI2 perovskites. Nano Energy, 2017. 35: p. 62-70.
20. Benedek, N.A., et al., Understanding ferroelectricity in layered perovskites: new ideas and insights from theory and experiments. Dalton Transactions, 2015. 44(23): p. 10543-10558.
21. Li, P., et al., Low-Dimensional Dion-Jacobson-Phase Lead-Free Perovskites for High-Performance Photovoltaics with Improved Stability. Angew Chem Int Ed Engl, 2020. 59(17): p. 6909-6914.
22. Huang, P., et al., Toward Phase Stability: Dion–Jacobson Layered Perovskite for Solar Cells. ACS Energy Letters, 2019. 4(12): p. 2960-2974.
23. Ebina, Y., et al., Synthesis and In Situ X-ray Diffraction Characterization of Two-Dimensional Perovskite-Type Oxide Colloids with a Controlled Molecular Thickness. Chemistry of Materials, 2012. 24(21): p. 4201-4208.
24. Li, F., et al., Vertical Orientated Dion–Jacobson Quasi‐2D Perovskite Film with Improved Photovoltaic Performance and Stability. Small Methods, 2019. 4(5).
25. Li, B.W., et al., Atomic Layer Engineering of High-kappa Ferroelectricity in 2D Perovskites. Journal of the American Chemical Society, 2017. 139(31): p. 10868-10874.
26. Li, B.W., et al., Impact of perovskite layer stacking on dielectric responses in KCa2Nan-3NbnO3n+1 (n=3-6) Dion-Jacobson homologous series. Applied Physics Letters, 2010. 96(18).
27. Akbarian-Tefaghi, S., et al., Rapid Topochemical Modification of Layered Perovskites via Microwave Reactions. Inorg Chem, 2016. 55(4): p. 1604-12.
28. Akbarian-Tefaghi, S. and J.B. Wiley, Microwave-assisted routes for rapid and efficient modification of layered perovskites. Dalton Trans, 2018. 47(9): p. 2917-2924.
29. Akbarian-Tefaghi, S., et al., Rapid Exfoliation and Surface Tailoring of Perovskite Nanosheets via Microwave-Assisted Reactions. ChemNanoMat, 2017. 3(8): p. 538-550.
30. Wang, L.B., et al., Efficient Rapid Microwave-Assisted Route to Synthesize Monodispersive Pt Nanoparticles and Their Electrocatalytic Activity for Methanol Oxidation. Journal of Nanomaterials, 2014. 2014.
31. Akbarian-Tefaghi, S., et al., Rapid Topochemical Modification of Layered Perovskites via Microwave Reactions. Inorganic Chemistry, 2016. 55(4): p. 1604-1612.
32. Akbarian-Tefaghi, S. and J.B. Wiley, Microwave-assisted routes for rapid and efficient modification of layered perovskites. Dalton Transactions, 2018. 47(9): p. 2917-2924.
33. Liu, Y., et al., Ru Modulation Effects in the Synthesis of Unique Rod-like Ni@Ni2P-Ru Heterostructures and Their Remarkable Electrocatalytic Hydrogen Evolution Performance. Journal of the American Chemical Society, 2018. 140(8): p. 2731-2734.
34. Zou, X.X. and Y. Zhang, Noble metal-free hydrogen evolution catalysts for water splitting. Chemical Society Reviews, 2015. 44(15): p. 5148-5180.
35. Vij, V., et al., Nickel-Based Electrocatalysts for Energy-Related Applications: Oxygen Reduction, Oxygen Evolution, and Hydrogen Evolution Reactions. Acs Catalysis, 2017. 7(10): p. 7196-7225.
36. Sultan, S., et al., Single Atoms and Clusters Based Nanomaterials for Hydrogen Evolution, Oxygen Evolution Reactions, and Full Water Splitting. Advanced Energy Materials, 2019. 9(22).
37. Chen, Y.J., et al., Single-Atom Catalysts: Synthetic Strategies and Electrochemical Applications. Joule, 2018. 2(7): p. 1242-1264.
38. Jena, P., et al., Structural characterization and photoluminescence properties of sol-gel derived nanocrystalline BaMoO4:Dy3+. Journal of Luminescence, 2015. 158: p. 203-210.
39. Liu, M.M., et al., Atomically dispersed metal catalysts for the oxygen reduction reaction: synthesis, characterization, reaction mechanisms and electrochemical energy applications. Energy & Environmental Science, 2019. 12(10): p. 2890-2923.
40. Zhang, B., et al., Atomically Dispersed Pt1-Polyoxometalate Catalysts: How Does Metal-Support Interaction Affect Stability and Hydrogenation Activity? J Am Chem Soc, 2019. 141(20): p. 8185-8197.
41. Zhu, C., et al., Single-Atom Electrocatalysts. Angew Chem Int Ed Engl, 2017. 56(45): p. 13944-13960.
42. Flytzani-Stephanopoulos, M. and B.C. Gates, Atomically dispersed supported metal catalysts. Annu Rev Chem Biomol Eng, 2012. 3: p. 545-74.
43. Zhang, Q. and J. Guan, Single‐Atom Catalysts for Electrocatalytic Applications. Advanced Functional Materials, 2020. 30(31).
44. Yang, X.F., et al., Single-Atom Catalysts: A New Frontier: in Heterogeneous Catalysis. Acc Chem Res, 2013. 46(8): p. 1740–1748.
45. Jin, X., et al., Electron Configuration Modulation of Nickel Single Atoms for Elevated Photocatalytic Hydrogen Evolution. Angew Chem Int Ed Engl, 2020. 59(17): p. 6827-6831.
46. Li, H., et al., Cobalt single atoms anchored on N-doped ultrathin carbon nanosheets for selective transfer hydrogenation of nitroarenes. Science China Materials, 2019. 62(9): p. 1306-1314.
47. Li, W., et al., Bottom-Up Construction of Active Sites in a Cu-N-4-C Catalyst for Highly Efficient Oxygen Reduction Reaction. Acs Nano, 2019. 13(3): p. 3177-3187.
48. Mashkovtsev, M.A., et al., Structural characterization and photoluminescence of (Gd1-xErx)(2)O-3 nanophosphors synthesized by co-precipitation of layered precursors. Ceramics International, 2021. 47(2): p. 2725-2734.
49. Li, J., et al., Ultrahigh-Loading Zinc Single-Atom Catalyst for Highly Efficient Oxygen Reduction in Both Acidic and Alkaline Media. Angewandte Chemie International Edition, 2019. 58(21): p. 7035-7039.
50. Lau, T.H.M., et al., Transition metal atom doping of the basal plane of MoS2 monolayer nanosheets for electrochemical hydrogen evolution. Chemical Science, 2018. 9(21): p. 4769-4776.
51. Chen, W., et al., General synthesis of single atom electrocatalysts via a facile condensation–carbonization process. Journal of Materials Chemistry A, 2020. 8(48): p. 25959-25969.
52. Zhang, Q. and J. Guan, Atomically dispersed catalysts for hydrogen/oxygen evolution reactions and overall water splitting. Journal of Power Sources, 2020. 471.
53. Song, Z.N., et al., Pathways toward high-performance perovskite solar cells: review of recent advances in organo-metal halide perovskites for photovoltaic applications. Journal of Photonics for Energy, 2016. 6(2).
54. Watthage, S.C., et al., Chapter 3 - Evolution of Perovskite Solar Cells, in Perovskite Photovoltaics, S. Thomas and A. Thankappan, Editors. 2018, Academic Press. p. 43-88.
55. Reshmi Varma, P.C., Low-Dimensional Perovskites. 2018, Elsevier. p. 197-229.
56. Johnsson, M. and P. Lemmens, Crystallography and Chemistry of Perovskites. Handbook of Magnetism and Advanced Magnetic Materials, 2007.
57. Goff, R.J., et al., Leakage and Proton Conductivity in the Predicted Ferroelectric CsBiNb2O7. Chemistry of Materials, 2009. 21(7): p. 1296-1302.
58. Snedden, A., K.S. Knight, and P. Lightfoot, Structural distortions in the layered perovskites CsANb2O7 (A=Nd, Bi). Journal of Solid State Chemistry, 2003. 173(2): p. 309-313.
59. Jacobson, A.J., J.W. Johnson, and J.T. Lewandowski, Interlayer chemistry between thick transition-metal oxide layers: synthesis and intercalation reactions of K[Ca2Nan-3NbnO3n+1] (3 .ltoreq. n .ltoreq. 7). Inorganic Chemistry, 1985. 24(23): p. 3727-3729.
60. Dion, M., M. Ganne, and M. Tournoux, Nouvelles familles de phases MIMII2Nb3O10 a feuillets “perovskites”. Materials Research Bulletin, 1981. 16(11): p. 1429-1435.
61. Withers, R.L., J.G. Thompson, and A.D. Rae, The crystal chemistry underlying ferroelectricity in Bi4Ti3O12, Bi3TiNbO9, and Bi2WO6. Journal of Solid State Chemistry, 1991. 94(2): p. 404-417.
62. Elcombe, M.M., et al., Structure determinations for Ca3Ti2O7, Ca4Ti3O10, Ca3.6Sr0.4Ti3O10 and a refinement of Sr3Ti2O7. Acta Crystallographica Section B, 1991. 47(3): p. 305-314.
63. Ruddlesden, S.N. and P. Popper, New compounds of the K2NIF4 type. Acta Crystallographica, 1957. 10(8): p. 538-539.
64. Hervoches, C.H., J.T.S. Irvine, and P. Lightfoot, Two high-temperature paraelectric phases in Sr0.85Bi2.1Ta2O9. Physical Review B, 2001. 64(10): p. 100102.
65. Perez-Mato, J.M., et al., Competing structural instabilities in the ferroelectric Aurivillius compound SrBi2Ta2O9. Physical Review B, 2004. 70(21): p. 214111.
66. Boullay, P., et al., Phase transition sequence in ferroelectric Aurivillius compounds investigated by single crystal X-ray diffraction. Solid State Sciences, 2012. 14(9): p. 1367-1371.
67. Osada, M. and T. Sasaki, Nanoarchitectonics in dielectric/ferroelectric layered perovskites: from bulk 3D systems to 2D nanosheets. Dalton Transactions, 2018. 47(9): p. 2841-2851.
68. Gopalakrishnan, J., Chimie Douce Approaches to the Synthesis of Metastable Oxide Materials. Chemistry of Materials, 1995. 7(7): p. 1265-1275.
69. Schaak, R.E. and T.E. Mallouk, Perovskites by design: A toolbox of solid-state reactions. Chemistry of Materials, 2002. 14(4): p. 1455-1471.
70. Zhu, T., et al., Theory and Neutrons Combine To Reveal a Family of Layered Perovskites without Inversion Symmetry. Chemistry of Materials, 2017. 29(21): p. 9489-9497.
71. Benedek, N.A., Origin of Ferroelectricity in a Family of Polar Oxides: The Dion—Jacobson Phases. Inorganic Chemistry, 2014. 53(7): p. 3769-3777.
72. Fang, M., C.H. Kim, and T.E. Mallouk, Dielectric Properties of the Lamellar Niobates and Titanoniobates AM2Nb3O10 and ATiNbO5 (A = H, K, M = Ca, Pb), and Their Condensation Products Ca4Nb6O19 and Ti2Nb2O9. Chemistry of Materials, 1999. 11(6): p. 1519-1525.
73. Aziza, M.R., et al., Dion–Jacobson Phase Perovskite Ca2Nan–3NbnO3n+1– (n = 4–6) Nanosheets as High-κ Photovoltaic Electrode Materials in a Solar Water-Splitting Cell. ACS Applied Nano Materials, 2020. 3(7): p. 6367-6375.
74. Zhang, W., et al., Two-Dimensional Layered Oxide Structures Tailored by Self-Assembled Layer Stacking via Interfacial Strain. ACS Applied Materials & Interfaces, 2016. 8(26): p. 16845-16851.
75. Wu, C., et al., Alternative Type Two-Dimensional–Three-Dimensional Lead Halide Perovskite with Inorganic Sodium Ions as a Spacer for High-Performance Light-Emitting Diodes. ACS Nano, 2019. 13(2): p. 1645-1654.
76. Loupy, A. and J.L. Luche, Sonochemical and microwave activation in phase transfer catalysis. 1997, Springer Netherlands. p. 369-404.
77. Kappe, C.O., Controlled Microwave Heating in Modern Organic Synthesis. Angewandte Chemie International Edition, 2004. 43(46): p. 6250-6284.
78. Van der Eycken, E.V., Practical Microwave Synthesis for Organic Chemists.Strategies, Instruments, and Protocols. Edited by C. Oliver Kappe, Doris Dallinger and Shaun Murphree. Angewandte Chemie International Edition, 2009. 48(16): p. 2828-2829.
79. Baghbanzadeh, M., et al., Microwave-Assisted Synthesis of Colloidal Inorganic Nanocrystals. Angewandte Chemie International Edition, 2011. 50(48): p. 11312-11359.
80. Bogdal, D., Chapter 2 - Microwave effect vs. thermal effect, in Tetrahedron Organic Chemistry Series, D. Bogdal, Editor. 2005, Elsevier. p. 13-21.
81. Suzuki, H., et al., Reactions of Alkoxyl Derivatives of a Layered Perovskite with Alcohols:  Substitution Reactions on the Interlayer Surface of a Layered Perovskite. Chemistry of Materials, 2003. 15(3): p. 636-641.
82. Tahara, S. and Y. Sugahara, Interlayer Surface Modification of the Protonated Triple-Layered Perovskite HCa2Nb3O10•xH2O with n-Alcohols. Langmuir, 2003. 19(22): p. 9473-9478.
83. Tong, Z., et al., Preparation and Characterization of a Transparent Thin Film of the Layered Perovskite, K2La2Ti3O10, Intercalated with an Ionic Porphyrin. Chemistry Letters, 2005. 34(5): p. 632-633.
84. Gopalakrishnan, J. and V. Bhat, A2Ln2Ti3O10 (A = potassium or rubidium; Ln = lanthanum or rare earth): a new series of layered perovskites exhibiting ion exchange. Inorganic Chemistry, 1987. 26(26): p. 4299-4301.
85. Wang, Y., et al., Post-Synthesis Modification of the Aurivillius Phase Bi2SrTa2O9 via In Situ Microwave-Assisted "Click Reaction". Inorganic chemistry, 2016. 55(19): p. 9790-9797.
86. Aruchamy, A., G. Aravamudan, and G.V. Subba Rao, Semiconductor based photoelectrochemical cells for solar energy conversion—An overview. Bulletin of Materials Science, 1982. 4(5): p. 483-526.
87. Minggu, L.J., W.R. Wan Daud, and M.B. Kassim, An overview of photocells and photoreactors for photoelectrochemical water splitting. International Journal of Hydrogen Energy, 2010. 35(11): p. 5233-5244.
88. Dias, P. and A. Mendes, Hydrogen Production from Photoelectrochemical Water Splitting, in Encyclopedia of Sustainability Science and Technology, R.A. Meyers, Editor. 2017, Springer New York: New York, NY. p. 1-52.
89. Miller, E.L., Solar hydrogen production by photoelectrochemical water splitting: The promise and challenge. 2009, Wiley Online Library. p. 3-35.
90. Qiao, B., et al., Single-atom catalysis of CO oxidation using Pt1/FeOx. Nature Chemistry, 2011. 3(8): p. 634-641.
91. Liu, J., et al., Supported single-atom catalysts: synthesis, characterization, properties, and applications. Environmental Chemistry Letters, 2017. 16(2): p. 477-505.
92. Chatterjee, A.K., 8 - X-Ray Diffraction, in Handbook of Analytical Techniques in Concrete Science and Technology, V.S. Ramachandran and J.J. Beaudoin, Editors. 2001, William Andrew Publishing: Norwich. p. 275-332.
93. Welker, R.W., Size Analysis and Identification of Particles, in Developments in Surface Contamination and Cleaning, R.K. and and K.L. Mittal, Editors. 2011, William Andrew Publishing: Oxford. p. 179-213.
94. Tang, C.Y. and Z. Yang, Transmission Electron Microscopy (TEM), in Membrane Characterization, e.a. N. Hilal, Editor. 2017, Elsevier. p. 145-159.
95. Van Benthem, K. and S.J. Pennycook, Atomic Resolution Characterization of Semiconductor Materials by Aberration-Corrected Transmission Electron Microscopy, in Comprehensive Semiconductor Science and Technology, P. Bhattacharya, R. Fornari, and H. Kamimura, Editors. 2011, Elsevier: Amsterdam. p. 287-307.
96. Farré, M. and D. Barceló, Chapter 1 - Introduction to the Analysis and Risk of Nanomaterials in Environmental and Food Samples, in Comprehensive Analytical Chemistry, M. Farré and D. Barceló, Editors. 2012, Elsevier. p. 1-32.
97. Passos, M.L.C., et al., Organic Compounds, in Reference Module in Chemistry, Molecular Sciences and Chemical Engineering. 2018.
98. Bluhm, H., X-ray photoelectron spectroscopy (XPS) for in situ characterization of thin film growth, in In Situ Characterization of Thin Film Growth. 2011. p. 75-98.
99. Almora, O., et al., On Mott-Schottky analysis interpretation of capacitance measurements in organometal perovskite solar cells. Applied Physics Letters, 2016. 109(17): p. 173903.
100. Kim, E.S., et al., Crystal Structure Dependence of Electrical Properties of Li0.02(Ki1-x Nax)0.98NbO3 Ceramics. Advances in Multifunctional Materials and Systems, 2010: p. 93-103.
101. Fischer, M., et al., Structure and stability of Cd2Nb2O7 and Cd2Ta2O7 explored by ab initio calculations. Physical Review B, 2008. 78(1): p. 014108.
102. Goh, E.S.M., et al., Thickness effect on the band gap and optical properties of germanium thin films. Journal of Applied Physics, 2010. 107(2).
103. Gaponenko, S.V., Optical Properties of Semiconductor Nanocrystals. Cambridge Studies in Modern Optics. 1998, Cambridge: Cambridge University Press.
104. Shik, A.Y., Quantum wells: physics and electronics of two-dimensional systems. 1997: World Scientific.
105. Fox, M., Optical properties of solids. 2002, American Association of Physics Teachers.
106. Xu, J.P., et al., The thickness-dependent band gap and defect features of ultrathin ZrO2 films studied by spectroscopic ellipsometry. Physical Chemistry Chemical Physics, 2016. 18(4): p. 3316-3321.
107. Rajesh, N., et al., Microwave Irradiation Effect on Structural, Optical, and Thermal Properties of Cadmium Oxide Nanostructure. Acta Physica Polonica A, 2014. 125(5): p. 1229-1235.
108. Irkhin, V.Y. and M.I. Katsnelson, Temperature-Dependence of Energy-Gap and Electronic Specific-Heat in Intermediate Valence Semiconductors. Solid State Communications, 1986. 58(12): p. 881-884.
109. Wang, N., et al., High-efficiency exfoliation of layered materials into 2D nanosheets in switchable CO2/Surfactant/H2O system. Scientific Reports, 2015. 5.
110. Taran, L. and R. Rasuli, Cost-effective liquid-phase exfoliation of molybdenum disulfide by prefreezing and thermal-shock. Advanced Powder Technology, 2017. 28(11): p. 2996-3003.
111. Kreissl, H.T., et al., Structural Studies of Bulk to Nanosize Niobium Oxides with Correlation to Their Acidity. Journal of the American Chemical Society, 2017. 139(36): p. 12670-12680.
112. Zhang, W., et al., Platinum nanoparticles supported on defective tungsten bronze-type KSr2Nb5O15 as a novel photocatalyst for efficient ethylene oxidation. Journal of Materials Chemistry A, 2017. 5(36): p. 18998-19006.
113. Lima, A.R.F., et al., Structural characterization and photoluminescence behavior of pure and doped potassium strontium niobates ceramics with tetragonal tungsten-bronze structure. Ceramics International, 2016. 42(4): p. 4709-4714.
114. Kabongo, G., et al., Microwave Irradiation Induces Oxygen Vacancy in Metal Oxides based Materials and Devices: A Review. Journal of Nanosciences: Current Research, 2018. 03(02).
115. Su, X.F., et al., The preparation of oxygen-deficient ZnO nanorod arrays and their enhanced field emission. Materials Science in Semiconductor Processing, 2017. 67: p. 55-61.
116. Wang, J.P., et al., Oxygen Vacancy Induced Band-Gap Narrowing and Enhanced Visible Light Photocatalytic Activity of ZnO. Acs Applied Materials & Interfaces, 2012. 4(8): p. 4024-4030.
117. Bera, B., et al., Density of States, Carrier Concentration, and Flat Band Potential Derived from Electrochemical Impedance Measurements of N-Doped Carbon and Their Influence on Electrocatalysis of Oxygen Reduction Reaction. Journal of Physical Chemistry C, 2017. 121(38): p. 20850-20856.
118. Hankin, A., J.C. Alexander, and G.H. Kelsall, Constraints to the flat band potential of hematite photo-electrodes. Physical Chemistry Chemical Physics, 2014. 16(30): p. 16176-16186.
119. Ohtani, B., Chapter 10 - Photocatalysis by inorganic solid materials: Revisiting its definition, concepts, and experimental procedures, in Advances in Inorganic Chemistry, R.v. Eldik and G. Stochel, Editors. 2011, Academic Press. p. 395-430.
120. Böer, K.W. and U.W. Pohl, Equilibrium Statistics of Carriers, in Semiconductor Physics. 2018. p. 815-846.
121. Cui, H.L., et al., Black nanostructured Nb2O5 with improved solar absorption and enhanced photoelectrochemical water splitting. Journal of Materials Chemistry A, 2015. 3(22): p. 11830-11837.
122. Sitara, E., et al., Efficient Photoelectrochemical Water Splitting by Tailoring MoS2/CoTe Heterojunction in a Photoelectrochemical Cell. Nanomaterials, 2020. 10(12): p. 2341.
123. Wang, G.M., et al., Computational and Photoelectrochemical Study of Hydrogenated Bismuth Vanadate. Journal of Physical Chemistry C, 2013. 117(21): p. 10957-10964.
124. Chen, N., et al., A Dual-Heterojunction Cu2O/CdS/ZnO Nanotube Array Photoanode for Highly Efficient Photoelectrochemical Solar-Driven Hydrogen Production with 2.8% Efficiency. Journal of Physical Chemistry C, 2020. 124(40): p. 21968-21977.
125. Yu, J., et al., The effect of single atom substitution (O, S or Se) on photocatalytic hydrogen evolution for triazine-based conjugated porous polymers. Journal of Materials Chemistry C, 2020. 8(26): p. 8887-8895.
126. Guo, Y.Q., et al., A strategy for enhancing the photoactivity of g-C3N4-based single-atom catalysts via sulphur doping: a theoretical study. Physical Chemistry Chemical Physics, 2021. 23(11): p. 6632-6640.
127. Wu, C., et al., Molybdenum Carbide-Decorated Metallic Cobalt@Nitrogen-Doped Carbon Polyhedrons for Enhanced Electrocatalytic Hydrogen Evolution. Small, 2018. 14(16).