此研究顯示氧化亞銅多面體的光催化活性可藉由修飾4-乙炔基苯甲腈、4-氟苯乙炔、4-氯苯乙炔、4-溴苯乙炔來增進。具光催化惰性的氧化亞銅正立方體被這些分子激活，菱形十二面體和正八面體氧化亞銅的光催化活性在修飾了4-乙炔基苯甲腈後也有提升。紅外光譜確認分子和氧化亞銅的鍵結。實驗發現電洞在甲基橙降解反應中比電子起著更重要的作用，並揭示了電子在修飾了4-氟苯乙炔、4-氯苯乙炔、4-溴苯乙炔的氧化亞銅中不同程度的重要性。電子自旋共振光譜儀的測量表明羥基自由基在水溶液中是主要的活性物質。X射線光電子能譜儀揭示分子修飾後氧化亞銅的電子密度會有變化。修飾4-乙炔基苯甲腈的氧化亞銅立方體可進行光催化之芳基硼酸羥基化反應。從密度泛函理論計算中揭示接4-乙炔基苯甲腈後所會產生能隙態以促進電子轉移到分子，另外電荷密度差的積分值和Bader電荷差計算也支持這個結果。4-乙炔基苯甲腈與真空能級之間的位能差變小也有助於電子可以經由4-乙炔基苯甲腈出去。

Photocatalytic activities of Cu2O polyhedra are enhanced by modifying with various molecules such as 4-cyanophenylacetylene (4-CNA), 4-fluorophenylacetylene (4-FA), 4-chlorophenylacetylene (4-CA), and 4-bromophenylacetylene (4-BA). The photocatalytically inert Cu2O cubes are activated by all these molecules, while those of Cu2O rhombic dodecahedra and octahedra were also enhanced with 4-CNA functionalization. Infrared spectroscopy was used to confirm the bonding of molecules to Cu2O crystals. Hole and electron scavenger examinations showed that holes play a more important role than electrons in methyl orange degradation reaction, and revealed different degrees of importance of electrons in 4-FA, 4-CA, and 4-BA cases. EPR measurements indicated that hydroxyl radical is the major reactive species in aqueous solution. XPS technique revealed the electron density changes of Cu2O after modifying molecules. 4-CNA-modified Cu2O cubes can also photocatalyze arylboronic acid hydroxylation reactions. Density functional theory (DFT) calculations were conducted for 4-CNA-modified Cu2O surfaces, revealing the emergence of a 4-CNA-induced in-gap state to facilitate electron transfer to the molecule. Charge density difference and Bader charge difference calculations also support this result. The potential difference between 4-CNA and the vacuum level become smaller implying that electrons can escape from Cu2O through 4-CNA.

1. Chen, K. F.; Sun, C. T.; Song, S. Y.; Xue, D. F. Polymorphic Crystallization of Cu2O Compound. Crystengcomm 2014, 16 (24), 5257-5267.
2. Zhang, Y.; Deng, B.; Zhang, T. R.; Gao, D. M.; Xu, A. W. Shape Effects of Cu2O Polyhedral Microcrystals on Photocatalytic Activity. J. Phys. Chem. C 2010, 114 (11), 5073-5079.
3. Zhang, J. T.; Liu, J. F.; Peng, Q.; Wang, X.; Li, Y. D. Nearly Monodisperse Cu2O and CuO Nanospheres: Preparation and Applications for Sensitive Gas Sensors. Chem. Mat. 2006, 18 (4), 867-871.
4. Liu, Y. J.; Zhu, J. D.; Cai, L.; Yao, Z. R.; Duan, C. Y.; Zhao, Z. J.; Zhao, C. X.; Mai, W. J. Solution-Processed High-Quality Cu2O Thin Films as Hole Transport Layers for Pushing the Conversion Efficiency Limit of Cu2O/Si Heterojunction Solar Cells. Sol PRL 2020, 4 (1), 1900339.
5. Zhang, S. S.; Yan, J.; Yang, S. Y.; Xu, Y. H.; Cai, X.; Li, X.; Zhang, X. C.; Peng, F.; Fang, Y. P. Electrodeposition of Cu2O/g-C3N4 Heterojunction Film on an FTO Substrate for Enhancing Visible Light Photoelectrochemical Water Splitting. Chin. J. Catal. 2017, 38 (2), 365-371.
6. Huang, M. H.; Madasu, M. Facet-Dependent and Interfacial Plane-Related Photocatalytic Behaviors of Semiconductor Nanocrystals and Heterostructures. Nano Today 2019, 28, 100768.
7. 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 (1), 4-15.
8. Huang, M. H. Facet-Dependent Optical Properties of Semiconductor Nanocrystals. Small 2019, 15 (7), 1804726.
9. Kim, C. W.; Yeob, S. J.; Cheng, H.-M.; Kang, Y. S. A Selectively Exposed Crystal Facet-Engineered TiO2 Thin Film Photoanode for the Higher Performance of the Photoelectrochemical Water Splitting Reaction. Energy Environ. Sci. 2015, 8 (12), 3646-3653.
10. Wang, Y. L.; Li, Y. H.; Wang, X. L.; Hou, Y.; Chen, A. P.; Yang, H. G. Effects of Redox Mediators on α-Fe2O3 Exposed by {012} and {104} Facets for Photocatalytic Water Oxidation. Appl. Catal. B 2017, 206, 216-220.
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 (22), 13664-13671.
12. 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.
13. 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.
14. 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.
15. Wang, C. H.; Shao, C. L.; Zhang, X. T.; Liu, Y. C. SnO2 Nanostructures-TiO2 Nanofibers Heterostructures: Controlled Fabrication and High Photocatalytic Properties. Inorg. Chem. 2009, 48 (15), 7261-7268.
16. Guo, Z. Y.; Huo, W. C.; Cao, T.; Liu, X. Y.; Ren, S.; Yang, J.; Ding, H.; Chen, K.; Dong, F.; Zhang, Y. X. Heterojunction Interface of Zinc Oxide and Zinc Sulfide Promoting Reactive Molecules Activation and Carrier Separation Toward Efficient Photocatalysis. J. Colloid Interface Sci. 2021, 588, 826-837.
17. Wang, S. B.; Wang, Y.; Zang, S. Q.; Lou, X. W. Hierarchical Hollow Heterostructures for Photocatalytic CO2 Reduction and Water Splitting. Small Methods 2020, 4 (1), 1900586.
18. Dutta, S. K.; Mehetor, S. K.; Pradhan, N. Metal Semiconductor Heterostructures for Photocatalytic Conversion of Light Energy. J Phys. Chem. Lett. 2015, 6 (6), 936-944.
19. Wu, S.-C.; Tan, C.-S.; Huang, M. H. Strong Facet Effects on Interfacial Charge Transfer Revealed through the Examination of Photocatalytic Activities of Various Cu2O-ZnO Heterostructures. Adv. Funct. Mater. 2017, 27 (9), 1604635.
20. Naresh, G.; Hsieh, P.-L.; Meena, V.; Lee, S.-K.; Chiu, Y.-H.; Madasu, M.; Lee, A.-T.; Tsai, H.-Y.; Lai, T.-H.; Hsu, Y.-J.; Lo, Y.-C.; Huang, M. H. Facet-Dependent Photocatalytic Behaviors of ZnS-Decorated Cu2O Polyhedra Arising from Tunable Interfacial Band Alignment. ACS Appl. Mater. Interfaces 2019, 11 (3), 3582-3589.
21. Huang, J.-Y.; Hsieh, P.-L.; Naresh, G.; Tsai, H.-Y.; Huang, M. H. Photocatalytic Activity Suppression of CdS Nanoparticle-Decorated Cu2O Octahedra and Rhombic Dodecahedra. J. Phys. Chem. C 2018, 122 (24), 12944-12950.
22. Naresh, G.; Lee, A.-T.; Meena, V.; Satyanarayana, M.; Huang, M. H. Photocatalytic Activity Suppression of Ag3PO4-Deposited Cu2O Octahedra and Rhombic Dodecahedra. J. Phys. Chem. C 2019, 123 (4), 2314-2320.
23. Liang, T.-Y.; Chan, S.-J.; Patra, A.-S.; Hsieh, P.-L.; Chen, Y.-A.; Ma, H.-H.; Huang, M. H. Inactive Cu2O Cubes Become Highly Photocatalytically Active with Ag2S Deposition. ACS Appl. Mater. Interfaces 2021, 13 (9), 11515-11523.
24. Sodeyama, K.; Sumita, M.; O'Rourke, C.; Terranova, U.; Isam, A.; Han, L. Y.; Bowler, D. R.; Tateyama, Y. Protonated Carboxyl Anchor for Stable Adsorption of Ru N749 Dye (Black Dye) on a TiO2 Anatase (101) Surface. J. Phys. Chem. Lett. 2012, 3 (4), 472-477.
25. Ashford, D. L.; Song, W. J.; Concepcion, J. J.; Glasson, C. R. K.; Brennaman, M. K.; Norris, M. R.; Fang, Z.; Templeton, J. L.; Meyer, T. J. Photoinduced Electron Transfer in a Chromophore-Catalyst Assembly Anchored to TiO2. J. Am. Chem. Soc. 2012, 134 (46), 19189-19198.
26. Ye, S.; Kathiravan, A.; Hayashi, H.; Tong, Y. J.; Infahsaeng, Y.; Chabera, P.; Pascher, T.; Yartsev, A. P.; Isoda, S.; Imahori, H.; Sundström, V. Role of Adsorption Structures of Zn-Porphyrin on TiO2 in Dye-Sensitized Solar Cells Studied by Sum Frequency Generation Vibrational Spectroscopy and Ultrafast Spectroscopy. J. Phys. Chem. C 2013, 117 (12), 6066-6080.
27. Peng, Y.; Lu, B. Z.; Wu, F.; Zhang, F. Q.; Lu, J. E.; Kang, X. W.; Ping, Y.; Chen, S. W. Point of Anchor: Impacts on Interfacial Charge Transfer of Metal Oxide Nanoparticles. J. Am. Chem. Soc. 2018, 140 (45), 15290-15299.
28. Chen, T.-N.; Kao, J.-C.; Zhong, X.-Y.; Chan, S.-J.; Patra, A. S.; Lo, Y.-C.; Huang, M. H. Facet-Specific Photocatalytic Activity Enhancement of Cu2O Polyhedra Functionalized with 4-Ethynylanaline Resulting from Band Structure Tuning. ACS Cent. Sci. 2020, 6 (6), 984-994.
29. Patra, A. S.; Kao, J.-C.; Chan, S.-J.; Chou, P.-J.; Chou, J.-P.; Lo, Y.-C.; Huang, M. H. Photocatalytic Activity Enhancement of Cu2O Cubes Functionalized with 2-Ethynyl-6-Methoxynaphthalene through Band Structure Modulation. J. Mater. Chem. C 2022, 10 (10), 3980-3989.
30. Chan, S.-J.; Kao, J.-C.; Chou, P.-J.; Lo, Y.-C.; Chou, J.-P.; Huang, M. H. 4-Nitrophenylacetylene-Modified Cu2O Cubes and Rhombic Dodecahedra Showing Superior Photocatalytic Activity through Surface Band Structure Modulation. J. Mater. Chem. C 2022, 10 (21), 8422-8431.
31. 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 (2), 1261-1267.
32. Ho, J.-Y.; Huang, M. H. Synthesis of Submicrometer-Sized Cu2O Crystals with Morphological Evolution from Cubic to Hexapod Structures and Their Comparative Photocatalytic Activity. J. Phys. Chem. C 2009, 113 (32), 14159-14164.
33. Chanda, K.; Rej, S.; Huang, M. H. Facet-Dependent Catalytic Activity of Cu2O Nanocrystals in the One-Pot Synthesis of 1,2,3-Triazoles by Multicomponent Click Reactions. Chem.-Eur. J. 2013, 19 (47), 16036-16043.
34. Kresse, G.; Furthmuller, J. Efficiency of ab-Initio Total Energy Calculations for Metals and Semiconductors Using a Plane-Wave Basis Set. Comp. Mater. Sci. 1996, 6 (1), 15-50.
35. Kresse, G.; Furthmuller, J. Efficient Iterative Schemes for ab Initio Total-Energy Calculations Using a Plane-Wave Basis Set. Phys. Rev. B 1996, 54 (16), 11169-11186.
36. Kresse, G.; Joubert, D. From Ultrasoft Pseudopotentials to the Projector Augmented-Wave Method. Phys. Rev. B 1999, 59 (3), 1758-1775.
37. Blochl, P. E.; Jepsen, O.; Andersen, O. K. Improved Tetrahedron Method for Brillouin-Zone Integrations. Phys. Rev. B Condens. Mat. 1994, 49 (23), 16223-16233.
38. Tang, W.; Sanville, E.; Henkelman, G. A Grid-Based Bader Analysis Algorithm Without Lattice Bias. J. Phys. Condens. Mat. 2009, 21 (8), 084204.
39. Sanville, E.; Kenny, S. D.; Smith, R.; Henkelman, G. Improved Grid-Based Algorithm for Bader Charge Allocation. J. Comput. Chem. 2007, 28 (5), 899-908.
40. Weaver, J. B.; Kozuch, J.; Kirsh, J. M.; Boxer, S. G. Nitrile Infrared Intensities Characterize Electric Fields and Hydrogen Bonding in Protic, Aprotic, and Protein Environments. J. Am. Chem. Soc. 2022, 144 (17), 7562-7567.
41. Margoshes, M.; Fassel, V. A. The Infrared Spectra of Aromatic compounds: I. The out-of-Plane C-H Bending Vibrations in the Region 625-900 cm-1. Spectrochim Acta 1955, 7 (1), 14-24.
42. Wang, J. C.; Lou, H. H.; Xu, Z. H.; Cui, C. X.; Li, Z. J.; Jiang, K.; Zhang, Y. P.; Qu, L. B.; Shi, W. N. Natural Sunlight Driven Highly Efficient Photocatalysis for Simultaneous Degradation of Rhodamine B and Methyl Orange Using I/C Codoped TiO2 Photocatalyst. J. Hazard. Mater. 2018, 360, 356-363.
43. Togashi, H.; Shinzawa, H.; Matsuo, T.; Takeda, Y.; Takahashi, T.; Aoyama, M.; Oikawa, K.; Kamada, H. Analysis of Hepatic Oxidative Stress Status by Electron Spin Resonance Spectroscopy and Imaging. Free Radical Bio. Med. 2000, 28 (6), 846-853.
44. Tahir, D.; Tougaard, S. Electronic and Optical Properties of Cu, CuO and Cu2O Studied by Electron Spectroscopy. J. Phys-Condens. Mat. 2012, 24 (17), 175002.
45. Swadzba-Kwasny, M.; Chancelier, L.; Ng, S.; Manyar, H. G.; Hardacre, C.; Nockemann, P. Facile in Situ Synthesis of Nanofluids Based on Ionic Liquids and Copper Oxide Clusters and Nanoparticles. Dalton Trans. 2012, 41 (1), 219-227.
46. Su, Z.-H.; Hsieh, M.-H.; Chen, Z.-L.; Dai, W.-T.; Wu, E.-T.; Huang, M. H. Aqueous Phase Photocatalytic Hydroxylation of Arylboronic Acids Using Polyhedral Cu2O Crystals. Chem. Mater. 2023, 35 (7), 2782-2789.
47. Osipov, V. Y.; Romanov, N. M.; Kogane, K.; Touhara, H.; Hattori, Y.; Takai, K. Intrinsic Infrared Absorption for Carbon-Fluorine Bonding in Fluorinated Nanodiamond. Mendeleev Commun. 2020, 30 (1), 84-87.