本研究透過將二硫化鉬生長於碳纖維(carbon fiber)表面，形成三維結構的MoS2/carbon fiber壓電過濾膜，能夠直接填充在污水管路中，透過水流的機械力直接分解有機污染物。在我們的實驗中，降解10 ppm的羅丹明Ｂ(Rhodamine B, RhB)溶液的反應速率常數(kobs)達到0.061 min-1。而且，具有高度的可重複性與穩定性，經過重複3次的降解實驗，碳纖維表面的二硫化鉬奈米花結構都沒有被破壞。這個研究解決了壓電觸媒材料在水溶液中團聚以及粉末造成水體二次污染的問題，進一步提高降解效率以及壓電觸媒降解技術實際工業化的潛力。
除了壓電催化之外，本研究亦提出了全新的污水降解技術，透過混合二硒化鉬(MoSe2)與過氧化氫(H2O2)溶液，形成極度熱力學不平衡的硒酸與亞硒酸混合氧化溶液(稱為MS oxidized solution)。這種混合溶液具有超高的氧化活性，能夠快速分解水中的有機污染分子。其具有極高的分解效率，在我們的實驗中分解10 ppm的RhB溶液的反應動力學常數達到0.53 min-1，這是傳統上二氧化鈦光觸媒降解的65倍。除此之外，這種高氧化溶液亦能夠處理超高濃度的有機污染物，在30分鐘之內能夠分解80%的1500 ppm的RhB溶液，其kobs達到0.077 min-1，這是有報導以來最高的降解濃度。本研究亦調查了降解過後的廢水能夠直接100%重複利用於農業灌溉，對植物沒有任何負面的生長影響。透過二次水熱法，能夠將從廢水中重建二硒化鉬奈米花粉末，達到零排放的目標。

The recycling of catalyst materials and the subsequent generation of secondary pollution are the main challenges in the field of catalyst degradation. In this study, MoS2 nanoflowers (NFs)/carbon fiber was synthesized to form a 3D piezocatalystic filter that can decompose wastewater easily without generating secondary pollutants in treated water. The MoS2/carbon fiber was constructed in pipelines to form the circulatory piezoelectric degradation system, which demonstrated high efficiency in decomposing organic molecules in wastewater through natural mechanical water flow. The reaction rate constant (kobs) for the degradation of 10 ppm Rhodamine B (Rhodamine B, RhB) solution reaches 0.061 min-1. Theoretical calculations indicated that the MoS2/carbon fibers exhibits a significant piezoelectric potential on both sides when mechanical force is applied. This established considerable piezoelectric potential at MoS2 NFs active edge sites and MoS2–carbon fiber interfaces, triggering electron–hole pair separation under the internal electric field. The MoS2/carbon fiber piezoelectric catalyst is advantageous for its reusability and recyclability, thus preventing secondary pollution and adverse effects on water bodies during practical high-flux wastewater treatment.
In addition to MoS2/carbon fiber piezoelectric filter, this study presents an efficient new strategy for wastewater treatment utilizing an accessible redox reaction with MoSe2 nanoflowers, which shows a strong oxidizing ability and permits the decomposition of dye molecules in dark environments without the need for an external power source. By mixing molybdenum diselenide (MoSe2) and hydrogen peroxide (H2O2) solution, extremely non-equilibrium thermodynamics mixed oxidation of selenic acid (H2SeO4) and selenious acid (H2SeO3) solution is formed (referred to as MS oxidized solution). This MS oxidized solution can treat wastewater at a kinetic constant (kobs) above 0.65, which is 65 times higher than titanium dioxide photocatalysis. Even when interacting with organic pollutants at concentrations up to 1500 ppm, the kobs can reach 0.077 min-1. More importantly, the residual waste solution could be further utilized as a precursor to reconstruct the MoSe2 nanoflowers. To demonstrate the effectiveness and reusability, the treated effluent was directly used as the sole source of irrigated water for plants with no adverse effect. This method offers an eco-friendly and more accessible way to treat industrial wastewater with zero discharge, providing a new horizon for the organic wastewater treatment field.

1. Shannon, M.A., et al., Science and technology for water purification in the coming decades. Nanoscience and technology: a collection of reviews from nature Journals, 2010: p. 337-346.
2. Rice, J. and P. Westerhoff, High levels of endocrine pollutants in US streams during low flow due to insufficient wastewater dilution. Nature Geoscience, 2017. 10(8): p. 587-591.
3. Sun, Z., et al., Toward sustainability for recovery of critical metals from electronic waste: the hydrochemistry processes. ACS Sustainable Chemistry & Engineering, 2017. 5(1): p. 21-40.
4. Sena, M. and A. Hicks, Life cycle assessment review of struvite precipitation in wastewater treatment. Resources, Conservation and Recycling, 2018. 139: p. 194-204.
5. Tang, F.H., et al., Risk of pesticide pollution at the global scale. Nature Geoscience, 2021. 14(4): p. 206-210.
6. O’Connell, D.W., C. Birkinshaw, and T.F. O’Dwyer, Heavy metal adsorbents prepared from the modification of cellulose: A review. Bioresource technology, 2008. 99(15): p. 6709-6724.
7. Luo, T., S. Abdu, and M. Wessling, Selectivity of ion exchange membranes: A review. Journal of membrane science, 2018. 555: p. 429-454.
8. Feng, Y., et al., In-situ ion exchange electrocatalysis biological coupling (i-IEEBC) for simultaneously enhanced degradation of organic pollutants and heavy metals in electroplating wastewater. Journal of hazardous materials, 2019. 364: p. 562-570.
9. Ma, A., et al., Ion exchange homogeneous surface diffusion modelling by binary site resin for the removal of nickel ions from wastewater in fixed beds. Chemical Engineering Journal, 2019. 358: p. 1-10.
10. Pronk, W., et al., Gravity-driven membrane filtration for water and wastewater treatment: a review. Water research, 2019. 149: p. 553-565.
11. Fundneider, T., et al., Implications of biological activated carbon filters for micropollutant removal in wastewater treatment. Water Research, 2021. 189: p. 116588.
12. Chen, D., et al., Photocatalytic degradation of organic pollutants using TiO2-based photocatalysts: A review. Journal of Cleaner Production, 2020. 268: p. 121725.
13. Yu, M., et al., Intimate coupling of photocatalysis and biodegradation for wastewater treatment: mechanisms, recent advances and environmental applications. Water research, 2020. 175: p. 115673.
14. Fazal, T., et al., Bioremediation of textile wastewater and successive biodiesel production using microalgae. Renewable and Sustainable Energy Reviews, 2018. 82: p. 3107-3126.
15. Hodges, B.C., E.L. Cates, and J.-H. Kim, Challenges and prospects of advanced oxidation water treatment processes using catalytic nanomaterials. Nature nanotechnology, 2018. 13(8): p. 642-650.
16. Paździor, K., L. Bilińska, and S. Ledakowicz, A review of the existing and emerging technologies in the combination of AOPs and biological processes in industrial textile wastewater treatment. Chemical Engineering Journal, 2019. 376: p. 120597.
17. Miklos, D.B., et al., Evaluation of advanced oxidation processes for water and wastewater treatment–A critical review. Water research, 2018. 139: p. 118-131.
18. Ji, X., et al., Capturing functional two-dimensional nanosheets from sandwich-structure vermiculite for cancer theranostics. Nature communications, 2021. 12(1): p. 1-17.
19. Ji, X., et al., 2D Black Mica Nanosheets: Synthesis of Ultrathin Biotite Nanosheets as an Intelligent Theranostic Platform for Combination Cancer Therapy (Adv. Sci. 19/2019). Advanced Science, 2019. 6(19): p. 1970118.
20. Crini, G. and E. Lichtfouse, Advantages and disadvantages of techniques used for wastewater treatment. Environmental Chemistry Letters, 2019. 17(1): p. 145-155.
21. Khan, F.S.A., et al., A comprehensive review on magnetic carbon nanotubes and carbon nanotube-based buckypaper-heavy metal and dyes removal. Journal of Hazardous Materials, 2021: p. 125375.
22. Xu, J., et al., Organic wastewater treatment by a single-atom catalyst and electrolytically produced H 2 O 2. Nature Sustainability, 2021. 4(3): p. 233-241.
23. Brillas, E., I. Sirés, and M.A. Oturan, Electro-Fenton process and related electrochemical technologies based on Fenton’s reaction chemistry. Chemical reviews, 2009. 109(12): p. 6570-6631.
24. Martínez-Huitle, C.A. and E. Brillas, Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods: a general review. Applied Catalysis B: Environmental, 2009. 87(3-4): p. 105-145.
25. Moreira, F.C., et al., Electrochemical advanced oxidation processes: a review on their application to synthetic and real wastewaters. Applied Catalysis B: Environmental, 2017. 202: p. 217-261.
26. Zhao, Y., et al., Two-dimensional photocatalyst design: A critical review of recent experimental and computational advances. Materials Today, 2020. 34: p. 78-91.
27. Shayegan, Z., C.-S. Lee, and F. Haghighat, TiO2 photocatalyst for removal of volatile organic compounds in gas phase–A review. Chemical Engineering Journal, 2018. 334: p. 2408-2439.
28. Wu, J.M., et al., Piezo‐catalytic effect on the enhancement of the ultra‐high degradation activity in the dark by single‐and few‐layers MoS2 nanoflowers. Advanced Materials, 2016. 28(19): p. 3718-3725.
29. Chung, Y.J., et al., Coupling effect of piezo–flexocatalytic hydrogen evolution with hybrid 1T‐and 2H‐phase few‐layered MoSe2 nanosheets. Advanced Energy Materials, 2020. 10(42): p. 2002082.
30. Starr, M.B. and X. Wang, Coupling of piezoelectric effect with electrochemical processes. Nano Energy, 2015. 14: p. 296-311.
31. Hong, D., et al., High piezo-photocatalytic efficiency of CuS/ZnO nanowires using both solar and mechanical energy for degrading organic dye. ACS Applied Materials & Interfaces, 2016. 8(33): p. 21302-21314.
32. Hou, J.-T., et al., Fluorescent detectors for hydroxyl radical and their applications in bioimaging: a review. Coordination Chemistry Reviews, 2020. 421: p. 213457.
33. Baloyi, J., T. Ntho, and J. Moma, Synthesis and application of pillared clay heterogeneous catalysts for wastewater treatment: a review. RSC Adv 8: 5197–5211. 2018.
34. Kehrein, P., et al., A critical review of resource recovery from municipal wastewater treatment plants–market supply potentials, technologies and bottlenecks. Environmental Science: Water Research & Technology, 2020. 6(4): p. 877-910.
35. Wu, M.-H., et al., Ultrahigh efficient degradation activity of single-and few-layered MoSe2 nanoflowers in dark by piezo-catalyst effect. Nano Energy, 2017. 40: p. 369-375.
36. Liang, Z., et al., Piezoelectric materials for catalytic/photocatalytic removal of pollutants: Recent advances and outlook. Applied Catalysis B: Environmental, 2019. 241: p. 256-269.
37. Wang, Y., et al., Piezo-catalysis for nondestructive tooth whitening. Nature communications, 2020. 11(1): p. 1-11.
38. Lin, Y.T., S.N. Lai, and J.M. Wu, Simultaneous piezoelectrocatalytic hydrogen‐evolution and degradation of water pollutants by quartz microrods@ few‐layered MoS2 hierarchical heterostructures. Advanced Materials, 2020. 32(34): p. 2002875.
39. Wu, J.M., et al., Piezoelectricity induced water splitting and formation of hydroxyl radical from active edge sites of MoS2 nanoflowers. Nano Energy, 2018. 46: p. 372-382.
40. Starr, M.B. and X. Wang, Fundamental analysis of piezocatalysis process on the surfaces of strained piezoelectric materials. Scientific Reports, 2013. 3(1): p. 1-8.
41. Li, H., et al., Enhanced ferroelectric-nanocrystal-based hybrid photocatalysis by ultrasonic-wave-generated piezophototronic effect. Nano letters, 2015. 15(4): p. 2372-2379.
42. Xue, X., et al., Piezo-potential enhanced photocatalytic degradation of organic dye using ZnO nanowires. Nano Energy, 2015. 13: p. 414-422.
43. Ali, A., et al., Stimulated piezotronical decontamination using Cu2MgSnS4 modified BaTiO3. Materials Today Energy, 2021. 21: p. 100717.
44. Chou, T.-M., et al., A highly efficient Au-MoS2 nanocatalyst for tunable piezocatalytic and photocatalytic water disinfection. Nano Energy, 2019. 57: p. 14-21.
45. Masimukku, S., et al., High efficient degradation of dye molecules by PDMS embedded abundant single-layer tungsten disulfide and their antibacterial performance. Nano Energy, 2018. 46: p. 338-346.
46. Hu, C., et al., Exceptional Cocatalyst‐Free Photo‐Enhanced Piezocatalytic Hydrogen Evolution of Carbon Nitride Nanosheets from Strong In‐Plane Polarization. Advanced Materials, 2021: p. 2101751.
47. Wang, Y.C. and J.M. Wu, Effect of controlled oxygen vacancy on H2‐production through the piezocatalysis and piezophototronics of ferroelectric R3C ZnSnO3 nanowires. Advanced Functional Materials, 2020. 30(5): p. 1907619.
48. Wu, W., et al., Piezoelectricity of single-atomic-layer MoS 2 for energy conversion and piezotronics. Nature, 2014. 514(7523): p. 470-474.
49. Srinivaas, M., et al., Highly Rich 1T Metallic Phase of Few-Layered WS2 Nanoflowers for Enhanced Storage of Lithium-Ion Batteries. ACS Sustainable Chemistry & Engineering, 2019. 7(12): p. 10363-10370.
50. Shi, J., et al., Piezocatalytic foam for highly efficient degradation of aqueous organics. Small Science, 2021. 1(2): p. 2000011.
51. Osseiran, N. 2.1 billion people lack safe drinking water at home, more than twice as many lack safe sanitation. 2017 [cited 2017 2017].
52. Fujishima, A. and K. Honda, Electrochemical photolysis of water at a semiconductor electrode. nature, 1972. 238(5358): p. 37-38.
53. Mian, M.M. and G. Liu, Recent progress in biochar-supported photocatalysts: synthesis, role of biochar, and applications. RSC advances, 2018. 8(26): p. 14237-14248.
54. Schneider, J., et al., Photocatalysis: fundamentals and perspectives. 2016: Royal Society of Chemistry.
55. Nakata, K. and A. Fujishima, TiO2 photocatalysis: Design and applications. Journal of photochemistry and photobiology C: Photochemistry Reviews, 2012. 13(3): p. 169-189.
56. Szilágyi, I.M., et al., WO3 photocatalysts: Influence of structure and composition. Journal of catalysis, 2012. 294: p. 119-127.
57. Qi, K., et al., Review on the improvement of the photocatalytic and antibacterial activities of ZnO. Journal of Alloys and Compounds, 2017. 727: p. 792-820.
58. Cun, W., et al., Preparation, characterization and photocatalytic activity of nano-sized ZnO/SnO2 coupled photocatalysts. Applied Catalysis B: Environmental, 2002. 39(3): p. 269-279.
59. Mishra, M. and D.-M. Chun, α-Fe2O3 as a photocatalytic material: A review. Applied Catalysis A: General, 2015. 498: p. 126-141.
60. Bera, R., S. Kundu, and A. Patra, 2D hybrid nanostructure of reduced graphene oxide–CdS nanosheet for enhanced photocatalysis. ACS applied materials & interfaces, 2015. 7(24): p. 13251-13259.
61. Hu, J.S., et al., Mass production and high photocatalytic activity of ZnS nanoporous nanoparticles. Angewandte Chemie International Edition, 2005. 44(8): p. 1269-1273.
62. Etacheri, V., et al., Visible-light activation of TiO2 photocatalysts: Advances in theory and experiments. Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 2015. 25: p. 1-29.
63. Zhang, F., et al., Recent advances and applications of semiconductor photocatalytic technology. Applied Sciences, 2019. 9(12): p. 2489.
64. Zhang, X., et al., Plasmonic photocatalysis. Reports on Progress in Physics, 2013. 76(4): p. 046401.
65. Chen, J.-J., et al., Plasmonic photocatalyst for H2 evolution in photocatalytic water splitting. The Journal of Physical Chemistry C, 2011. 115(1): p. 210-216.
66. Xie, W., R. Li, and Q. Xu, Enhanced photocatalytic activity of Se-doped TiO 2 under visible light irradiation. Scientific reports, 2018. 8(1): p. 1-10.
67. Ou, G., et al., Tuning defects in oxides at room temperature by lithium reduction. Nature communications, 2018. 9(1): p. 1-9.
68. Bai, S., et al., Defect engineering in photocatalytic materials. Nano Energy, 2018. 53: p. 296-336.
69. Bai, S., et al., Facet‐engineered surface and interface design of photocatalytic materials. Advanced Science, 2017. 4(1): p. 1600216.
70. Li, M., et al., Ultrafine jagged platinum nanowires enable ultrahigh mass activity for the oxygen reduction reaction. Science, 2016. 354(6318): p. 1414-1419.
71. Nakajima, T., T. Tsuchiya, and T. Kumagai, Pulsed laser-induced oxygen deficiency at TiO2 surface: Anomalous structure and electrical transport properties. Journal of Solid State Chemistry, 2009. 182(9): p. 2560-2565.
72. Chen, X., et al., Increasing solar absorption for photocatalysis with black hydrogenated titanium dioxide nanocrystals. Science, 2011. 331(6018): p. 746-750.
73. Zhao, Z., et al., Effect of defects on photocatalytic activity of rutile TiO 2 nanorods. Nano Research, 2015. 8(12): p. 4061-4071.
74. Meng, S., et al., Insight into the transfer mechanism of photogenerated carriers for WO3/TiO2 heterojunction photocatalysts: is it the transfer of band–band or Z-scheme? Why? The Journal of Physical Chemistry C, 2018. 122(46): p. 26326-26336.
75. Zhang, Y., et al., Photocatalytic hydrogen evolution via water splitting: A short review. Catalysts, 2018. 8(12): p. 655.
76. Ahmad, H., et al., Hydrogen from photo-catalytic water splitting process: A review. Renewable and Sustainable Energy Reviews, 2015. 43: p. 599-610.
77. van de Krol, R., Y. Liang, and J. Schoonman, Solar hydrogen production with nanostructured metal oxides. Journal of Materials Chemistry, 2008. 18(20): p. 2311-2320.
78. Hong, K.-S., et al., Direct water splitting through vibrating piezoelectric microfibers in water. The journal of physical chemistry letters, 2010. 1(6): p. 997-1002.
79. Hu, C., et al., Exceptional cocatalyst‐free photo‐enhanced piezocatalytic hydrogen evolution of carbon nitride nanosheets from strong in‐plane polarization. Advanced Materials, 2021. 33(24): p. 2101751.
80. Li, Z., et al., Novel application of Ag/PbBiO2I nanocomposite in piezocatalytic degradation of rhodamine B via harvesting ultrasonic vibration energy. Ultrasonics sonochemistry, 2021. 78: p. 105729.
81. He, J., et al., C-Doped KNbO 3 single crystals for enhanced piezocatalytic intermediate water splitting. Environmental Science: Nano, 2022.
82. Liu, Y.-L. and J.M. Wu, Synergistically catalytic activities of BiFeO3/TiO2 core-shell nanocomposites for degradation of organic dye molecule through piezophototronic effect. Nano Energy, 2019. 56: p. 74-81.
83. Wang, Z., et al., Enhanced H2 production of TiO2/ZnO nanowires Co-using solar and mechanical energy through piezo-photocatalytic effect. ACS Sustainable Chemistry & Engineering, 2018. 6(8): p. 10162-10172.
84. Zhou, X., et al., Piezophototronic effect in enhancing charge carrier separation and transfer in ZnO/BaTiO3 heterostructures for high-efficiency catalytic oxidation. Nano Energy, 2019. 66: p. 104127.
85. Wang, M., et al., Remarkably enhanced hydrogen generation of organolead halide perovskites via piezocatalysis and photocatalysis. Advanced Energy Materials, 2019. 9(37): p. 1901801.
86. Tu, C.-Y. and J.M. Wu, Localized surface plasmon resonance coupling with piezophototronic effect for enhancing hydrogen evolution reaction with Au@ MoS2 nanoflowers. Nano Energy, 2021. 87: p. 106131.
87. Lin, M.-C., et al., Self-powered photoelectrochemical quartz/TiO2 microsystem through piezopotential sensitized photocatalytic process. Nano Energy, 2022. 91: p. 106640.
88. Becke, A.D., Density-functional exchange-energy approximation with correct asymptotic behavior. Physical review A, 1988. 38(6): p. 3098.
89. Lee, C., W. Yang, and R.G. Parr, Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Physical review B, 1988. 37(2): p. 785.
90. Halevy, R., et al., Electron spin resonance micro-imaging of live species for oxygen mapping. JoVE (Journal of Visualized Experiments), 2010(42): p. e2122.
91. Kanazawa, S., et al., Measurement of OH radicals in aqueous solution produced by atmospheric-pressure LF plasma jet. Int. J. Plasma Environ. Sci. Technol, 2012. 6(2): p. 166-171.
92. Lee, J.-T., M.-C. Lin, and J.M. Wu, High-efficiency cycling piezo-degradation of organic pollutants over three liters using MoS2/carbon fiber piezocatalytic filter. Nano Energy, 2022. 98: p. 107280.
93. Duerloo, K.-A.N., M.T. Ong, and E.J. Reed, Intrinsic piezoelectricity in two-dimensional materials. The Journal of Physical Chemistry Letters, 2012. 3(19): p. 2871-2876.
94. De-Nasri, S.J., et al., Quantification of hydroxyl radicals in photocatalysis and acoustic cavitation: Utility of coumarin as a chemical probe. Chemical Engineering Journal, 2021. 420: p. 127560.
95. Mushtaq, F., et al., Magnetoelectrically driven catalytic degradation of organics. Advanced Materials, 2019. 31(28): p. 1901378.
96. Chen, Z., et al., “The easier the better” preparation of efficient photocatalysts—metastable poly (heptazine imide) salts. Advanced Materials, 2017. 29(32): p. 1700555.
97. Keshavarzi, N., S. Cao, and M. Antonietti, A new conducting polymer with exceptional visible‐light photocatalytic activity derived from barbituric acid polycondensation. Advanced Materials, 2020. 32(16): p. 1907702.
98. Chen, S., et al., Triboelectric nanogenerator for sustainable wastewater treatment via a self‐powered electrochemical process. Advanced Energy Materials, 2016. 6(8): p. 1501778.
99. Huang, C., et al., Advances in self-powered chemical sensing via a triboelectric nanogenerator. Nanoscale, 2021. 13(4): p. 2065-2081.
100. Dai, C., et al., Novel MoSe 2 hierarchical microspheres for applications in visible-light-driven advanced oxidation processes. Nanoscale, 2015. 7(47): p. 19970-19976.
101. Shen, B., et al., Direct Chirality Recognition of Single‐Crystalline and Single‐Walled Transition Metal Oxide Nanotubes on Carbon Nanotube Templates. Advanced Materials, 2018. 30(44): p. 1803368.
102. Chandoul, F., et al., Change of the properties of nanostructured MoO3 thin films using gamma-ray irradiation. Ceramics International, 2018. 44(11): p. 12483-12490.
103. Kretzschmar, J., et al., Spectroscopic evidence for selenium (IV) dimerization in aqueous solution. Dalton Transactions, 2015. 44(22): p. 10508-10515.
104. Walrafen, G., Raman spectral studies of aqueous solutions of selenic acid. The Journal of Chemical Physics, 1963. 39(6): p. 1479-1492.
105. Lee, J.T., et al., MoSe2 nanoflowers for highly efficient industrial wastewater treatment with zero discharge. Advanced Science, 2021. 8(23): p. 2102857.
106. Diamantopoulou, A., et al., Titania photonic crystal photocatalysts functionalized by graphene oxide nanocolloids. Applied Catalysis B: Environmental, 2019. 240: p. 277-290.