全球暖化導致冷卻需求持續增加，使用傳統冷卻手段如風扇、空調，除用電量提升外，設備排出之熱空氣亦加劇室外溫度上升，造成惡性循環。若使用被動輻射冷卻作為新興冷卻手段，藉由將熱能透過大氣窗口區域(波長8至13μm)向外太空散發輻射熱，無須消耗能量即可達成冷卻之效果。因此本研究擬利用輻射冷卻機制，盼以低成本之手段，製備輻射冷卻塗層，並提升輻射冷卻效能。實驗將分為三部分：(1) 開發自動化塗佈系統，建立穩定、可大量生產之塗層製程；(2) 了解機台塗佈性能，並開發低毒性、簡易之輻射冷卻塗層；(3) 加入高反射材料TiO2，以提升輻射冷卻塗層性能。各塗層之相關分析將以SEM、LSCM觀察表面形貌及粉體分布均勻度，並以UV-Vis-NIR、FTIR檢驗塗層反射率以及發射率，並且實際進行日曬實驗了解各塗層之降溫效果。結果顯示以0.4μm SiO2粉末、濃度15vol%所製備之IPA- SiO2-塗層可獲得單日最高15.5°C之降溫效果。以濃度10vol%塗佈不同厚度之塗層，以厚度100μm之塗層具有最佳降溫效果，單日最大降溫可達約13.5°C。最後，於漿料中添加高反射材料TiO2，可提升輻射冷卻效果，其中以10vol% SiO2 + 2vol% TiO2之漿料配比可獲得最大降溫13.8°C。本研究之輻射冷卻塗層具厚度可調、穩定生產，並且在實際之日曬實驗，與未塗佈之基板相比，皆有顯著之降溫冷卻效果。

Global warming has led to a continuous increase in cooling demand. Traditional cooling methods such as air conditioners consume more electricity with the discharge of hot air, causing a vicious cycle. As an emerging cooling method, by transferring the radiation into outer space through the atmospheric window, passive radiative cooling could achieve cooling effects without consuming energy. Therefore, this study aims to develop an automated coating system to assist the preparation of radiative cooling coatings and improve their efficiency via radiative cooling mechanisms. The study could be divided into three parts: (1) developing an automated coating system; (2) understanding its capability and developing low-toxicity radiative cooling coatings; and (3) adding reflective material to improve the performance of the radiative cooling coatings. The coatings are characterized using various techniques, such as SEM, LSCM, UV-Vis-NIR, and FTIR, to observe their powder uniformity, surface morphology, reflectance, and emissivity. Sun exposure experiments are conducted to examine the cooling effect. The results showed that the radiative cooling coating of IPA-SiO2 with a concentration of 15vol% could achieve a maximum temperature reduction of 15.5°C. Meanwhile, coatings with different thicknesses with a concentration of 10vol% showed that the coating with a thickness of 100μm had the best cooling effect, with a maximum temperature reduction of 13.5°C. Finally, adding high-reflectance material TiO2 to IPA-SiO2 coatings could improve the radiative cooling effect. With a ratio of 10 vol% SiO2 + 2 vol% TiO2, a maximum temperature reduction of 13.8°C could be achieved. In summary, in this study, we have developed radiative cooling coatings with adjustable thicknesses, and stable production. While significant cooling effects are demonstrated compared to non-coated substrates.

[1] J. Houghton, Rep. Prog. Phys., 68 (2005) 1343-1403.
[2] E.A. Goldstein, A.P. Raman, S. Fan, Nat Energy, 2 (2017) 1-7.
[3] Ipcc, Global Warming of 1.5°C: IPCC Special Report on impacts of global warming of 1.5°C above pre-industrial levels in context of strengthening response to climate change, sustainable development, and efforts to eradicate poverty, Cambridge University Press (2022).
[4] A.M. Rizwan, L.Y.C. Dennis, C. Liu, Journal of Environmental Sciences, 20 (2008) 120-128.
[5] K.C.S. Ly, X. Liu, X. Song, C. Xiao, P. Wang, H. Zhou, T. Fan, Adv. Funct. Mater., n/a (2022) 2203789.
[6] H. Nazarnia, M. Nazarnia, H. Sarmasti, W.O. Wills, Civ Eng J, 6 (2020) 1375-1399.
[7] Y. Zhu, H. Qian, R. Yang, D. Zhao, Solar Energy, 218 (2021) 195-210.
[8] Z.M. Zhang, Nano/Microscale Heat Transfer, Springer International Publishing (2020).
[9] W. Li, S. Fan, Optics & Photonics News, 30 (2019) 32.
[10] M.F. Modest, S. Mazumder, Radiative Heat Transfer, Academic Press (2021).
[11] G. Butcher, Tour of the Electromagnetic Spectrum, Government Printing Office (2016).
[12] Y. Cui, X. Luo, F. Zhang, L. Sun, N. Jin, W. Yang, Particuology, 67 (2022) 57-67.
[13] B. Zhao, M. Hu, X. Ao, G. Pei, Appl. Therm. Eng., 155 (2019) 660-666.
[14] J.P. Bijarniya, J. Sarkar, P. Maiti, Renewable and Sustainable Energy Reviews, 133 (2020) 110263.
[15] W.H. Organization, Environmental Health Criteria 14. Ultraviolet radiation., (1979).
[16] J. Peoples, X. Li, Y. Lv, J. Qiu, Z. Huang, X. Ruan, Int. J. Heat Mass Transfer, 131 (2019) 487-494.
[17] C. Riordan, R. Hulstron, in: IEEE Conference on Photovoltaic Specialists, 1990, pp. 1085-1088 vol.1082.
[18] T.M. Crawford, C.E. Duchon, J. Appl. Meteor., 38 (1999) 474-480.
[19] T.S. Eriksson, C.G. Granqvist, Appl. Opt., 21 (1982) 4381-4388.
[20] D. Zhao, A. Aili, Y. Zhai, S. Xu, G. Tan, X. Yin, R. Yang, Applied Physics Reviews, 6 (2019) 021306.
[21] X. Yin, R. Yang, G. Tan, S. Fan, Science, 370 (2020) 786-791.
[22] G. Kirchhoff, Über das Verhältnis zwischen dem Emissionsvermögen und dem Absorptionsvermögen der Körper für Wärme und Licht, in: Von Kirchhoff bis Planck, Springer, 1978, pp. 131-151.
[23] G.S. Ranganath, Resonance, 13 (2008) 115-133.
[24] M.M. Hossain, M. Gu, Advanced Science, 3 (2016) 1500360.
[25] C. Liu, Y. Wu, B. Wang, C. Zhao, H. Bao, Solar Energy, 183 (2019) 218-225.
[26] J. Liu, J. Zhang, D. Zhang, S. Jiao, J. Xing, H. Tang, Y. Zhang, S. Li, Z. Zhou, J. Zuo, Renewable and Sustainable Energy Reviews, 130 (2020) 109935.
[27] B. Zhao, M. Hu, X. Ao, N. Chen, G. Pei, Applied Energy, 236 (2019) 489-513.
[28] N.N. Shi, C.-C. Tsai, F. Camino, G.D. Bernard, N. Yu, R. Wehner, Science, 349 (2015) 298-301.
[29] W. Wu, S. Lin, M. Wei, J. Huang, H. Xu, Y. Lu, W. Song, Sol. Energy Mater. Sol. Cells, 210 (2020) 110512.
[30] A.R. Gentle, G.B. Smith, Nano Lett., 10 (2010) 373-379.
[31] W. Li, Y. Li, K.W. Shah, Solar Energy, 207 (2020) 247-269.
[32] A.W. Harrison, M.R. Walton, Solar Energy, 20 (1978) 185-188.
[33] A.P. Raman, M.A. Anoma, L. Zhu, E. Rephaeli, S. Fan, Nature, 515 (2014) 540-544.
[34] X. Yu, J. Chan, C. Chen, Nano Energy, 88 (2021) 106259.
[35] M. Muselli, D. Beysens, J. Marcillat, I. Milimouk, T. Nilsson, A. Louche, Atmospheric Research, 64 (2002) 297-312.
[36] A.F.G. Jacobs, B.G. Heusinkveld, S.M. Berkowicz, Atmospheric Research, 87 (2008) 377-385.
[37] B. Zhao, C. Wang, M. Hu, X. Ao, J. Liu, Q. Xuan, G. Pei, Energy, 238 (2022) 121761.
[38] Z. Yi, Y. lv, D. Xu, J. Xu, H. Qian, D. Zhao, R. Yang, Energy and Built Environment, 2 (2021) 214-222.
[39] C. Feng, P. Yang, H. Liu, M. Mao, Y. Liu, T. Xue, J. Fu, T. Cheng, X. Hu, H.J. Fan, K. Liu, Nano Energy, 85 (2021) 105971.
[40] J. Mandal, Y. Yang, N. Yu, A.P. Raman, Joule, 4 (2020) 1350-1356.
[41] B. Zhao, M. Hu, X. Ao, G. Pei, Applied Energy, 205 (2017) 626-634.
[42] S. Cui, C. Ahn, M.C. Wingert, D. Leung, S. Cai, R. Chen, Applied Energy, 168 (2016) 332-339.
[43] A.R. Gentle, G.B. Smith, Advanced Science, 2 (2015) 1500119.
[44] R. Family, M.P. Mengüç, Procedia Environmental Sciences, 38 (2017) 752-759.
[45] M. Hu, B. Zhao, Suhendri, X. Ao, J. Cao, Q. Wang, S. Riffat, Y. Su, G. Pei, Renewable and Sustainable Energy Reviews, 160 (2022) 112304.
[46] K. Wang, G. Luo, X. Guo, S. Li, Z. Liu, C. Yang, Solar Energy, 225 (2021) 245-251.
[47] H. Zhang, K.C.S. Ly, X. Liu, Z. Chen, M. Yan, Z. Wu, X. Wang, Y. Zheng, H. Zhou, T. Fan, Proceedings of the National Academy of Sciences, 117 (2020) 14657-14666.
[48] J. Li, Y. Liang, W. Li, N. Xu, B. Zhu, Z. Wu, X. Wang, S. Fan, M. Wang, J. Zhu, Sci. Adv., 8 (2022) eabj9756.
[49] X. Wang, X. Liu, Z. Li, H. Zhang, Z. Yang, H. Zhou, T. Fan, Adv. Funct. Mater., 30 (2020) 1907562.
[50] P.-C. Hsu, A.Y. Song, P.B. Catrysse, C. Liu, Y. Peng, J. Xie, S. Fan, Y. Cui, Science, 353 (2016) 1019-1023.
[51] L. Cai, Y. Peng, J. Xu, C. Zhou, C. Zhou, P. Wu, D. Lin, S. Fan, Y. Cui, Joule, 3 (2019) 1478-1486.
[52] A.P. Raman, W. Li, S. Fan, Joule, 3 (2019) 2679-2686.
[53] L. Zhou, H. Song, J. Liang, M. Singer, M. Zhou, E. Stegenburgs, N. Zhang, C. Xu, T. Ng, Z. Yu, B. Ooi, Q. Gan, Nat Sustain, 2 (2019) 718-724.
[54] M.A. Kecebas, M.P. Menguc, A. Kosar, K. Sendur, J. Quant. Spectrosc. Radiat. Transfer, 198 (2017) 179-186.
[55] E. Rephaeli, A. Raman, S.H. Fan, Nano Lett., 13 (2013) 1457-1461.
[56] P. You, X. Li, Y. Huang, X. Ma, M. Pu, Y. Guo, X. Luo, Materials, 13 (2020) 2885.
[57] D. Chae, M. Kim, P.-H. Jung, S. Son, J. Seo, Y. Liu, B.J. Lee, H. Lee, ACS Appl. Mater. Interfaces, 12 (2020) 8073-8081.
[58] J.L. Kou, Z. Jurado, Z. Chen, S.H. Fan, A.J. Minnich, Acs Photonics, 4 (2017) 626-630.
[59] Y. Yang, L. Long, S. Meng, N. Denisuk, G. Chen, L. Wang, Y. Zhu, Sol. Energy Mater. Sol. Cells, 211 (2020) 110548.
[60] M.M. Hossain, B. Jia, M. Gu, Advanced Optical Materials, 3 (2015) 1047-1051.
[61] S.Y. Jeong, C.Y. Tso, Y.M. Wong, C.Y.H. Chao, B. Huang, Sol. Energy Mater. Sol. Cells, 206 (2020) 110296.
[62] C. Ziming, W. Fuqiang, G. Dayang, L. Huaxu, S. Yong, Sol. Energy Mater. Sol. Cells, 213 (2020) 110563.
[63] Y. Zhai, Y. Ma, S.N. David, D. Zhao, R. Lou, G. Tan, R. Yang, X. Yin, Science, 355 (2017) 1062-1066.
[64] Z. Cheng, Y. Shuai, D. Gong, F. Wang, H. Liang, G. Li, Sci. China Technol. Sci., 64 (2021) 1017-1029.
[65] X. Li, J. Peoples, P. Yao, X. Ruan, ACS Appl. Mater. Interfaces, 13 (2021) 21733-21739.
[66] Y. Liu, S. Son, D. Chae, P.-H. Jung, H. Lee, Sol. Energy Mater. Sol. Cells, 213 (2020) 110561.
[67] Z. Huang, X. Ruan, Int. J. Heat Mass Transfer, 104 (2017) 890-896.
[68] G. Chen, Y. Wang, J. Qiu, J. Cao, Y. Zou, S. Wang, D. Jia, Y. Zhou, ACS Appl. Mater. Interfaces, 12 (2020) 54963-54971.
[69] J. Mandal, Y.K. Fu, A.C. Overvig, M.X. Jia, K.R. Sun, N.N. Shi, H. Zhou, X.H. Xiao, N.F. Yu, Y. Yang, Science, 362 (2018) 315-318.
[70] D. Li, X. Liu, W. Li, Z. Lin, B. Zhu, Z. Li, J. Li, B. Li, S. Fan, J. Xie, J. Zhu, Nat. Nanotechnol., 16 (2021) 153-158.
[71] T. Li, Y. Zhai, S.M. He, W.T. Gan, Z.Y. Wei, M. Heidarinejad, D. Dalgo, R.Y. Mi, X.P. Zhao, J.W. Song, J.Q. Dai, C.J. Chen, A. Aili, A. Vellore, A. Martini, R.G. Yang, J. Srebric, X.B. Yin, L.B. Hu, Science, 364 (2019) 760-+.
[72] B. Xiang, R. Zhang, Y. Luo, S. Zhang, L. Xu, H. Min, S. Tang, X. Meng, Nano Energy, 81 (2021) 105600.
[73] 施薇雅, 碩士論文, 用於日間輻射冷卻應用的軟質材料工程,國立台灣大學 (2021).
[74] T. Wang, Y. Wu, L. Shi, X. Hu, M. Chen, L. Wu, Nat Commun, 12 (2021) 365.
[75] J. Mandal, M. Jia, A. Overvig, Y. Fu, E. Che, N. Yu, Y. Yang, Joule, 3 (2019) 3088-3099.
[76] D. Lee, M. Go, S. Son, M. Kim, T. Badloe, H. Lee, J.K. Kim, J. Rho, Nano Energy, 79 (2021) 105426.
[77] H. Zhao, Q. Sun, J. Zhou, X. Deng, J. Cui, Adv. Mater., 32 (2020) 2000870.
[78] H. Bao, C. Yan, B. Wang, X. Fang, C.Y. Zhao, X. Ruan, Sol. Energy Mater. Sol. Cells, 168 (2017) 78-84.
[79] 陳品璇, 碩士論文, 聚甲基丙烯酸甲酯塗層的製備與性質分析於輻射冷卻之應用, 台科大 (2021).
[80] 陳怡蓁, 碩士論文, 製備與分析應用於輻射冷卻之二氧化鈦-二氧化矽-聚甲基丙烯酸甲酯塗層,台科大 (2022).
[81] N.S. Claxton, T.J. Fellers, M.W. Davidson, Encyclopedia of Medical Devices and Instrumentation, 21 (2006) 1-37.