Thin layer lightweight and ultrawhite hexagonal boron nitride nanoporous paints for daytime radiative cooling
Thin layer lightweight and ultrawhite hexagonal boron nitride nanoporous paints for daytime radiative cooling
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DOI：
10.1016/j.xcrp.2022.101058
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发表时间：
2022-10
影响因子：
8.9
通讯作者：
Andrea Felicelli;Ioanna Katsamba;Fernando Barrios;Yun Zhang;Ziqi Guo;J. Peoples;G. Chiu;X. Ruan
中科院分区：
文献类型：
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作者：
Andrea Felicelli;Ioanna Katsamba;Fernando Barrios;Yun Zhang;Ziqi Guo;J. Peoples;G. Chiu;X. Ruan
许多重量敏感的应用都需要薄而轻的辐射冷却涂料。然而，薄层很难实现高太阳光反射率。这项工作开发了超白六方氮化硼丙烯酸涂料，其太阳反射率达到 97.9%，天窗发射率达到 0.83，厚度仅为 150 μm，重量为 0.029 g/cm2，比以前的辐射冷却涂料显着减少。六方氮化硼的高折射率和纳米片形态使得米氏散射式高散射系数和瑞利散射式强后向散射的独特组合成为可能，44.3%的孔隙率提供了六方氮化硼和空气之间的高折射率对比度；所有这些都有助于通过薄涂层实现高太阳反射率。现场测试显示，在阳光直射下全日制冷，白天平均温度比环境温度低 5–6°C。我们的六方氮化硼丙烯酸涂料表现出与最新最佳技术相当的冷却性能，并且薄度和重量轻减少了许多实际应用的障碍。
Thin and lightweight radiative cooling paints are needed for many weight-sensitive applications. However, it is difficult to achieve high solar reflectance with thin layers. This work develops ultrawhite hBN-acrylic paints that achieve solar reflectance of 97.9% and sky window emissivity of 0.83 with only 150 μm thickness and 0.029 g/cm2weight, representing significant reductions from previous radiative cooling paints. The high refractive index and nanoplatelet morphology of hBN enable a unique combination of Mie scattering-like high scattering coefficient and Rayleigh scattering-like strong backscattering, and a porosity of 44.3% offers high refractive index contrast between hBN and air; all contribute to achieve high solar reflectance with a thin coating. Field tests show full daytime cooling under direct sunlight, reaching 5–6°C below ambient temperature on average during daylight hours. Our hBN-acrylic paint demonstrates comparable cooling performance with recent best technologies, and the thinness and light weight reduce barriers toward many practical applications.