Jing Weilong, Zhang Shuai, Zhang Wei, Chen Zhang, Zhang Canying, Wu Daxiong, Gao Yanfeng, Zhu Haitao
College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao, Shandong 266042, P. R. China.
School of Materials Science and Engineering, Shanghai University, Shanghai 200444, P. R. China.
ACS Appl Mater Interfaces. 2021 Jun 16. doi: 10.1021/acsami.1c05364.
Daytime radiative cooling materials reflect solar light and dissipate heat directly to outer space without any energy consumption, and thus, have attracted much attention due to the potential applications in many fields. Recently, elaborately designed photonic crystal and metamaterials have been reported for daytime subambient radiative cooling. However, such materials and structures have the drawbacks of complex shapes, inflexibility, high cost, and limitation in scaling up. It is also extremely difficult to apply such materials to buildings, vehicles, and other objects having complex surfaces. Here, a scalable and flexible hybrid film for daytime subambient radiative cooling was fabricated by a facile electrospinning method. The hybrid film consists of poly(vinylidene fluoride)/alumina (PVDF/AlO) fibers with diameters of 0.5-2.5 μm. Owing to the efficient scattering by fibers and AlO nanoparticles, the hybrid film exhibits an extremely high average solar reflectance of 0.97. A high average atmospheric window emittance of 0.95 is simultaneously achieved due to the molecular vibrations of PVDF and the phonon polariton resonance of AlO nanoparticles. The composite film delivers an average net radiative cooling power of 82.7 W/m, and a temperature drop of up to 4.0 °C under direct sunlight. The hybrid film exhibits remarkable radiative cooling performance under different weather conditions including sunny, cloudy, overcast, and rainy. It can be used not only for cooling buildings and vehicles but also for delaying the melting of glaciers. This work demonstrates a promising method for scale-up production of the radiative cooling film with high performance.
日间辐射冷却材料能够反射太阳光并直接将热量耗散到外层空间，无需任何能量消耗，因此，因其在许多领域的潜在应用而备受关注。最近，已经报道了精心设计的光子晶体和超材料用于日间低于环境温度的辐射冷却。然而，这类材料和结构存在形状复杂、缺乏柔韧性、成本高以及扩大规模受限等缺点。将这类材料应用于建筑物、车辆和其他具有复杂表面的物体也极其困难。在此，通过一种简便的静电纺丝方法制备了一种用于日间低于环境温度辐射冷却的可扩展且灵活的混合薄膜。该混合薄膜由直径为0.5 - 2.5μm的聚偏氟乙烯/氧化铝（PVDF/AlO）纤维组成。由于纤维和AlO纳米颗粒的有效散射，该混合薄膜表现出极高的平均太阳反射率，达到0.97。由于PVDF的分子振动和AlO纳米颗粒的声子极化激元共振，同时实现了0.95的高平均大气窗口发射率。该复合薄膜的平均净辐射冷却功率为82.7 W/m²，在直射阳光下温度可降低高达4.0°C。该混合薄膜在包括晴天、多云、阴天和雨天等不同天气条件下均表现出显著的辐射冷却性能。它不仅可用于建筑物和车辆的冷却，还可用于延缓冰川融化。这项工作展示了一种有前景的大规模生产高性能辐射冷却薄膜的方法。
