Hierarchical Gradient Structural Porous Metamaterial with Selective Spectral Response for Daytime Passive Radiative Cooling

• DOI: 10.1002/adfm.202406393
• Publication Date: 2024-06-05T05:20:55Z
• Authors: Jinru Liu; Yuqi Wei; Yi Zhong; Linping Zhang; Bijia Wang; Xueling Feng; Hong Xu; Zhiping Mao
• Keywords: Radiative Cooling; Temperature Gradient

Abstract Porous photonic structures have greatly advanced large‐scale radiative cooling application owing to its satisfying optical properties, easy‐designation, and low cost. However, current reported porous materials mainly focuses on uniform or random pore distribution structure, which failed achieve precise spectrum control for sunlight mid‐infrared light, thereby weakening the performance. Herein, gradient structural metamaterials (GSPMs) are proposed successfully constructed maximizing effectiveness based step‐by‐step freeze‐casting technology. The designed GSPMs with micro‐nano structure can wide‐range scatter entire solar while possess gradual refractive index transition increase air‐medium interface absorption at regions. Notably, reflectivity emissivity of reach 97.3% 97.6%, achieving maxinum temperature 8.7 °C net power 94.1 W m −2 , presenting a higher effect than materials. Moreover, enable compatibility color aesthetic superiorities due selective spectra response behavior, as well be applied in building materials, realizing efficient energy saving CO 2 emission reduction. This work highly daytime cooling, offering new possibilities design next‐generation