Color-preserving daytime passive radiative cooling based on Fe3+-doped Y2Ce2O7

Abstract

State-of-the-art materials for daytime passive radiative cooling (DPRC) often utilize a combination of solar reflector and infrared emitter in different structures, or even in expensive nanofabricated photonic structures, which limits their practical applications. In this study, pure Y2Ce2O7 is prepared by Sol-Gel method to realize DPRC. More attracting, the aesthetic performance of Y2Ce2O7 is modified by doping Fe3+ ions to regulate its color from ivory white to darker ones, realizing color-preserving DPRC. The high solar reflection and strong thermal infrared emission of a series of Y2Ce2-xFexO7+δ are caused by the high bandgap within solar spectrum and lattice strain and distortion of various bonds (e.g., Y-O, Ce-O), respectively. When using Y2Ce2-xFexO7+δ as a coating on a building in a hot season, the aesthetic of the building becomes better due to the darker color and the cooling performance is weaker with x increasing, indicating a tradeoff between energy saving and human aesthetics. According to the simulated results, the Y2Ce2O7 and Y2Ce1.9Fe0.1O7 coatings save 50.0% and 21.9% energy consumption compared with similar-colored coatings, respectively. Without expensive nanofabrication process, this series of Y2Ce2-xFexO7+δ provide new promising selections to develop buildings with the harmony of energy saving and human aesthetics.