Electrospun poly(vinyl alcohol)/silica film for radiative cooling

Daytime radiative cooling materials have recently attracted tremendous interest by reflecting sunlight and radiating heat to the ultracold outer space without any energy consumption. While some progress has been made, it remains a big challenge in fabricating highly efficient, low-cost, biodegradable, and sustainable all-day radiative coolers. Here, we report a hierarchically structured poly(vinyl alcohol)/silica film via a facile electrospinning method. The diameters of the electrospun fibers range from several nanometers to several microns, and the silica particles distribute across the surface randomly. The optimal film exhibits sufficiently high solar reflectance (97%) and superior longwave infrared thermal emittance (95%), thus realizing sub-ambient cooling of ~ 9.3 °C during the night and ~ 4.5 to ~ 7.5 °C during the midday under the solar intensity of ~ 700 W/m 2 . Overall, this film demonstrates high performance of daytime radiative cooling, with an inexpensive and environmental production way compared to those of state-of-the-art designs. Graphical abstract