Poly(vinyl alcohol) composite nanofiber membranes with hydrophobicity for daytime radiative cooling

Daytime radiative cooling materials exhibit huge potential for sustainable development, which can reflect sunlight and radiate heat to outer space in the main atmospheric window without energy consumption. Recently, polymer-based nanofiber membranes have been fabricated for radiative cooling, because of their easy processing and ideal optical performance. However, there exist big challenges in fabricating low-cost and environmentally friendly daytime radiative cooling materials for large-scale practical applications. In this work, we demonstrate a novel poly(vinyl alcohol)@silica (PVA@SiO₂) composite membrane via typical electrospinning technology and a simple coating process. The resultant composite membrane exhibits spectral selectivity with high sunlight reflectance of ∼95.0 % as well as a mid-infrared emissivity of ∼90.2 %, UV protection, and hydrophobicity, endowing its excellent daytime radiative cooling effect with a temperature drop of ∼8.0 °C. The as-obtained membranes exhibit some promising future for the potential large-scale application of radiative cooling technology for energy savings.