Regulating Cold Energy from the Universe by Bifunctional Phase Change Materials for Sustainable Cooling

Abstract

Harvesting cold energy from the universe by radiative cooling (RC) is a promising zero-carbon route for green cooling. However, low power density and spatiotemporal energy mismatch of RC are great challenges for realizing efficient space cooling. Herein, a facile strategy for regulating cold energy from the universe by bifunctional phase change materials (PCM) for sustainable cooling is proposed. A bifunctional phase-change composite film (PCCF) by integrating RC coating with PCM for 24-h cold energy harvesting, storage, and utilization is demonstrated. The bifunctional PCCF can harvest cold energy from the universe and regulate the redundant cold energy generated by nighttime RC to compensate for the cold shortage of daytime RC, realizing flexible regulation of all-day RC and setting new records of cooling power up to 180 W m⁻² with sub-ambient temperature drop of 11.95 °C. The work offers a promising strategy for zero-carbon sustainable cooling by maximizing RC with cold energy storage.