Morphology‐Engineered CaCO 3 Enabling Dual‐Mode Nanocomposites for Zonal Radiative Cooling and Heating

Passive radiative cooling (PRC) and passive radiative heating (PRH) have emerged as promising strategies for low-energy temperature control technology. However, conventional materials fall short in addressing the challenges posed by regionalized thermal control. In response, a dual-mode film capable of delivering both high-performance PRC and PRH is demonstrated. On the cooling side, a gradient densified structure is constructed by precisely controlling the size distribution of spherical calcium carbonate (CaCO₃) and optimizing packing density within the PDMS matrix, resulting in a film with average solar reflectance of 95.2% and infrared emissivity of 96.7%. The heating side features a hierarchically structured PDMS/carbon nanotubes (CNTs) absorber templated from urchin-like CaCO₃, further integrates with a polyethylene terephthalate/indium tin oxide (PET/ITO) infrared suppression layer to enhance solar absorption and minimize thermal radiation losses. The heating side achieves an average 30.2% solar reflectance and 2.5% infrared emissivity, demonstrating its excellent radiative heating properties. The dual-mode film achieves average subambient cooling of 7.6 °C and heating of 3.6 °C under sunny and cloudy conditions. The synergistic enhancement of cooling and heating can be achieved by adjusting the orientation of each mode in building applications, providing a novel approach for a low-energy, high-efficiency, and intelligent building thermal control system.