An all-fiber Janus film with multi-band synergistic optical modulation for long-term efficient thermal management

Radiative cooling and solar heating are recognized as green and sustainable passive thermal management technologies that can significantly reduce global energy and environmental burdens. However, current thermal management materials are usually based on single-band optical modulation and rely on the involvement of inorganic nanoparticles, making them less effective for coping with long-lasting dynamic seasonal and weather changes. A comprehensive investigation into the overall CO₂ mitigation potential remains lacking. Herein, an all-fiber fabric with integrated heating and cooling functions is developed for long-term and efficient thermal management. The cooling layer composed of PVDF-HFP/PDMS hybrid microfibers allows maximum scattering of sunlight leading to ultrahigh reflectance of 98.9%, while the heating layer, composed of carbon nanofibers, minimized scattered sunlight and attenuated infrared vibrations. This fabric allows switchable solar reflectance (97%) and IR emittance (25%) by flipping, resulting in ∼5.8°C sub-ambient cooling and ∼35.2°C super-ambient heating under ∼73 mW/cm². Furthermore, it has a higher annual energy savings of ∼13.0 MJ/(m²·year) in midlatitude regions compared to conventional concrete, and achieves CO₂ reductions of 6.3–27.9 kg-CO₂eq over its service life. The all-fiber structure offers high adaptability to practical application environments and presents a promising solution in zero-energy thermal management in dynamic and multifarious complex scenarios.