Spatially partitioned and spectrally decoupled radiative cooling integrated phase change composites for dynamic building thermal management

The static characteristics of passive radiative cooling (PRC) materials frequently result in nocturnal supercooling. Although the integration of phase change materials enables dynamic thermal management, the competition for physical space between radiative cooling units and phase change units in different integrated structures leads to a performance trade-off between the spectral characteristics of radiative cooling and the phase change enthalpy value. A double-layer radiative cooling-integrated phase change composite (DL-RCPCM) with spatial zoning design was developed in this study to break this limitation via spectral decoupling. The top radiative cooling layer triggers a scattering cascade via a multi-scale structural design, achieving a high solar reflectivity of 94.5% while providing a transparent optical window for the bottom layer radiation. A strong infrared emission network is constructed in the bottom heat storage layer via in-situ graft polymerization of anisotropic microtubular cavities in delignified wood with silicone gel, and efficient and stable encapsulation of PCMs is achieved simultaneously (166 J/g). A high synergistic emissivity of 93.2% is achieved by this architecture through spatial zoning and functional synergy. In outdoor tests, the DL-RCPCM achieved a temperature drop of 12.0 °C in the daytime and provided a thermal buffer of 2.7 °C at night via latent heat compensation. A novel strategy is provided by this study for the regulation of complex photon-phonon transport in carbon-neutral dynamic thermal regulators.