Dual Janus foam for directional thermal management

Directional thermal management is critical for energy harvesting and utilization. The common passive radiative cooling and heating strategies free of electricity input mainly focus on regulating the solar and thermal radiation properties of materials while neglecting the thermal conduction process. The directional thermal management for harvesting thermal energy based on the rare thermal rectifying materials is usually in the absence of radiation regulation. Here, the dual Janus foams with dual asymmetries in photothermal and thermal rectification are designed and exhibit high photothermal property contrast and excellent thermal rectification ratios (122 %). The temperature difference ratio of the managed end could be improved nearly 21 times from 3 % based on a single Janus structure to 65 % based on a dual Janus structure. This method provides a comprehensive and inspiring view for better directional thermal management in the future. Directional thermal management is critical for energy harvesting and the common passive radiative cooling and heating strategies free of electricity input focus on regulating the solar and thermal radiation properties of materials but neglect the thermal conduction process. Here, the authors report dual Janus foams with dual asymmetries in photothermal and thermal rectification showing high photothermal property contrast and thermal rectification ratios.