Self‐Sustaining Hybrid Passive Cooler Enabling Highly Effective Thermal Management for Outdoor Electronics

ABSTRACT Outdoor electronics serve as fundamental infrastructure in modern society, yet their reliable operation is critically challenged by simultaneous intense solar radiation and high‐power thermal shocks. To address this challenge, we proposed an innovative hybrid passive cooler (HPC) that integrates a porous vapor‐permeable radiative cooling coating and an autonomous atmospheric moisture‐harvesting hydrogel within a melamine sponge skeleton. A synergistic interplay of radiative cooling, sensible‐heat absorption, and latent‐heat evaporation is thus realized for exceptional outdoor electronics thermal management. Under continuous solar irradiation, the HPC enabled the heater to maintain a temperature of averaging 8.3°C below ambient air and achieve a maximum temperature drop of ∼42.4°C when further subjected to an intense thermal shock of 2000 W·m −2 for 30 min. Notably, by leveraging its autonomous atmospheric moisture‐harvesting capability, the HPC could consistently deliver stable and reliable thermal management performance for about 3 h with combined high thermal shock and solar radiation. Therefore, this work provides an efficient, sustainable, and scalable thermal management solution for outdoor electronics.