Radiative Coupled Evaporation Cooling Hydrogel for Above-Ambient Heat Dissipation and Flame Retardancy

• An all-in-one photonic hydrogel integrates radiative and evaporative cooling for above-ambient heat dissipation and flame retardancy. • The REC hydrogel achieves a 12.0 °C lower temperature than a conventional radiative cooling film under identical outdoor daytime conditions. • Radiative cooling-assisted adsorption enables atmospheric water harvesting at night, ensuring sustained evaporative cooling during the day. • The hydrogel exhibits enhanced flame retardancy by absorbing heat without a corresponding temperature rise, mitigating fire risks in outdoor devices.