Synergistic Dual-Mode Cooling Enabled by h-BN/Al 2 O 3 Hybrid Composites for Efficient Thermal Management

. Field tests conducted over 2 days in Anseong, South Korea, demonstrate a peak subambient temperature drop of -12.4 °C and a stable average daily cooling performance of -10.2 °C, thereby demonstrating an almost 2-fold increase in efficiency compared to the control samples. This confirms the effective dispersion of heat throughout the 2 mm thick film, which enables bulk cooling beyond a mere surface effect. These findings represent a significant advancement for durable, self-standing passive cooling materials, with great potential for sustainable thermal management in various applications. While buildings and stationary electronics are canonical PDRC targets, mobile platforms such as unmanned aerial vehicles (UAVs) face acute solar heating with minimal allowance for active cooling or parasitic mass. The present dual-mode sheet is directly relevant to UAV outer skins: broadband solar backscattering curbs solar gain on sunlit surfaces, while the aligned h-BN network spreads internally generated heat through the 2 mm thickness and into the airstream. The electrically insulating, corrosion-resistant ceramic/epoxy architecture further suits composite airframes.