Reducing the temperature of a solar probe or an orbital spacecraft has been successful in the spectral selectivity regime by maximizing the sunlight reflection and irradiating heat to the cold universe. Despite the extensive work on the adjustment of the absorbance/emissivity ratio, few efforts have been devoted to the modulation of heat conduction. In fact, the backlit-side of the spacecraft facing the cold universe is ideal for radiative cooling, as long as the sunlight generated heat is transferred effectively to the backlit surface with minimum heating of the interior structures. Here, by using a hexagonal-boron nitride (h-BN) and Al₂O₃ dual-layer coating, we demonstrate a strategy for space solar thermal shielding that combines radiative cooling and anisotropic thermal conduction. The in-plane alignment of the top-layer h-BN flakes to the coating surface leads to a highly anisotropic thermal diffusion behavior, enabling rapid in-plane heat transfer and effective out-of-plane thermal insulation. The spectral selectivity optimization allows the dual-layer coating to reflect nearly 89% of solar irradiation while having an emissivity greater than 0.86 across the thermal infrared wavelength. Moreover, the coating exhibits remarkable spectral stability under proton irradiation, showing its great potential in aerospace applications.

通过最大化太阳光的反射和向冷宇宙辐射热量，在光谱选择性方面成功地降低了太阳能探测器或轨道航天器的温度。尽管在吸收率/发射率比的调节方面进行了大量的工作，但很少有努力致力于热传导的调节。实际上，只要朝着寒冷的宇宙飞船的背光面是辐射冷却的理想选择，只要将太阳光产生的热量有效地传递到背光表面，并且内部结构的热量最少即可。在此，通过使用六方氮化硼（h-BN）和Al ₂ O ₃双层涂层，我们演示了结合辐射冷却和各向异性热传导的空间太阳热屏蔽策略。顶层h-BN薄片与涂层表面的面内排列会导致高度各向异性的热扩散行为，从而实现快速的面内传热和有效的面外隔热。光谱选择性的优化使双层涂层能够反射近89％的太阳辐射，同时在整个红外光谱范围内的发射率均大于0.86。此外，该涂层在质子辐照下显示出显着的光谱稳定性，显示了其在航空航天应用中的巨大潜力。