Sustainable chitosan derived 3D hierarchically porous carbon aerogel toward advanced infrared-radar compatibility

Simultaneously achieving infrared-radar compatibility in one material is an important challenge for multi-spectral compatible stealth technology. Chitosan-derived three-dimensional (3D) hierarchically porous carbon aerogel can effectively solve the problem. Inspired by floors-pillars concept, this work elaborately designed and successfully fabricated 3D skeletons consisted of two-dimensional (2D) sheets and one-dimensional (1D) struts. Benefiting from esterification and directional freeze drying method, the entire network could provide sufficient space for reducing thermal conductivity and motivating dipole polarization sites. Thanks to the facile calcination process, conductive components could be obtained, which guarantee low infrared (IR) emissivity and high conduction loss performance. In this work, the as-prepared carbon aerogel with ultra-low density of 0.005 g·cm-3 exhibits superb infrared stealth property. It shows a low thermal conductivity coefficient of only 0.0933 W·m-1·K-1. In addition, the heating rate of the upper surface is slow when placed on a heating platform of 60 oC. The relevant IR emissivity value is as low as 0.563 in 3-5 μm band and 0.432 in 8-14 μm band. Under relatively thin thicknesses, the prominent radar stealth performance including the optimum reflection loss value of -75.90 dB, the maximum effective bandwidth of 3.93 GHz, and the simulated radar cross section reduction value of 27.66 dB m2, can be obtained. This study not only introduces innovative design ideas but also offers technical approaches, facilitating further development in the realm of infrared-radar compatible stealth.