A novel design for CoAl-LDH double hydroxides layers vertically decorating three-dimensional carbon foam for strengthening electromagnetic wave attenuation and flame retardancy

The high-performance electromagnetic wave (EMW) absorption materials usually rely on carbon-based materials to enhance dielectric loss, but its easily burning character at high temperatures severely limits its application in high-temperature and heat accumulation environments. How to simultaneously realize excellent EMW absorption and flame retardant in carbon-based materials remains a formidable challenge. Herein, we proposed a special composite design strategy in-situ decorating the insulating layered double hydroxide (CoAl-LDH) nanosheets with flame retardancy function on carbon foam skeleton via a simple one-step hydrothermal method. The optimal minimum reflection loss of −51.8 dB and an exceptionally broaden effective absorption bandwidth (EAB) 5.2 GHz was achieved under absorber thickness 1.8 mm and 20% filling ratio. Taking current composite as pyramidal structure, the full-band absorption from 2 to 40 GHz not only was achieved, but also the anti-combustion effect in 220°C was retained. With insulated CoAl-LDH nanosheets vertically decorating on carbon skeleton, the restriction of long-range electron in carbon skeleton was demonstrated to enhance a dominant dielectric loss, which support the excellent EMW absorption. Together with interlayer water molecules and carbonate ions, the release of H 2 O and CO 2 from the hydroxides in the CoAl-LDH layers and the isolation heat transfer and oxygen from physical barrier was confirmed to contribute the flame-retardant properties. This work not only provides a novel strategy for designing high-performance EMW absorbers with integrated flame-retardant capabilities under about 220°C, but also open up a new perspective in utilizing localized carriers interaction to complete dielectric and combustion reaction regulation. Download: Download high-res image (439KB) Download: Download full-size image