A new ultra light composite aerogel absorbing material

With the rapid development of 5G communication technology and the widespread application of electronic devices, the impact of electromagnetic radiation on the environment is increasing day by day. Therefore, to control electromagnetic "pollution", we need to find a material that can absorb and weaken electromagnetic wave radiation——Absorbing materialIt has become a research hotspot in the field of functional materials.

Currently, absorbing materials are widely used in the fields of electromagnetic radiation protection and military stealth for household appliances, communication and medical equipment. For example, the electronic devices we use, such as laptops and mobile phones, contain internal componentsSurface mount absorbing materialIt can effectively absorb leaked electromagnetic radiation and eliminate electromagnetic interference. For example, coating the surfaces of weapons and equipment such as airplanes, missiles, and ships with absorbing materials can absorb reconnaissance radio waves, attenuate reflected signals, and thus break through the enemy's radar defense zone, becoming a powerful means of anti radar reconnaissance

As the smallest density solid material in the world at present, aerogel is a potential lightweight microwave absorbing material with unique three-dimensional porous network structure, huge specific surface area and ultra-low density.

Reduced graphene oxide is a new type of materialTwo dimensional carbon nanomaterialsAnd functionalized graphene. However, the single electromagnetic wave loss mechanism and poor impedance matching make it difficult for the electromagnetic absorption capability of reduced graphene oxide to meet practical application requirements.

Previous studies have shown that the assembly of two-dimensional reduced graphene oxide nanosheets into three-dimensional macro aerogels and further construction of graphene based magnetic composite aerogels with magnetic ferrites can not only greatly reduce the bulk density, improve the impedance matching between absorbers and air, but also achieve the synergy of multiple electromagnetic loss mechanisms.

In this study, the Advanced Institute of Science and Technology used graphene oxide nanosheets as templates, ethylene diamine as reducing agent and nitrogen dopant, and used solvothermal hydrothermal self-assembly two-step method to synthesize nitrogen doped graphene/hollow cobalt ferrite composite aerogels.

The scientific research of the Advanced Institute found that the composite aerogel has a unique three-dimensional hierarchical porous network structure and extremely low density (12.1~14.5 mg/cm3, about 9~11 times the air density). The electromagnetic parameters and microwave absorbing properties of composite aerogels can be effectively controlled by changing the morphology and addition amount of cobalt ferrite. Among them, when the addition amount of hollow cobalt ferrite is 15mg and the matching thickness is 1.8mm, the composite aerogel has the best wave absorption performance, which can simultaneously meet the practical application requirements of "thin thickness, strong absorption, broadband, low density and filling ratio".