Professor Shu Ruiwen’s team of school of chemical engineering of Anhui University of Science and Technology synthesized nitrogen-doped graphene/hollow cobalt ferrite composite aerogel, which can be used for electromagnetic radiation “pollution” protection, electromagnetic interference shielding, military stealth, thermal insulation and fire prevention. The relevant research results were published in Materials Science and Technology.
Ultra-light nitrogen-doped graphene/hollow cobalt ferrite composite aerogel research group provided by the group
With the rapid development of 5G communication technology and the large number of applications of electronic equipment, the impact of electromagnetic wave radiation on the environment is increasing. Therefore, controlling electromagnetic “pollution” and finding a material that can absorb and weaken electromagnetic wave radiation – absorbing materials have become research hotspots in the field of functional materials.
At present, absorbing materials are widely used in household appliances, communications and medical equipment electromagnetic radiation protection and military stealth fields. “For example, the electronic devices we use, such as laptops and mobile phones, contain patch-type absorbing materials inside, which can effectively absorb the leakage of electromagnetic radiation and eliminate electromagnetic interference.” For example, coating the surface of aircraft, missiles, ships and other weapons and equipment with wave-absorbing materials can absorb reconnaissance radio waves and attenuate reflected signals, thereby breaking through the enemy’s radar defense zone and becoming a powerful means of anti-radar reconnaissance. Shu Ruiwen introduced to China Science Daily.
As the world’s least dense solid material – aerogel, it has a unique three-dimensional porous network structure, huge specific surface area and ultra-low density, and is a potential lightweight absorbing material.
Reducing graphene oxide is a new type of two-dimensional carbon nanomaterial and functional graphene. However, the single electromagnetic wave loss mechanism and poor impedance matching make it difficult to meet the actual application needs of the electromagnetic absorption ability of reduced graphene oxide.
Previous studies have shown that the assembly of two-dimensional reduced graphene oxide nanosheets into a three-dimensional macroscopic aerogel, and further the construction of graphene-based magnetic composite aerogel with magnetic ferrite, can not only greatly reduce the bulk density, improve the impedance matching degree between the absorbent and the air, but also achieve the synergy of multiple electromagnetic loss mechanisms.
In this study, The Shuriwen team synthesized a nitrogen-doped graphene/hollow cobalt ferrite composite aerogel using the graphene oxide nanosheets as a template, ethylenediamine as the reducing agent and nitrogen doping agent, and using the solvother-hydrothermal self-assembly two-step method.
It was found that the composite aerogel has a unique three-dimensional graded porous mesh structure and a very low density (12.1~14.5 mg/cm3, about 9 to 11 times the density of air). By changing the morphology and amount of cobalt ferrite, the electromagnetic parameters and absorption properties of the composite aerogel can be effectively regulated. Among them, when the addition amount of hollow cobalt ferrite is 15mg and the matching thickness is 1.8mm, the composite aerogel has the optimal absorption performance, which can meet the practical application needs of “thin thickness, strong absorption, wide frequency band, low density and filling ratio”.
The reviewers believe that the authors have prepared a new type of nitrogen-doped graphene/hollow cobalt ferrite composite aerogel by a simple method, which has a unique structure, excellent microwave absorption performance and lightweight characteristics, and has important guiding significance for the research and development of a new generation of lightweight and multifunctional electromagnetic absorbing materials. (Source: China Science Daily Wang Min)
Related paper information: https://doi.org/10.1016/j.jmst.2022.05.050