Guide:
In this paper, a novel carbon nanotube / reduced graphene oxide aerogel absorbing material was developed and prepared by a simple in-situ hydrothermal method and freeze drying method.
The aerogel has extremely low density and achieves extremely high dielectric loss capability in the frequency range of 18–26.5 GHz. The strong absorption, wide absorption band, and thin and light performance make CNT / graphene aerogels have good application prospects in electromagnetic wave absorbing materials.
In recent years, due to the rapid development of the electronics industry and radio communication technology, the impact of electromagnetic radiation on human health and the environment has increased a lot more than in the past. In order to reduce electromagnetic pollution, electromagnetic wave absorbing materials are receiving more and more attention. Such materials can attenuate electromagnetic energy and convert it into heat energy through their inherent magnetic and dielectric losses. Nowadays, researchers have been making continuous efforts in material control strategies. These strategies are mainly to explore new materials or construct multiple functional components to achieve the maximum synergy of dielectric loss and magnetic loss. Compared with new materials (such as graphene, perovskite or MXenes), the use of multi-component synergistic control strategies to solve electromagnetic wave pollution is considered to be the most effective method, which not only expands the type of absorber, but also more easily Strong electromagnetic wave absorption ability.
Recently, many types of absorbing materials have been prepared by this strategy, especially for magnetic / dielectric composite materials, interface-based materials, etc., all showing ideal electromagnetic wave absorption capabilities. The shortcomings of the rate still greatly limit their commercial applications. The wave absorbing material is usually used in the form of a coating, which is composed of a wave absorbing filler and a matrix (ie paraffin, silicone, etc.). Usually in order to obtain the desired performance, the content of the absorbing filler is usually greater than 50 wt% (some even more than 80 wt%). In addition, these absorbers contain metals (such as iron carbonyl, FeCo-based alloys, etc.), so this will cause the density of the absorber to be too high. Faced with this difficulty, researchers' interest in porous carbon-based lightweight absorbing materials is increasing. For example, three-dimensional scaffold-like carbon aerogels have received more and more attention in recent years. Although many achievements have been made in this regard, due to the high density of metal oxides or metals, the density of the prepared multi-component aerogel is not sufficiently reduced, and at the same time, the filling rate of the absorbent is still greater than 20 wt%.
In response to the above problems, researchers such as Hualiang Lv of Fudan University developed a new type of carbon nanotube / reduced graphene oxide aerogel (CNTs / GA) through a simple in-situ hydrothermal method and freeze-drying method Absorbing material. The prepared CNTs / GA absorbent has a porous three-dimensional (3D) network structure, which not only greatly enhances the electromagnetic wave absorption capacity, but also helps to form ultra-low density and conductive penetration thresholds. The results show that the absorber layer with 4 wt% absorber (CNTs / GA aerogel) shows excellent electromagnetic wave absorption capacity and maximized effective absorption bandwidth (effective thickness of 8.5 GHz at 1.7 mm thickness). This achievement provides a reference for the preparation of ultra-thin porous 3D aerogel absorbing materials composed of light components with wide band absorption and ultra-thin. Related work was published in the famous journal "Composites PartB: Engineering" with the title "Exceptionally porous three-dimensional architectural nanostructure derived from CNTs / grapheneaerogel towards the ultra-wideband EM absorption".
Paper link:
https://doi.org/10.1016/j.compositesb.2020.108122
In summary, an aerogel composed of CNT and reduced graphene oxide was easily prepared by hydrothermal method and freeze-drying method, in which CNT closely adhered to graphene nanosheets and formed a porous 3D structure. The aerogel has extremely low density and achieves extremely high dielectric loss capability in the frequency range of 18–26.5 GHz. When 4 wt% CNTs @ GA aerogel is dispersed in the PDMS matrix, the minimum reflection loss value at 1.7 mm is -31.0 dB at 22.4 GHz, and the effective absorption bandwidth covers the entire frequency range (18–26.5 GHz ). The strong absorption, wide absorption band, and thin and light performance make CNT / graphene aerogels have good application prospects in electromagnetic wave absorbing materials.