In the modern society where electromagnetic interference is becoming increasingly severe,
Absorbing materialResearch and development have become crucial. Graphene, with its excellent electrical, mechanical, and thermal properties, has shown great potential in the field of absorbing materials. Exploring the correlation between the absorption performance of graphene absorbing materials and the content and number of graphene layers is of great significance for optimizing the performance of absorbing materials and promoting their widespread application.
The unique structure and absorption principle of graphene
Graphene is a two-dimensional carbon nanomaterial composed of carbon atoms in sp ² hybridized orbitals, forming a hexagonal honeycomb lattice. Its unique two-dimensional planar structure endows it with high specific surface area and good conductivity. When electromagnetic waves are incident on the surface of graphene, a portion of the waves will be reflected, while another portion will enter the interior of graphene. Due to the high conductivity of graphene, electromagnetic waves entering the interior will generate induced currents in graphene. According to Joule's law, the current passing through a resistor will generate heat, which converts electromagnetic energy into thermal energy and dissipates it, achieving absorption of electromagnetic waves.
The Influence of Graphene Content on Absorption Properties
Performance when the content is too low
When the content of graphene in the absorbing material is low, there are fewer effective media in the system that can supply electromagnetic waves. Limited graphene cannot form a sufficiently dense conductive network, and when electromagnetic waves propagate in the material, induced currents are difficult to effectively form, resulting in poor absorption performance. For example, in some polymer based systems
Graphene composite absorbing materialWhen the graphene content is less than 1%, the material's absorption loss for specific frequency bands of electromagnetic waves is only about 5dB, which is difficult to meet practical application requirements.
Improvement when the content is moderate
With the increase of graphene content, a continuous conductive network gradually forms in the material, and the interaction between electromagnetic waves and graphene is enhanced. Within an appropriate content range, such as 3% -5%, the material's absorption performance is significantly improved. At this point, the material's absorption loss of electromagnetic waves can reach over 15dB, and some frequency bands can even reach 20dB. This is because a sufficient amount of graphene enables the induced current to flow smoothly throughout the entire material system, effectively converting electromagnetic energy into thermal energy, thereby enhancing the absorption capacity of electromagnetic waves.
Disadvantages when the content is too high
However, when the graphene content is too high, agglomeration occurs. A large amount of aggregated graphene can disrupt the originally uniform microstructure of the material, leading to high electrical conductivity in local areas and causing impedance mismatch. This increases the reflection of electromagnetic waves on the surface of the material, making it difficult to penetrate deep into the material and be absorbed, thereby reducing the absorption performance. For example, when the graphene content exceeds 10%, the reflection loss of the material significantly increases and the absorption performance shows a downward trend.
The Influence of Graphene Layers on Absorption Properties
Characteristics of single-layer graphene
Single layer graphene has the most perfect two-dimensional planar structure, with its π electron cloud fully exposed and a more direct interaction with electromagnetic waves. In theory, single-layer graphene has a certain absorption capacity for electromagnetic waves, but due to its extremely thin thickness, its attenuation effect on electromagnetic waves is limited. In practical applications, single-layer graphene alone serves as
Absorbing materialAt that time, the absorption frequency band of electromagnetic waves is relatively narrow, and the absorption intensity is also relatively low.
Advantages of Multilayer Graphene
As the number of layers increases, π - π stacking interactions will form between graphene layers, which will alter the electronic structure of graphene and increase electron scattering centers. Multilayer graphene can interact with electromagnetic waves in a wider frequency range, thereby expanding the absorption frequency band. For example, graphene with 3-5 layers can exhibit good absorption performance in both the X-band (8-12 GHz) and Ku band (12-18 GHz), and compared to single-layer graphene, the absorption frequency band is significantly broadened. At the same time, the multi-layer structure also increases the propagation path of electromagnetic waves inside the material, giving it more opportunities to be absorbed and attenuated, thereby improving the absorption intensity.
The problem of too many layers
But when there are too many layers, the structure of graphene gradually tends to graphitize, and the electronic conductivity between layers is enhanced, resulting in an overall high electrical conductivity of the material, which can also cause impedance mismatch problems. At this point, electromagnetic waves are heavily reflected on the surface of the material, making it difficult for them to enter the interior and be effectively absorbed, resulting in a decrease in absorption performance. Research has shown that when the number of graphene layers exceeds 10, the material's absorption performance begins to deteriorate.
Graphene absorbing materialThe absorption performance of graphene is closely related to its content and number of layers. When preparing graphene absorbing materials, it is necessary to precisely control the content and number of graphene layers to achieve optimal absorbing performance and meet the diverse needs of absorbing materials in different fields. Through in-depth research on this correlation, it is expected to further optimize the performance of graphene absorbing materials and promote their widespread application in electronic devices, stealth technology, and other fields.
The above data is for reference only, and specific performance may vary due to production processes and product specifications.
