Beijing jiaotong university & sinomark fu chi & south university of science and technology, the late

With the rapid development of electronic technology and communication technology, absorbing materials of electromagnetic wave have attracted more and more attention. They are commonly used to reduce noise, reduce electromagnetic interference, and improve electromagnetic compatibility. At present, the types and applications of absorbing materials are more and more extensive. For example, high-speed railways, drones, satellites, radar and communications equipment all need absorbing materials to reduce their electromagnetic radiation and interference.

Figure 1 Development background of absorbing materials (picture from Baidu search)

The function of absorbing materials is to absorb electromagnetic waves in materials and dissipate them, so as to ensure no secondary pollution to electromagnetic waves, or to realize its "stealth effect" in military, which has greater advantages than electromagnetic shielding materials. The research status of the absorbing materials shows that the traditional absorbing materials can not achieve the requirements of "thin", "light", "wide" and "strong" at the same time. The development of new absorbing materials is also a great development opportunity for our country in the field of electromagnetic protection and stealth.

Recently，Beijing Jiaotong University, Southern University of Science and Technology and Zhongming Fuchi (Suzhou) Nano High-tech Materials Co., LTDResearchers toTi₃CNT_xBased on the studyTi₃CNT_x MXeneAbsorption properties of materials at 2-18GHz.Its research results are as follows“Two-Dimensional Nanosheets of Titanium Carbonitride Ti₃CNT_x MXene for Microwave Absorption in the X and Ku Bands”As the subject，Published in the latest issue of ACS Applied Nano Materials.

Figure 2. Development background of absorbing materials

MXene is a promising type of materials used in wave absorbing materials: the two-dimensional structure can significantly prolong the electromagnetic wave loss path, the rich surface functional groups make the material strong wetting ability, and provide a large number of dipole loss centers, in addition, MXene suitable conductive ability to ensure the impedance matching of the wave absorbing body. The general chemical formula of two-dimensional MXene and parent phase MAX can be expressed as：_{Mn+1XnTx and Mn+1AXn}，Where M represents transition metal elements, A represents group Ⅲ or Ⅳ elements, X can be C or/and N elements, n can currently be 1, 2 or 3,T_xIt's a functional group. Theoretical simulation results show that all MAX has corresponding MXene materials, and at present, more than a dozen kinds of MXene have been successfully synthesized in the experiment, such as:Ti₂C、Ti₃C₂、Ti₃CN、V₂C and Nb₂C。

Figure 3. Preparation of MXene [im, et al. Nat. Synth., 2022]

It is found that Ti₃CNT_x MXene particles can be prepared successfully by etching Ti₃AlCN MAX phase powders with HF acid.Ti₃CNT_xstill has a two-dimensional accordion structure similar to Ti₃C₂T_x MXene, and the surface of Ti₃C₂T_x is covered with -F, -OH and -O functional groups. In terms of absorbing performance, the lowest reflection loss value of Ti₃C₂T_x MXene can reach -41.36 dB, and the thickness is 1.94 mm. At the same time, the effective absorption bandwidth can reach 4.24GHz (13.76-18 GHz frequency range). This performance is higher than that of pure Ti₃C₂T_x MXene and pure graphene reported in most literatures. The high performance absorption of Ti₃C₂T_x MXene comes from:

1) Abundant surface functional groups of Ti₃CNT_x cause polarization loss;

2) The magnetism caused by N-Ti-F bond may cause a certain magnetic loss;

3) Interlayer reflection loss of Ti₃CNT_x;

4) At the macro level, the suitable distribution of Ti₃CNT_x stacked particles in paraffin wax caused the effective impedance matching between the absorber and electromagnetic wave.

For detailed study details, the reader is encouraged to refer to this document: 10.1021/acsanm.2c04062.

Figure 4. Ti₃CNT_x MXene microstructure

Figure5 .Ti₃CNT_x MXene Electromagnetic parameters and absorption performance at 2-18 GHz

Figure 6. Ti₃CNT_x MXene Absorption mechanism at 2-18 GHz

This research results for the first time reported Ti₃CNT_x MXene's electromagnetic parameters and absorbing properties at 2-18 GHz, further revealed the absorbing mechanism of MXene, and laid a foundation for expanding the application of MXene phase materials in the direction of electromagnetic stealth. This is also the third academic paper jointly published by Beijing Jiaotong University and Zhongming Fuchi (Suzhou) Nano High-tech Materials Co., Ltd. in the direction of high-temperature structures and two-dimensional metamaterials, and the second academic paper jointly published by the two parties and Southern University of Science and Technology. This is mainly due to the industry-university-research platform of cooperation between enterprises and universities, which adds impetus to enterprises' products and research and development.