Two-way frozen long-range ordered MXene aerogel

The rapid development of wireless communication technologies and applications, as well as the trend towards miniaturization and the popularity of mobile wireless electronic devices, have led to increasingly complex electromagnetic environments. To prevent electromagnetic pollution, the demand for flexible, lightweight electromagnetic shielding materials in different frequency ranges is also increasing. However, high-performance electromagnetic shielding materials are still a huge challenge. Due to the internal multiple scattering and the interaction of local currents on the upper wall or hole with the electromagnetic wave, the macroporous structure is an effective way to improve the electromagnetic wave absorption capacity. 2D transition metal carbides and carbonitrides ( MXenes ) have proven to be excellent shielding materials. MXeneflakes have high electrical conductivity and their surfaces are -OH , -O and -Fgroups, giving them hydrophilicity and the possibility of solution processing. Many encouraging developments have also been made.

Achievements

Recently, Drexel University ‘s Yury Gogotsi professor well-known in the International Journal of Advanced Optical Materials published entitled"Anisotropic MXene Aerogels with a Mechanically Tunable Ratio of Electromagnetic Wave Reflection to Absorption" papers. A tunable long-range ordered bionic three-dimensional porous aerogel structure composed of MXene was reported . The two-way freezing method is ideal for making MXene colloidal solution into a sturdy, compressible, lightweight aerogel oriented assembly structure, which can obtain excellent electromagnetic shielding performance and adjustable reflection absorption performance. The electromagnetic shielding effectiveness of the three types of MXene aerogels (Ti ₃ C ₂ T _x , Ti ₂ CT _x , Ti ₃CNT _x ) reached 70.5 , 69.2, and54.1 dB with a compression thickness of only 1mm and a density of 11.0 mg cm ^{− 3} . The highest specific performance is 8818.2 dB cm ³ g ^{− 1} , which is one of the best reported values for electromagnetic interference shielding materials .

Figure 1 Schematic diagram of MXene aerogel preparation .

Figure 2 Structure of MXene aerogel .

Figure 3 Mechanical properties of MXene aerogel .

Figure 4 Shielding effectiveness of MXene aerogel .

Figure 5 Shielding mechanism of MXene aerogel .

in conclusion

In short, a series of long-range ordered layered structures of MXene ( Ti ₃ C ₂T _x , Ti ₂ CT _x, and Ti ₃ CNT _{x) were} prepared by two-way freezing method . Compared to traditional random aerogels, after 20 compressions After the performance test, the MXene aerogel maintained a stress of 84.5 % and a stable electrical conductivity. At a thickness of 1 mm , the Ti ₃ C ₂ T _x , Ti ₂ CT _x, and Ti ₃CNT _x aerogels were at 8.2-12.4 GHz . The average EMI SE of the frequency is70.5 , 69.2And 54.1 dB . The highest specific efficiency of Ti ₂ CT _x aerogel is8818.2 dB cm ³ g ⁻¹ , which is one of the best reported materials for electromagnetic interference shielding . This low specific gravity, high compressibility and high EMI shielding performance of MXene aerogel has great potential in the design of portable and flexible electronic devices.

Original link:

https://onlinelibrary.wiley.com/doi/10.1002/adom.201900267

Source: MXene Academic