Construction of hydrangea-like core–shell SiO ₂@Ti ₃C ₂T _x @CoNi microspheres for tunable electromagnetic wave absorbers

Abstract

Ti3C2TxMXene shows great potentials in the application as microwave absorbers due to its high attenuation ability. However, excessively high permittivity and self-stacking are the main obstacles that constrain its wide range of applications. To tackle these 2 problems, herein, the microspheres of SiO2@Ti3C2Tx@CoNi with the hydrangea-like core-shell structure were designed and prepared by a combinatorial electrostatic assembly and hydrothermal reaction method. These microspheres are constructed by an outside layers of CoNi nanosheets and intermediate Ti3C2TxMXene nanosheets wraping on the core of modified SiO2, engendering both homogenous and heterogeneous interfaces. Such trilayer SiO2@Ti3C2Tx@CoNi microspheres are "magnetic micro size supercapacitors" that can not only induce dielectric loss and magnetic loss but also provide multilayer interfaces to enhance the interfacial polarization. The optimized impedance matching and core-shell structure could boost the reflection loss by electromagnetic synergy. The synthesized SiO2@Ti3C2Tx@CoNi microspheres demonstrate outstanding microwave absorption performance benefited from these advantages. The obtained reflection loss value was -63.95 dB at an ultra-thin thickness of 1.2 mm, corresponding to an effective absorption bandwidth of 4.56 GHz. This work demonstrates the trilayer core-shell structure designing strategy is highly efficient for tuning the MA performance of MXene-based microspheres.

Construction of Hollow Carbon Nanofibers with Graphene Nanorods as Nano-Antennas for Lower-Frequency Microwave Absorption

“…The addition of ZIF-67 particles leads to the formation of a highly conductive phase of Co and graphene layers, which also enhances the attenuation ability of samples. The heterogeneous interfaces among amorphous carbon, Co particles, and graphene layers can increase the interfacial polarization loss in samples. , Apart from that, the defects of carbon phases can enhance the dipole polarization loss. , Most importantly, the graphene nanorods as nano-antennas can guide the EM wave into materials, leading to the enhancement of impedance match conditions. This unique structure can provide new insight into the design of EM wave absorbers for lower frequency.…”

“…The heterogeneous interfaces among amorphous carbon, Co particles, and graphene layers can increase the interfacial polarization loss in samples. 54,55 Apart from that, the defects of carbon phases can enhance the dipole polarization loss. 56,57 Most importantly, the graphene nanorods as nano-antennas can guide the EM wave into materials, leading to the enhancement of impedance match conditions.…”

Synthesis of nitrogen-doped graphene aerogels modified by magnetic Fe3O4/Fe/C frameworks as excellent dual-band electromagnetic absorbers

“…4, both S2 and S3 exhibit typical ferromagnetic hysteresis loops. 37,38 Furthermore, the values of saturation magnetization ( M s ) for S2 and S3 are 105.2 emu g −1 and 10.4 emu g −1 , respectively. Therefore, compared with S2 (Fe 3 O 4 /Fe/C composite), the magnetism of the prepared composite aerogel (S3) is significantly reduced due to the complexation with the non-magnetic component of NRGO.…”

“…In addition, the ferromagnetic hysteresis characteristics of the obtained composite aerogel will help dissipate electromagnetic energy under the alternating electromagnetic field. 37,38…”

Synthesis of high-entropy MXenes with high-efficiency electromagnetic wave absorption

“…M n+1 X n T x compounds (shortly refereed as MXene, where M denotes an early transition metal, X is carbon and/or nitrogen, T x represents surface terminations, such as -O, -F, -OH, and -Cl, and n usually varies from 1 to 3) are a large family of two-dimensional (2D) transition metal carbides and nitrides [8,9]. Generally, MXenes are obtained from their precursors, M n+1 AX n ternary compounds (MAX phases), by selective etching of the A layers, which usually stands for an A-group element [10].…”