Ti3C2Tx MXene nano-sheet / metal-organic frame composite

I. Overview of the article. 




The high performance absorber which enriches the three-dimensional structure of interface lamination can obviously improve the performance of electromagnetic wave absorption. At the same time, the etching of binding and splitting components has a positive effect on the microwave absorption (MA) performance of excellent absorption bandwidth. In this paper, accordion state MXene/Co-ZIF/Ni-ZIF composites were synthesized by using MXene and metal-organic frames (Co-MOF and Ni-MOF), and then pyrolyzed in H2/Ar mixed atmosphere (Co-MOF and Ni-MOF were named Co-ZIF and Ni-ZIF, respectively). 


Second, guided reading of picture and text. 






Figure 1. 
Schematic diagram of manufacturing process for MXene/Co-CZIF and MXene/Ni-CZIF. 



Figure 2. 
XRD mode (a), Raman spectrum (b), N2 adsorption-desorption isotherm (c) and pore size distribution of MXene@Co-CZIF and MXene@Ni-CZIF (d). 

In figure an above, the data show that Ni-CZIF (blue line) is successfully synthesized, and the pattern shows strong diffraction peaks at 44.2,51.8 and 76.2 °, indicating that Ni-CZIF is successfully decorated on MXene. In addition, in figure b, using Raman spectroscopy to obtain information, there are two obvious D peaks (1350cm-1) and G peaks (1580cm-1), which are related to the defects in the carbon lattice and the in-plane tensile vibration of sp2 hybrids. 



Figure 3. 
The XPS patterns of elements and components of all samples were detected. 

There are three obvious peaks in figure a, which indicate the existence of C, O and Co elements. In figure d, due to the weak oxidation of nickel, the other spin orbit coupling peaks are 859.5 and 870.5eV, respectively. It can be concluded that Co-CZIF and Ni-CZIF are successfully modified on the MXene matrix. 



Figure 4. 
SEM images of all samples. 

Figure a, b:MXene, show the morphology of MXene, indicating the effective exfoliation of the maximum phase, therefore, Co-CZIF and Ni-CZIF nanoparticles can be easily modified on the surface and interior of MXene. Figure c, d Ni-CZIF show a typical and uniform polyhedral structure (average size 400nm) on the surface and interior of MXene. EfMXene@Ni-CZIF, after electrostatic self-assembly, spherical layered nanoparticles were successfully deposited on the surface and interior of MXene. 



Figure 5. 
Schematic diagram of the possible MA mechanism of MXene@Co-CZIF and MXene@Ni-CZIF. 

The transfer of the MXene film from the fully covered surface to the target substrate results in a floating MXene film with partial area coverage. Then, a few drops of ethyl acetate were added to the uncovered area, and the self-assembly process was resumed with a new MXene sheet. In further iterations, no further hydrochloric acid was added to minimize the aggregation of MXene sheets. 

III. Summary of the full text. 

MXene/Co-CZIF50% composites show good absorption properties. In 7.36GHz, the best RL value is-60.09dB and the broadened absorption bandwidth is 9.3GHz (RL <-10dB).Under 5.12GHz, the RL value of MXene/Ni-CZIF5 measures the good performance of high-64.11dB and has an effective response bandwidth higher than that of foreign 4.56GHz (RL <-10dB). In addition, a unique accordion structure, magneto-dielectric coordination, multi-interface scattering and reflection, and dipole polarization improve MA performance. This paper provides a new idea for the synthesis of high performance microwave absorbing materials using MOFs and MXene matrices. 

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