Ultrathin MXene Preparation with Repeated Freeze-Thaw Method

 MXene, as a member of a unique family of two-dimensional nanomaterials , combines the advantages of superior electrical conductivity, large specific surface area, and hydrophilicity, and has been widely used in lithium-ion batteries, electrochemical storage systems, electromagnetic interference shielding, and electrical Catalyst, photothermal conversion and other fields.People usually pay close attention to the function of MXene , but ignore the lower yield. The research to improve the productivity of MXene can avoid unnecessary waste and has great practical significance for large-scale production.

Achievements

     Recently, Fudan University, Professor Wu Peiyi well-known in the international journal Advanced Functional Materials published entitled " A Facile, High-Yield, and Freeze-Thaw-and-Assisted Approach to Fabricate MXene with Plentiful Its Wrinkles and the Application in the On-Chip Micro-Supercapacitors " Thesis innovatively proposes to use the repeated freeze-thaw method to open the MXene sheet with the force of freezing expansion of ice crystals. After several cycles, MXene nanosheets with a special wrinkle structure were prepared in a high yield of 39% without ultrasound. After ultrasound treatment, the MXene yield reached a record-breaking 81.4%. Microcapacitors made from this unique MXene nanosheet also exhibit excellent capacitance performance.

FIG . 1 ( A ) the FAT Preparation of Ti _{. 3} C ₂ schematic diagram; ( B ) of Ti _{. 3} AlC ₂is SEM image; ( C ) Multilayer - of Ti _{. 3} C ₂ , ( E, F ) have a significant surface wrinkles FAT- ti _{. 3} C ₂ ; ( D ) m-ti _{. 3} C ₂ after freeze sem image; ( G, H ) the HRTEMFIG; ( I ) the XRD FIG.  

Figure 3 ( a ) UV - visible absorption spectrum and ( b ) yield of FAT-MXenedispersion with different number of cycles ; ( c ) and ( d ) are ( 002 ) peak angle values of FAT-MXene with different number of cycles .

FIG . 4 ( A ) MXene a TEM of FIG. ( B ) or absence FAT circulating m-MXenecomparison chart; ( C ) FAT prepared by FAT-MXene comparison with the reported literature.

FIG . 5 ( A ) ultrasound -MXene with FAT-MXene comparison of FIG film ( BC ) of the flexible FAT-MXene film photos; ( DF ) FAT-MXene film the XRD , IV curves and the tensile curves; ( GI ) ultrasound -MXene and ( JL ) the FAT-MXene film SEMFIG.

Figure 6 ( ac ) Preparation of MSC ; ( dg ) Photographs of each process, scale is 15 mm.

Fig. 7 ( ab ) Top view of SEM of m-MSC ; ( c ) Test chart of MXene electrode film; ( d ) CV curves at different scanning speeds ; ( e ) Charge of m-MSC ofdifferent thickness at constant current and different current density Discharge(GCD) diagram; ( f ) CV curve at a scan rate of 20 mV s ⁻¹ ; ( g ) Volume capacitance of m-MSCs of different thicknesses ; ( h ) ) m-MSCs of different thicknesses at different current densities the volumetric capacitance; ( I ) the FAT-MXene the MSCComparison of volumetric energy and power density with other reported MSCs .

in conclusion

The MXene sheet was opened by proposing a simple, effective and gentle repeated freeze-thaw method . After 4 cycles, the size of Fat-MXene nanosheetswith special wrinkles is larger, and the yield can be as high as 39% . Combined with sonication, although the size has been reduced, the yield has been further increased to 81.4% . Fat-MXene assembled miniature capacitors have a surface capacitance of up to 23.6 mF cm ^–2 and a bulk capacitance of 591 mF cm ^–3 .Excellent electrochemical performance and thus prove the strategy of high quality fat of mesenchymal stem cells. This research opens up a new method to improve the yield of MXene , which is beneficial to further expand the application of MXene . 

Original link:

https://doi.org/10.1002/adfm.201910048

Source: MXene Academic