The disappearance of the significant peak at 5.6 after freeze-drying your MXene (Ti3C2) liquid can be attributed to structural and compositional changes induced by the drying process. Freeze-drying often alters the interlayer spacing of MXenes, which can suppress or shift certain peaks. Additionally, particle agglomeration, the removal of intercalated water or solvents, and potential partial oxidation during the process may contribute to the appearance of new peaks and the loss of the original one. Further investigation using techniques such as TGA, SEM, or varying drying conditions (e.g., temperature and duration) could provide additional insights into these changes.

Best wishes!

Peak changes in XRD suggested the physical forms conversion of your sample due to drying. Sometimes, it can be due to chemical changes. You could apply Raman/IR spectroscopy to identify your sample/or mixture of multiple compounds.

It can be related to MXenes' oxidation or the distortion of the structure while drying. Try using Raman spectroscopy, as it is a much more sensitive method for MXenes analysis. Here are a few guidelines that might be helpful for MXenes analysis and quality evaluation:

Article Monitoring Ti3C2Tx MXene Degradation Pathways Using Raman Spectroscopy

Article Tip-Enhanced Raman Scattering Imaging of Single- to Few-Laye...

Simonas Ramanavičius Nikita Dubitskiy, if I used this powder to make a composite with another material, is it considered a Mxene composite? or can we not use this composite because Mxene is already destroyed?

If you use this powder to create a composite, it can still be considered a MXene composite if the MXene retains its characteristic structure and properties. However, MXenes are sensitive to processing conditions, and their properties can be significantly altered if they are destroyed or oxidized. If the MXene is no longer structurally intact or its properties are degraded, it may not function as intended, and referring to it as a MXene composite could be misleading. Whether it qualifies depends on whether the MXene’s properties are preserved in the composite.

Nikita Dubitskiy thank you

Wedad A. Alwesabi, my suggestion would be to check Raman spectra of MXenes if possible. You can check 406 cm-1 and 633 cm−1, 144 cm−1, bands which are associated with TiO2. It is likely that, in your case, MXenes degraded to TiO2.

Simonas Ramanavičius thank you