Once the MAX phase is synthesized how can one store the obtained powders? Any ideas on the storage? Also if one has synthesized the MXenes how to store the obtained MXenes?
I need some clear information on storing these products like storing in vials etc...
You must classify your question and select the right forums. "Storage" is too generic. Today, storage may mean data storage more than anything else.
C.P. Ravikumar
Dear Sir, I was mentioning storage as storing of powders in bottles or vials.
For MAX phase, you don't need to do anything special to store them. MAX phases won't oxidize or degrade at room temperature in oxygen. In fact, MAX phases are renown for their oxidation resistance. Feel free to store them on your bench or in a drawer like any normal ceramic powder.
MXenes are more sensitive to oxidation, but there are a few factors to consider. Multilayer powder (after etching, before delamination) is more stable. With these, if you store them in Ar away from light, they will last for many months without significant degradation. I don't recommend completely drying the multilayer powder because it is them hard to delaminate them in the future.
For delaminated MXenes, you should try to use them as quickly as possible. Some MXenes (Mo-based) will last a very long time without significant degradation, others (Like Ti2CTx) have a shorter shelf life (weeks at best). Apart from this, there are a few factors that will increase your MXene lifetime that you can control:
@ Christopher Shuck
Thank you for your answer sir. Will follow the steps you mentioned.
Dear Christopher Shuck , how about putting MXene powders into non-polar liquid and store as a highly-concentrated suspension?
Alexander Khort, it may be possible to store MXene in a similar way. You won't have a stable dispersion of the MXene in solution, instead, all of MXene would agglomerate and settle onto the bottom of your vial. Moreover, you would run into impurity problems. With non-polar liquids, they shouldn't intercalate (well) between MXene sheets, but there may be some.
In general, with standard MXene, you won't run into rapid oxidation problems if you use the MXene in a timely manner and store it as I mentioned above.
Thanks Dr Christopher Shuck for the invaluable comments regarding the storage. However, oxidation is occurred during the synthesis process even if you follow all standard instructions. In fact, the synthesis process of high-quality MXenes is difficult. I appreciate if you talk some about the key points regarding the synthesis and its important strategies. Thanks in advance!
Some MAX phases get oxidized with time, it might not be visible with XRD, but it has a huge effect on the MXene synthesis and the quality and yield of the MXene produced, the best way to avoid that is to store them under vacuum or in an inert atmosphere such as a glove box.
Regarding MXene storage, powders can be also stored in a vacuum or inert atmosphere (after making sure that all the water has evaporated, best to do overnight annealing at about 150-200C in a vacuum or Ar oven).
Regarding colloidal solutions: here are some tips:
1. make sure your solution is concentrated as much as possible above 4 mg/ml should be ok, usually, the higher the flakes to water ratio would help to prevent oxidation.
2. Deariate your colloidal solution with Ar or N2 for about an hour.
3. What I use is crimped glass vials which I crimp them inside a glove box then use a syringe to insert the colloidal solution inside them, then wrap with Al foil and store in a fridge or freezer, for most of the MXene this should keep them stable for at least a week.
Hope this helps.
Massoud Malaki , if you follow the protocols in this article: Article Modified MAX Phase Synthesis for Environmentally Stable and ...
you will have very stable and high quality MXene. Very broadly speaking, the higher HF content you use, the more defective your MXenes will be:Article Atomic Defects in Monolayer Titanium Carbide (Ti3C2Tx) MXene
Generally, what this means. If you produce your MAX phase to be high quality (using the high Al approach above). Then use a more up to date synthesis method (such as the HF/HCl approach described here: Article Scalable Synthesis of Ti3C2Tx MXene
), you can produce MXenes with larger flake sizes, higher conductivity, and better stability. Of course, MXenes other than Ti3C2 follow the same principles, but we haven't optimized them nearly as much yet.
How long can the MXene etched with hydrofluoric acid be stored at room temperature?
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