I had synthesized MoS2 nanosheets by the help of liquid phase exfoliation using probe sonication. The solvent used was a 50/50(vol%) of IPA/DI water mixture. Pre-processing of the sample was carried out bath sonication, followed by probe sonication. The sample was then centrifuged to remove un-exfoliated bulk material and the supernatant which contains the nanosheets was collected for further processing.
When characterized using a spectrophotometer with the IPA/DI water co-solvent as refernce, the absorption peaks of MoS2 (~612nm and ~674nm) weren't observed even though the suspended particles were clearly visible in the solvent.
What could be the reason? Also what could I do differently?
I have attached the absorption spectrum and the protocol followed as reference.
TIA.
Hi Mehul,
It may sound very obvious and pardon me if you have already considered it. However, your data seems to be missing a baseline. I'd suggest that you repeat the measurements with a baseline corrected for a blank solvent, which in your case would be 50/50(vol%) of IPA/DI.
You can then compare any changes in spectrum with respect to the baseline and proceed further. Another problem I can suspect is the nature of cuvette you're using. Make sure it does not interfere or absorb with your measurements as in my experience PS cuvettes can sometimes cause problems.
I hope this solves your problem.
Hey Aditya Chauhan
Im sorry I think I forgot to mention that I had used the same co-solvent as a baseline.
Thanks a lot for your input, will check up on the data and the cuvette again.
Hey Jonathan Belew ,
I tried out your suggestion, and it seemed to work. Thanks a lot.
The papers i am referring to seem to have obtained peaks for the supernatant after centrifuge whereas i happened to get the peaks only once i resuspended the sediment into the solvent. What could be a possible reason?
TIA.
My guess would be that their supernatant was a higher concentration to start with for whatever reason. They may have just had a more sensitive instrument. The quality of the starting product as well as the solvents involved would be my guesses at the concentration if that happened to be the issue. I assume you used the same RPMs for the centrifuge?
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