I tried to use a method from my references to synthesize a core shell QDs, and I followed its methods for synthesis.
However, when I prepared the Cd and Zn precursor, they degraded (the solution turn brown) at high temperature. Does anyone know what happened to this?
http://pubs.acs.org/doi/abs/10.1021/cm801201x
In the procedure it is indicated N2 Injection after degassing at negative pressure of 100 mTorr.. thus, remaining oxygen is clearly deleterious...
Probably what you got, is a complex rather than a nanoparticle. This should be due to the use of improper atmosphere as indicated above. Try to degas your solution by bubbling N2 through it for at least 20 min then try to keep a nitrogen blanket/inject N2 while you are running the reaction. If possible do the reaction inside the golvebox (it will work for sure) and good luck.
Thank everybody. I did it for degassed at 150 oC for 30 min, then filled with N2 to 310 oC, so my precursor may degrade because oxygen or H2O particles involve with? (my holder is not glovebox)
Then does anybody knows how many oxygen or H2O will result in my precursor degrade?
( why some reaction don't need to in the air-free condition? )
Also, why oxygen or H2O can cause my precursor degrade?
( what happened to them? )
thanks a lot.
Your solvents, salts etc must be dry. The degassing must be done at vaccum (100 mTorr), the injection of N2 I understood that is just before degassing, not at 310oC. (there are not H2O particles, by the way). About why the precursor degrades with oxygen/water, I suggest you to get a chemistry textbook and review the properties of the specific precursors you are using.
Dear Caballero-Briones
Do you mean I should bubbling N2 to my solvent, then degas at vacuum (at least 100 mTorr) for the proper time to make sure there are no oxygen and H2O, then I can heat my precursor to higher temperature with N2?
And thank you your rectify (Should I say H2O molecule?)
And why water molecule influence my reaction, maybe because itself has oxygen element and oxygen element to my precursor is improper.
(Also H2O has other influence to reaction by this reference mention)
Thank you very much.
http://pubs.acs.org/doi/pdfplus/10.1021/cr100449n
Try to dry your solvent using standard methods. H2O may cause hydrolysis to your precursor and thus you may get poly-oxospecies.
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