Dear all,
Intro:
After a hell of a lot of work, we learned a great deal of info, and finally finish to set up our own Ge NPs colloidal synthesis, which unluckily for me requires the amine as solvent/capping agent.
So now i can make my germanium nanoparticle easily, but they come with this nasty amine around that basically quenches my optical properties and act at the same time as an insulator, so erasing my electrical properties. So to make it short i can make them but with all this amine-crap around i can't do a thing.
I want to get rid of the amine, and ideally end-up with hydrogenated surfaces to be able to do further surface chemistry and functionalize them. I'm trying different approaches, one of which would be chemical etching. I have a chemistry background and i'm trained to use acid, but nor me nor my collegues/supervisors have ever performed such an experiment. so far I've picked the couple HNO3/HF for the etching
Question:
Once i perform the etching, the resulting hydrogenated surfaces are going to be very unstable, hydrophobic, prone to oxidation, and stuff. i have already the solution with the replacement capping agents standing by. how do i get the nanoparticle out of the acid and into the capping agent solution, without oxidizing them?
Note:
The nanoparticle are free floating, there is no substrate or bulk piece i can take out and rinse.
Dear Bruno Pescara,
My colleague, who work in the field of molecular beam epitaxy using the cleaning procedure described in the work: 10.1016/0039-6028(94)91117-7 (attached), but they use a different concentrations of HF and H2O2, you can find them in the comments. The cleaning includes germanium oxidation and oxide removing, so I think this is quite a gentle etching.
In addition, I have found couple of work there described a cleaning, surface passivation, functionalization of Ge(100) (attached). Hope they will be useful for you.
Dear Evgeniy Anatoljevich Chusovitin ,
Thanks for the suggestion.
I'm aware of oxide formation/removal with different oxidizing and etching methods.
Unluckily as i mentioned in the question, my NPs are free floating(dispersed in a colloidal solution), therefore i cannot "dip" or "remove".
In the very same way i cannot filter, since my NPs are smaller than any pore size of the filter papers.
The only solution that works right now would be centrifugation, but i have to prevent oxygen exposure, so first i'll have to find HF resistant vials (no big problem i think), then a glove-box where they let me make a reaction and an acid bath (which is surely not going happen in the glove-boxes of my lab, my supervisor would kill me), and the centrifuge should have to be in the very same glove-box.
I could split the reaction and perform it outside the glove-box (with several problem associated) and load the NPs in the glove-box but i would still to have to do the etching and centrifuge in there, and as a rule most of the glove-boxes responsible don't like solvents (let alone acids) in glove-boxes, and surely they most often don't waste so much space in a glove-box to install there a centrifuge.
So i'm asking if somebody with experience in the field of chemical etching of NP came up with an idea better than mine
Thanks again
Bruno
Instead of removing + replacing them with the equivalent of an etching agent, why not derivatize the amines directly? This article shows the concept. A deeper literation search might reveal a specific organic chemistry reaction that works for the system that you have.
Article Functional PEG–PAMAM-Tetraphosphonate Capped NaLnF4 Nanopart...
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