I have a metal oxide nanoparticle covered by amorphous carbon. I want to dissolve the carbon layer, keeping the metal oxide nanoparticle but, unfortunately, I have no idea to conduct this.
Any suggestions for a method would be gratefully appreciated.
Dear Yusran,
dimethylformamide (DMF) isused to selectively remove amorphous carbon from carbon nanotubes. You might want to try it and I would suggest to use at least 100 mL of DMF per 1 g of product and to heat the solvent at 130 °C under.
Eventually, you might want to try solvents with a better affinity to both amorphous and nanostructured carbon, such as cyclic amides. In particular carbon-based materials show good solubility in N-methylpyrrolidone (NMP) or 1-cyclohexylpyrrolidone (CHP). You can also heat these solvents up to 180 °C without degradation. The cons are that these solvents have a high boiling point (202 °C for NMP and about 330 °C for CHP) and thus they might be difficult to remove after the purification stage.
In the article in attachment you might find other suggestions.
It would be difficult to dissolve, I would think - amorphous carbon coatings are often used precisely because of their inertness!
But. it probably depends (a) on the 'coating' (is it continuous or porous? Is it well adhered to the nanoparticle substrate?); and (b) what you mean by 'amorphous carbon', i.e. it could be soot, graphite-like, diamond-like or polymer-like carbon, and may or may not contain some quantity of hydrogen too.
It may be possible to remove the carbon using an oxygen plasma, if you have the facility to produce one?
If not, an article that may give some ideas (not sure how relevant this is to what you're doing) is here:
http://users.ox.ac.uk/~dplb0149/publication/pub93.pdf
Try this paper also.
http://cohesion.rice.edu/NaturalSciences/Smalley/emplibrary/ACF6A9.pdf
Dear Prof. Ross Birney and Prof. F. Caballero-Briones
thaks for the articles, I will surely study on it..
Dear Yusran,
dimethylformamide (DMF) isused to selectively remove amorphous carbon from carbon nanotubes. You might want to try it and I would suggest to use at least 100 mL of DMF per 1 g of product and to heat the solvent at 130 °C under.
Eventually, you might want to try solvents with a better affinity to both amorphous and nanostructured carbon, such as cyclic amides. In particular carbon-based materials show good solubility in N-methylpyrrolidone (NMP) or 1-cyclohexylpyrrolidone (CHP). You can also heat these solvents up to 180 °C without degradation. The cons are that these solvents have a high boiling point (202 °C for NMP and about 330 °C for CHP) and thus they might be difficult to remove after the purification stage.
In the article in attachment you might find other suggestions.
I would use ozone. It should oxidize the carbon rapidly and should not affect a metal oxide, unless there are higher valences for the metal. This is done dry. If the nano-particles tend to aggregate, they would have to be protected during or after the process. You might use perfluoro octanoate or perfluorooctane sulfonate salts. Both are commercially available and I think they are stable towards ozone.
Dear all,
Well actually, one my concerned also is dissolved the carbon layer while still keeping the metal oxide nanoparticle (Co3O4, higher valences metal) in both nanosized sclae and its oxidation state.
I would try CS2, if the layer is really C = carbon, and not some carbon-rich composition (oil?); I can not see how the analysis was made which let Yusran tell us the nanoparticles are covered by amorphous carbon, but if so, then CS2 should help.
I would not use any oxidizing method.
Dear Prof. Bernhard Wessling
Thanks for the suggestion. Let me state in briefly. I produced a metal nanopartilce inside of carbon layer from thermal treatment of precursor containing organic carbon. the end of this resulting a nano metal oxide covered by amorphous carbon. then my concerned in prefer the naked nano metal oxide...
understood, I am not sure whether CS2 can dissolve / remove this pyrolytic layer (it will not be pure carbon, but somehow also oxidized stuff, resembling coal). But I would try CS2 first, and I would run surface analysis like XPS or TOF-SIMS to determine what you have before and after treatment.
Good luck, let us know what was the result!
heat the carbon coated Metal oxide more than 600-800 degree in air atmosphere your amorphous carbon will decompose and will evaporate as CO2.so that you can obtain your pure metal oxide .Annealing temperature you can easily find using TG
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