How to clean the quartz tube used for CVD synthesis of graphene. The quartz tube was coated with copper that got deposited during graphene growth. Suggestion needed on chemical solvent which is good for removing both copper and oxides that got deposited inside the tube.
It seems for the attached photo, that you are using the central (clean) Zone for your growth. This wouldn't pose an issue on your growth condition, (please correct me if I'm wrong).
I would recommend using a new tube if it's really affecting the growth process, otherwise, some copper etchants that can be used are Ammonium Persulphate which generally requires longer time to remove the copper. Another option with a faster etching rate (few minutes) is Ferric Chloride. Just place a small amount of Ferric Chloride and scrub with long stick with a fabric at the end.
You can rinse the with the aquous Fe3(NO3) using syringe with regualar intervals followd by DI water ..........
It may be rather difficult ─ if not impossible ─ to completely clean the quartz tube from the copper contamination if the tube was taken to high temperature, due to possible high temperature diffusion of copper beneath the surface. Nevertheless, you may try cleaning the tube from the copper residual layer with strong copper etchants. Quite a few options can be tried: (i) conc. nitric acid (preferably) with added hydrogen peroxide; (ii) aqueous ammonium hydroxide, ammonium persulphate or ammonium carbonate, with added hydrogen peroxide and/or potassium hydroxide; (iii) ammonium persulphate (~40 wt %) acidulated with conc. sulphuric acid; (iv) concentrated sulphuric acid or either aerated or oxygenated diluted sulphuric acid (~10% w/w); (v) solution (~1:2) of hydrogen peroxide (~20 w/v) in sulphuric acid (~15 % w/w); (vi) chromic acid (~10 % w/w), (vii) mixture (~1:2) of chromic acid with sulphuric acid (both ~10 % w/w). To further enhance the etching (cleaning) capability the aforementioned solutions you can prepare aqueous solutions with aerated or (preferably) with oxygenated water. In case you also have a copper(II) oxide layer, you may consider its previously cleaning with hot diluted acetic acid.
Heat the tube in air at > 1000 deg C to remove any organic/residual contaminants. Then clean the tube using 1 M FeCl3 solution in concentrated HCl. You can also try using the strong Cu etchants mentioned by Carlos in his reply above.
Hi
We basically etch away the inner quartz layer by cleaning it with diluted HF/water solution (1/20) or best way is paper a bath tub fill it with 1/50 (HF/water) and put the tubes for overnight. After bathing open air anneal of the tubes at 1000C for 1 or 2 hrs
Hi, i have a quite same problem
but it s not copper that is attached to the inner face of the quartz tube, it s concentrated KOH, i use it to activate carbon at 750° and it sticked inside, and now we need to fabricate graphene and the tube needs to be cleaned from attached solid KOH, any help please ?
PS : i used DI water (since koh is soluble in water), 2M HCl, Acetone, tried to burn it at 700 again, nothing of this worked ....
what can i do to remove the solid KOH residue from the quartz tube ?
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