Just I want to prepare group of polycyclic aromatic hydrocarbons from graphene or graphene oxide. Are there any ways to do so other than ultrasonication?
Well it is difficult to control the chemistry of products, specially if you want to achieve equivalent molecular weight products. breaking down mostly leads to complete degradation of some parts, and some are partial rings. also look for the attached link. I hope this can be slightly helpful for you.
Forgive me, but I thought the question posed was for a method that did not involve ultrasonication. If so, perhaps extensive ball-milling might be an alternative?