Did you at least read a title of the link you posted? I'll copy it for you:

Making Magnetic Graphene Oxide - Fe3O4 magnetic nano particle composite system

Fe3O4 is not a graphene! It is black iron oxide. There also could not be any "graphene solution" or "graphene oxide solution" because both graphene and graphene oxide is insoluble in water. Anything that combined with black iron oxide(Fe3O4) will stick to magnets. Whatever - wooden sawdust, paper pulp, charcoal powder, anything fine balck iron oxide particles could stick to. You could make absolutely anything "magnetic" just using fine black iron oxide powder in some binder as paint. And it is used so a lot. It even have its own color designation - Black 4330. But all that have absolutly nothing to do with graphene. Grafene itself is not ferromagnetic and can't stick to magnets, Fe3O4 is.

You are incredibly stupid or amasingly insolent in pushing bullshit here!

Did you at least read a title of the link you posted? I'll copy it for you:

Making Magnetic Graphene Oxide - Fe3O4 magnetic nano particle composite system

Fe3O4 is not a graphene! It is black iron oxide. There also could not be any "graphene solution" or "graphene oxide solution" because both graphene and graphene oxide is insoluble in water. Anything that combined with black iron oxide(Fe3O4) will stick to magnets. Whatever - wooden sawdust, paper pulp, charcoal powder, anything fine balck iron oxide particles could stick to. You could make absolutely anything "magnetic" just using fine black iron oxide powder in some binder as paint. And it is used so a lot. It even have its own color designation - Black 4330. But all that have absolutly nothing to do with graphene. Grafene itself is not ferromagnetic, Fe3O4 is.

You are incredibly stupid or amasingly insolent in pushing bullshit here!