[mapt]

A square meter of a single-atom-thick layer of graphene isn't very relevant. Expect the final product to have a volumetric density in the neighborhood of graphite or diamond.

[sliverstorm]

Probably closer to graphite, as to my knowledge graphite is literally just layers of graphene.

[Retric]

You need to separate each layer with an insulator to be effective, otherwise you could just use graphite.