Graphene spray and ...

there are dozens

try a search for "2D heterostructures" and see what pops up

Deekay, this may help " Beyond the study of graphene in the past decade, the discovery of other two-dimensional (2D) materials, like hexagonal-Boron Nitride (h-BN) and Molybdenum Disulfide (MoS2), have opened new doors in materials science and condensed matter physics." From OIST.

 Graphene is the basic structural element of common carbon based materials, including graphite, charcoal, carbon nanotubes and fullerenes(other molecules of carbon).
It is so strong because the electrical attraction between carbon atoms is very strong and that is the source of strength for both graphene and diamond.

Graphene is basically 2-dimensional graphite. Graphite is soft and slippery because it’s in layers of 2-dimensional carbon atom "sheets" weakly bonded to other sheets of similar carbon.

Graphene is therefore a single "sheet" of carbon atoms arranged in hexagons. The carbon-carbon bonds in the 2-D section of graphite (and thus also graphene) are stronger bonds than carbon atom bonds in diamond, hence the "super" properties of graphene.

Graphene is right now rather difficult to make - it was literally discovered by putting a piece of scotch tape on graphite, carefully pullling up the tape leaving a single layer of graphene.

https://en.wikipedia.org/wiki/Graphene_production_techniques <--- This should answer questions as to how one would apply Graphene to a speaker driver. It $ur€ won't b€ ¢heap....

"Graphene is right now rather difficult to make - it was literally discovered by putting a piece of scotch tape on graphite, carefully pullling up the tape leaving a single layer of graphene."

Huh? Rather difficult? Sounds pretty easy to me. If it was difficult it wouldn't have been discovered accidentally. Tons of DIY videos on YouTube for the avid tweaker.