In our humble opinion:
- One layer is true graphene (the real deal);
- 2 to 10 Layers is multilayer graphene;
- More than 10 layers is actually graphite.
But, why is multilayer graphene not as good as people think?
If you can imagine a “small” deck of cards, say up to ten cards, you bond the upper and lower cards, but as you bend the deck, the intermediate layers (i.e. individual cards) can easily separate due to the weak Van der Waals forces, resulting in weakness in the matrix. In contrast, if you take one-layer sheet of graphene, while the graphene layer can still bend, the matrix however remains stable.
In order to attach graphene to a matrix (almost any sort of matrix), you simply need to add defects/active groups on the graphene to create bonding sites. In this regard, the words doped/doping, as in doped graphene or graphene doping, commonly refer to adapting the graphene structure to make a binding on either the plane or edges of the graphene. The binding can be in forms of functional groups or defects, including, but not limited to, oxygen functional groups, which can act as active sites for interaction with many different gas molecules or chemicals.