“…35 The synthesis routes for diamane can be roughly classified into two major categories, where one route is surface functionalization-induced interlayer carbon atoms bonding in bilayer or multilayer graphene under atmosphere pressure, while the other route is to convert bilayer or multilayer graphene to diamane directly by applying high pressure, similar to the transformation of graphite to diamond. The former route generates functionalized diamane, which is stable with heteroatoms on its surface, were the products may be diamondol (when the topmost surface is covered with -OH groups), 10 diamanoid 19,36 (crystalline sp 3 -bonded 2D carbon materials either similar to diamane but composed of more than two layers or with only one outer hydrogenated (or fluorinated) layer regardless of the number of layers) or diamondene 14 (a mixture, diamondized by hydroxyl groups and hydrogens) depending on the surface functional atoms and the layers of graphene precursor. In contrast, the latter route can usually be used to obtain clean diamane (CD) with carbon atoms only.…”