First-Principles Study on the Nanofriction Properties of Diamane: The Thinnest Diamond Film

Abstract

Diamane, the thinnest sp3-hybridized diamond film, has attracted great interest due to its excellent mechanical, electronic, and thermal properties inherited from both graphene and diamond. In this study, the friction properties of surface hydrogenated and fluorinated diamane (H- and F-diamane) are investigated with dispersion-corrected density functional theory (DFT) calculations for the first time. Our calculations show that the F-diamane exhibits approximately equal friction to graphene, despite the presence of morphological corrugation induced by sp3 hybridization. Comparative studies have found that the coefficient of friction of H-diamane is about twice that of F-diamane, although they have the same surface geometric folds. These results are attributed to the packed charge surface of F-diamane, which can not only effectively shield carbon interactions from two contacting films, but also provide strong electron–electron repulsive interaction, resulting in a large interlayer distance and a small wrinkle of potential energy at the interface. The interesting results obtained in this study have enriched our understanding of the tribological properties of diamane, and are the tribological basis for the design and application of diamane in nanodevices.

Degenerate p-Type and n-Type Doping of Diamane by Molecular Adsorption

“…The structures of H-diamane and F-diamane are shown in Figure a. The lattice constant of H-diamane is 2.529 Å, and it is 2.561 Å for F-diamane, which are similar to previous theoretical results (2.517–2.53 Å for H-diamane and 2.546–2.56 Å for F-diamane). − The interlayer separations for carbon layers in H-diamane and F-diamane are 2.045 and 2.055 Å, respectively, and the latter is close to the experimental result (2.05 Å for F-diamane) . The conduction band minimum (CBM) and valence band maximum (VBM) for H-diamane and F-diamane are plotted in Figure b.…”

Anisotropic Interlayer Force Field for Two-Dimensional Hydrogenated Carbon Materials and Their Heterostructures

“…Besides, the PBE + MBD-NL results provide the interlayer spacing of AAstacked bilayer H-diamane and graphene/graphane of 4.2 Å and 3.9 Å, respectively, which are in good agreement with the DFT reference data. 47,48 As the PBE + vdW-DF methods are known to overestimate the BEs (by ∼40%), 49 we adopted the PBE + MBD-NL approach in this work to calculate the DFT reference data. Notably, we found that the AC and AB′ stacking modes are most stable for parallel and antiparallel configurations of bilayer H-diamane, respectively.…”

Advancements in theoretical and experimental investigations on diamane materials

“…Surface chemical functionalization with unique species, such as H–, F–, and Cl– atoms and –OH groups, was deemed to be necessary for the 2D diamond structure to be thermodynamically stabilized. 24–31 In this case, both hydrogenation and fluorination of its surface were attempted experimentally 13,30 and the structures were labeled as diamane and F-diamane (FD) (two-side functionalized bilayer and few-layer graphene) discussed in literature, 32–34 respectively, to distinguish them from another diamane-like material called diamone, which is formed by the light atom passivation of one side of BLG. 35…”

“…Surface chemical functionalization with unique species, such as H-, F-, and Cl-atoms and -OH groups, was deemed to be necessary for the 2D diamond structure to be thermodynamically stabilized. [24][25][26][27][28][29][30][31] In this case, both hydrogenation and fluorination of its surface were attempted experimentally 13,30 and the structures were labeled as diamane and F-diamane (FD) (twoside functionalized bilayer and few-layer graphene) discussed in literature, [32][33][34] respectively, to distinguish them from another diamane-like material called diamone, which is formed by the light atom passivation of one side of BLG. 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.…”