Hexagonal boron nitride (h-BN), a layered material similar to graphite, is a promising dielectric. Monolayer h-BN, so-called "white graphene", has been isolated from bulk BN and could be useful as a complementary two-dimensional dielectric substrate for graphene electronics. Here we report the large area synthesis of h-BN films consisting of two to five atomic layers, using chemical vapor deposition. These atomic films show a large optical energy band gap of 5.5 eV and are highly transparent over a broad wavelength range. The mechanical properties of the h-BN films, measured by nanoindentation, show 2D elastic modulus in the range of 200-500 N/m, which is corroborated by corresponding theoretical calculations.

The chemical inertness of the defect-free basal plane confers environmental stability to MoS single layers, but it also limits their chemical versatility and catalytic activity. The stability of pristine MoS basal plane against oxidation under ambient conditions is a widely accepted assumption however, here we report single-atom-level structural investigations that reveal that oxygen atoms spontaneously incorporate into the basal plane of MoS single layers during ambient exposure. The use of scanning tunnelling microscopy reveals a slow oxygen-substitution reaction, during which individual sulfur atoms are replaced one by one by oxygen, giving rise to solid-solution-type 2D MoSO crystals. Oxygen substitution sites present all over the basal plane act as single-atom reaction centres, substantially increasing the catalytic activity of the entire MoS basal plane for the electrochemical H evolution reaction.

Engineering of the optical, electronic, and magnetic properties of hexagonal boron nitride (h-BN) nanomaterials via oxygen doping and functionalization has been envisaged in theory. However, it is still unclear as to what extent these properties can be altered using such methodology because of the lack of significant experimental progress and systematic theoretical investigations. Therefore, here, comprehensive theoretical predictions verified by solid experimental confirmations are provided, which unambiguously answer this long-standing question. Narrowing of the optical bandgap in h-BN nanosheets (from ≈5.5 eV down to 2.1 eV) and the appearance of paramagnetism and photoluminescence (of both Stokes and anti-Stokes types) in them after oxygen doping and functionalization are discussed. These results are highly valuable for further advances in semiconducting nanoscale electronics, optoelectronics, and spintronics.

We consider a new C 2 H nanostructure based on bilayer graphene transformed under the covalent bond of hydrogen atoms adsorbed on its external surface, as well as compounds of carbon atoms located opposite each other in neighboring layers. They constitute a "film" of the 111 diamond with a thickness of less than 1 nm, which is called diamane. The energy characteristics and electron spectra of diamane, graphene, and diamond are calculated using the density functional theory and are compared with each other. The effective Young's moduli and destruction thresholds of diamane and graphene membranes are determined by the molecular dynamics method. It is shown that C 2 H diamane is more stable than CH graphane, its dielectric "gap" is narrower than the band gap of bulk diamond (by 0.8 eV) and graphane (by 0.3 eV), and is harder and more brittle than the latter.