Two-layer freestanding heterostructure consisting of VS2 monolayer and graphene was investigated by means of density functional theory computations as a promising anode material for lithium-ion batteries (LIB). We have investigated lithium atoms’ sorption and diffusion on the surface and in the interface layer of VS2/graphene heterostructure with both H and T configurations of VS2 monolayer. The theoretically predicted capacity of VS2/graphene heterostructures is high (569 mAh/g), and the diffusion barriers are considerably lower for the heterostructures than for bulk VS2, so that they are comparable to barriers in graphitic LIB anodes (∼0.2 eV). Our results suggest that VS2/graphene heterostructures can be used as a promising anode material for lithium-ion batteries with high power density and fast charge/discharge rates.

Half-metallic ferromagnetic materials with planar forms are promising for spintronics applications. A wide range of 2D lattices like graphene, h-BN, transition metal dichalcogenides, etc. are non-magnetic or weakly magnetic. Using first principles calculations, the existence of graphene-like hexagonal chromium nitride (h-CrN) with an almost flat atomically thin structure is predicted. We find that freestanding h-CrN has a 100% spin-polarized half-metallic nature with possible ferromagnetic ordering and a high rate of optical transparency. As a possible method for stabilization and synthesis, deposition of h-CrN on 2D MoSe or on MoS is proposed. The formation of composites retains the half-metallic properties and leads to the reduction of spin-down band gaps to 1.43 and 1.71 eV for energetically favorable h-CrN/MoSe and h-CrN/MoS configurations, respectively. Calculation of the dielectric functions of h-CrN, h-CrN/MoSe and h-CrN/MoS exhibit the high transparency of all three low-dimensional nanomaterials. The honeycomb CrN may be considered as a promising fundamental 2D material for a variety of potential applications of critical importance.

The structural, magnetic and electronic properties of 2D VX (X = S, Se) monolayers and graphene/VX heterostructures were studied using a DFT+U approach. It was found that the stability of the 1T phases of VX monolayers is linked to strong electron correlation effects. The study of vertical junctions comprising of graphene and VX monolayers demonstrated that interlayer interactions lead to the formation of strong spin polarization of both graphene and VX fragments while preserving the linear dispersion of graphene-originated bands. It was found that the insertion of Mo atoms between the layers leads to n-doping of graphene with a selective transformation of graphene bands keeping the spin-down Dirac cone intact.

Highlights-The sensor response of fluorinated metal phthalocyanines toward NH 3 was performed.-The sensor response was studied using surface plasmon resonance technique.-The effect of central metal in MPcF 16 molecule to the sensor response was verified.-The structure of analyte/phthalocyanine complex was analysed using DFT calculations.3 A comparative study of the sensor response toward gaseous ammonia of hexadecafluorinated 3d-metal phthalocyanine (MPcF 16 , M=Cu(II), Co(II), Zn(II), Ni(II)) thin films was performed using complementary experimental (viz., surface plasmon resonance, SPR, and IR absorption spectroscopy) along with theoretical (density functional theory calculations, DFT) techniques. SPR measurements revealed changes of both thickness and optical parameters (refraction indices and extinction coefficients) of the MPcF 16 films caused by adsorption of NH 3 . The MPcF 16 species studied exhibited the following order of sensor response: ZnPcF 16 > CoPcF 16  CuPcF 16 > NiPcF 16 . A good correlation was found between the DFT calculated (B3LYP/6-311++G(2df,p)) binding energies, experimentally measured shift of the selected IR bands, and the optical sensor response. Apart from this, we performed a detailed assignment of all intense bands in the vibrational spectra (IR and Raman) of fluorinated 3d-metal phthalocyanines studied.