A comparative study of stability, structural, and elastic properties of single-wall noncarbon nanotubes, including BN, AlN, GaN, AlP, GaP, and B nanotubes using ab initio simulation is presented. The proposed nanotubes can be found in nature, which is confirmed by calculation of their binding energy. The values of Young's modulus and Poisson's ratio for (0,$n$) and ($n,n$) proposed nanotubes with $n=3\cdots 20$ are obtained. The conception of two-dimensional (2D) Young's modulus of planar and tubular materials was developed. The calculations show that stable forms of boron nitride nanotubes have the 2D Young's modulus almost similar to carbon nanotubes. At the same time, it is stated that boron nanotubes have a higher 2D Young's modulus than any other known carbon and noncarbon nanostructures.

In this paper a covalent assembly of two two-dimensional (2D) materials is investigated. It is shown that borophene with periodic perforation (as one of numerous 2D boron nanoallotropes) and graphenylene can form the vertical heterostructure. This borophene-graphenylene bilayer reduces the dynamic instability inherent in certain types of 2D boron. A detailed study of the nature of the interatomic bonds shows that covalent forces and van der Waals forces act alternately between a pair of neighboring boron and carbon atoms. The electronic and mechanical properties of the predicted heterostructure are comprehensively investigated: in the equilibrium condition, under strain, and with passivation by atomic hydrogen. Several calculation schemes are used to increase the accuracy of the electronic structure calculations. It is shown that the tension and the passivation of borophene-graphenylene from the carbon layer by hydrogen can strongly affect the band gap. The mechanical properties of this heterostructure correspond to the properties of one of its materials, graphenylene. The use of this material to stabilize 2D boron nanoallotropes, as well as in flexural nanoelectronics, is promising.

Recently synthesized two-dimensional graphene-like material referred to as graphenylene is a semiconductor with a narrow direct bandgap that holds great promise for nanoelectronic applications. The significant bandgap increase can be provided by the strain applied to graphenylene crystal lattice or by using nanoribbons instead of extended layers. In this paper, we present the systematic study of the electronic, optical and thermoelectric properties of graphenylene nanoribbons using calculations based on the density functional theory. Estimating the binding energies, we substantiate the stability of nanoribbons with zigzag and armchair edges passivated by hydrogen atoms. Electronic spectra indicate that all considered structures could be classified as direct bandgap semiconductors. From the calculated dependence of bandgap on nanoribbon width we observe the identical scaling rule for armchair and zigzag graphenylene ribbons. A family-based classification used for the electronic structure of armchair graphene nanoribbons can not be extended to the case of graphenylene ones. The absorption coefficient, optical conductivity, and complex refractive index are calculated by means of the first-principles methods and the Kubo–Greenwood formula. It has been shown that graphenylene ribbons effectively absorb visible-range electromagnetic waves. Due to this absorption the conductivity is noticeably increased in this range. The transport coefficients and thermoelectric figure of merit are calculated by the nonequilibrium Green functions method. Summarizing the results, we discuss the possible use of graphenylene films and nanoribbons in nanoelectronic devices.