Stability and energy characteristics of extended nitrogen nanotubes: density functional theory study

Abstract

We apply the density functional theory with B3LYP exchange-correlation energy functional and the basis set 6-31G(d) to investigate structural, energetic, and electronic properties and stability of extended armchair and zigzag nitrogen nanotubes with a length of ≈ 3 nm. The capping effect, as well as the passivation of nanotubes' ends by hydrogen atoms and hydroxyl groups on their stability, are studied. According to our calculations, pristine nitrogen nanotubes are unstable. Both capping and passivation of the nanotube ends provide thermodynamic stability only for (3, 0) and (4, 0) zigzag nitrogen nanotubes. Moreover, the calculated frequency spectra of considered systems confirm their dynamic stability. We stress the fact that some extended nitrogen nanotubes are found to be stable under ambient conditions, i. e., in the absence of external factors such as pressure, spatial confinement, etc. The calculated HOMO-LUMO gaps for these stable extended systems are of the order of 4 eV, so they can be assigned to the class of insulators. It is shown that nitrogen nanotubes are able to store a large amount of energy and can be used as a basis for new high-energy-density materials. We expect that the all-nitrogen tubes with the longer effective length of similar chiralities are also should be stable.

Molecular and Electronic Structures of Neutral Polynitrogens: Review on the Theory and Experiment in 21st Century

“…This variety in polynitrogens was the subject of publications [ 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 , 111 , 112 , 113 , 114 , 115 , 116 , 117 , 118 ]. For example, in [ 103 ], a polymeric form of nitrogen was reported, where all atoms are linked by single covalent bonds, similar to carbon atoms in a diamond; this compound was synthesized directly from molecular dinitrogen at temperatures above 2000 K and pressures above 110 GPa using a laser heated diamond cell.…”

“…The possibility of the existence of other forms of polymeric nitrogen containing only single N–N bonds was also noted: layered, existing in the pressure range P = 188–320 GPa [ 107 , 108 ]; helical tunnelling, existing at P > 320 GPa [ 107 ]; sheet zigzag [ 109 , 110 ]; trigonal [ 111 ]; and even metal [ 112 , 113 , 114 ] (although it is very difficult to assume that nitrogen atoms, due to their high electronegativity, can participate in the formation of metal bonds!). The existence of polymeric nitrogen, having a “parquet” structure and composed of N6 hexagons, and resembling the structure of black phosphorus or graphite [ 115 ], and also in the form of nanotubes [ 116 ], is possible. Finally, in the most recent work [ 117 ], a new class of polymeric nitrogen molecules was investigated, consisting of several intergrown nanotubes of nanometer length—astralenes, which, depending on the shape of the central part (core), can be divided into cubic, hexagonal, and tetrahedral.…”

All-Nitrogen Cages and Molecular Crystals: Topological Rules, Stability, and Pyrolysis Paths

“…The extremely small diameters of these tubes provide stability due to the curvature effects and concave hexagon shapes. It should be noted that the large diameter N n tubular structures are unstable [46]. We tested the stability of the tubular systems shown in Figure 2 using ab initio molecular dynamics (AIMD) at T = 700 K for one picosecond.…”

Low pressure metastable single-bonded solid nitrogen phases

“…[32][33][34][35][36][37][38][39] During further theoretical calculations, many different solid atomic phases of nitrogen have been predicted. [40][41][42][43] However, among nitrogen crystals with a three-dimensional structure, dynamic stability at zero pressure is theoretically predicted only for the Gauche phase (I2 1 3), 31 as well as phases with lattice symmetries Pccn, 40 R% 3, 41 and P% 62c. 42 A comprehensive theoretical study of two-dimensional polynitrogen and hybrid nitrogen materials was carried out in ref.…”