Porous graphene and graphenylene nanotubes: Electronic structure and strain effects

Abstract

a b s t r a c tThe unusual and unique mechanical and electronic properties of nanostructured carbon materials make them useful in the construction of nanodevices. We investigate a new class of structures, called porous nanotubes, which are constructed from two recently synthesized two-dimensional materials, namely the porous graphene (PG) and the two-dimensional carbon allotrope known as graphenylene, also known as Biphenylene Carbon (BPC). We investigate this class of quasi-one-dimensional materials using the density functional tight-binding (DFTB) method to optimize geometries and to calculate electronic structure features of these systems. For each type of porous nanotube, calculations were performed on tubes with several diameters and chiralities. Our results show that the PG nanotubes have a wide band-gap, $ 3:3 eV, and the graphenylene nanotubes have a semiconductor behavior with a band gap around 0.7 eV. They also show that as the diameter of a PG nanotube increases the band-gap decreases, while for the graphenylene nanotube the band gap increases. In both cases, the observed gap variation with increasing diameter is towards the value found for the respective two-dimensional membrane. Calculations on axially strained porous nanotubes show a decrease on the band gap of $ 10% for some chiralities of the PG nanotube and an increase for the graphenylene nanotubes gap that can become as high as 100%. These results are in contrast with the expected behavior for carbon nanotubes, which show a linear dependence between gap opening and applied strain under similar conditions.

Piezoelectric Response of Porous Nanotubes Derived from Hexagonal Boron Nitride under Strain Influence

“…43 The difference in results was due to the well-known fact that the PBE functional underestimates the band gap energy; however, considering whether the band gap is direct or indirect, our results were coincident for both chiralities. Also, when compared with a previous theoretical study 40 that utilized the DFTB methodology, the band gap behaviors for PGNTs and GPNTs were also in agreement, and the trend observed in the diameter dependence of the band gap was in reasonable agreement with this work.…”

“…Fabris et al 40 studied PG nanotubes (PGNTs) and GPNTs for nanotubes with diameters less than 56 Å using the DFTB method, which showed that PGNTs have a wide band gap of ∼3.3 eV, whereas GPNTs have a small band gap of ∼0.7 eV. They also showed that as the diameter of the PGNTs increases, the band gap decreases, whereas for GPNTs, the band gap increases with the PGNT diameter; these results are in agreement with those presented by Koch.…”

“…37,38 In 2015, Koch et al 39 proposed GP nanotubes (GPNTs) and used plane-wave density functional theory (DFT) combined with a Perdew−Burke−Ernzerhof (PBE) functional [in comparison with the density functional tight binding (DFTB)] to calculate metallic characteristics for armchair nanotubes with small diameters and small band gap semiconducting characteristics for nanotubes with larger diameters; they also show that GPNTs also have a promising lithium storage application because it retains their mechanical properties during charging cycles. Fabris et al 40 studied PG nanotubes (PGNTs) and GPNTs for nanotubes with diameters less than 56 Å using the DFTB method, which showed that PGNTs have a wide band gap of ∼3.3 eV, whereas GPNTs have a small band gap of ∼0.7 eV. They also showed that as the diameter of the PGNTs increases, the band gap decreases, whereas for GPNTs, the band gap increases with the PGNT diameter; these results are in agreement with those presented by Koch. Although there have been several studies on carbon-based porous nanotubes, as described above, more detailed studies on the properties of these structures are required, such as on the elastic, piezoelectric, and vibrational properties.…”

The Effect Of Sulphur (S) Doping and K+ Adsorption To The Electronic Properties Of Graphene: A Study By DFTB Method

“…The result shows a large band gap with an energy of 3.3 eV. Meanwhile, a nanotube graphenylene has a band gap energy of 0.7 eV [19] .…”

Graphenylene nanoribbons: electronic, optical and thermoelectric properties from first-principles calculations

“…By DFT calculations, they showed that graphenylene nanotubes with 'zigzag' edges are semiconductors with a small bandgap values, while narrow 'armchair' tubes exhibit metallic properties and become semiconducting for increased diameters. In [14], computational results on electronic structure and strain effects of porous graphene and graphenylene nanotubes are presented and analyzed. Fabris et al [14] have found that axial strain applied to graphenylene nanotubes can lead to substantial increase of the bandgap (up to 100% in some cases).…”