Multiporous carbon allotropes transformed from symmetry-matched carbon nanotubes

Abstract

Carbon nanotubes (CNTs) with homogeneous diameters have been proven to transform into new carbon allotropes under pressure but no studies on the compression of inhomogeneous CNTs have been reported. In this study, we propose to build new carbon allotropes from the bottom-up by applying pressure on symmetry-matched inhomogeneous CNTs. We find that the (3,0) CNT with point group C3v and the (6,0) CNT with point group C6v form an all sp3 hybridized hexagonal 3060-Carbon crystal, but the (4,0) CNT with point group D4h and the (8,0) CNT with point group D8h polymerize into a sp2+sp3 hybridized tetragonal 4080-Carbon structure. Their thermodynamic, mechanical and dynamic stabilities show that they are potential carbon allotropes to be experimentally synthesized. The multiporous structures, excellently mechanical properties and special electronic structures (semiconductive 3060-Carbon and semimetallic 4080-Carbon) imply their many potential applications, such as gases purification, hydrogen storage and lightweight semiconductor devices. In addition, we simulate their feature XRD patterns which are helpful for identifying the two carbon crystals in future experimental studies.

Endocircular Li Carbon Rings

“…Carbon allotropes are both simple and complex at the same time.T hey are simple,b ecause they are made of only one elementary substance in relatively high symmetries. [1][2][3] On the other hand, they are molecules with many geometrical structures,e .g., spherical fullerenes, [4] planar graphenes, [5] cylindrical carbon nanotubes, [6] carbon cyclic rings, [7] etc. Their large variety in geometry results in intriguing complex electronic structures.F or example,f ullerenes can form both compacted valence bound states (hybridizing from valence orbitals), and diffuse superatomic bound states (hybridizing from higher unoccupied orbitals), [8][9][10][11][12][13][14][15] when they accept an extra electron.…”

A sp2+sp3 hybridized carbon allotrope transformed from AB stacking graphyne and THD-graphene

“…The two wide phonon bandgaps enable TBBC to be used for acoustic filtering, waveguiding, focusing, noise control, and vibrational control for mechanical systems. As far as thermodynamic stability, the total energy of TBBC is 0.69 eV/atom higher than that of graphite, 25 but 0.06 eV/atom less than that of graphdiyne which has been experimentally synthesized by Li et al 4 In other words, the cohesive energy of TBBC is 0.06 eV/atom higher than that of graphdiyne. Therefore, TBBC is thermodynamic stable.…”

“…Similarly, multiporous carbons are obtained by applying pressure on nanotubes. 25 Likewise, the α-C, β-C and γ-C are predicted to be obtained by transversely compressing (3,3) CNTs. 25 And an all sp 3 hybridized hexagonal 3060-Carbon is achieved by compressing the (3,0) and (6,0) CNTs, and a sp 2 +sp 3 hybridized tetragonal 4080-Carbon is obtained by compressing the (4,0) and (8,0) CNTs.…”

“…25 Likewise, the α-C, β-C and γ-C are predicted to be obtained by transversely compressing (3,3) CNTs. 25 And an all sp 3 hybridized hexagonal 3060-Carbon is achieved by compressing the (3,0) and (6,0) CNTs, and a sp 2 +sp 3 hybridized tetragonal 4080-Carbon is obtained by compressing the (4,0) and (8,0) CNTs. 26 These studies show that carbon allotropes with low coordination numbers could be used as building blocks to prepare new carbon materials under pressure.…”

Electronic, Mechanical and Elastic Anisotropy Properties of X-Diamondyne (X = Si, Ge)

“…Carbon atoms have many ways of hybridizing in nature and can assume many allotropic forms [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]. Diamond is a typical sp 3 hybrid product.…”