Trigraphene and its Derivates: A Novel Carbon Allotrope

Abstract

A new family of all-carbon structures is proposed via substituting the sp 2 carbon atom in graphene and graphyne with carbon trigons. Owing to the existence of carbon trigons, these porous carbon allotropes are named as trigraphene and trigraphyne. The calculations of geometrical, vibrational, and energetic properties by density functional theory reveal that all these structures are metastable and dynamically stable. It is further disclosed from the electronic band structures that trigraphene and α-trigraphyne are metal, while β-trigraphyne and γ-trigraphyne are semiconductor with indirect band gaps of 0.33 and 0.52 eV, respectively. Our results suggest a strategy to design new carbon materials with desired properties, and these all-carbon materials would have many interesting applications once obtained.

Twin α-trigraphyne: a new two-dimensional carbon material

“…Trigraphene as well as a-trigraphyne possess metallic properties, while band g-trigraphyne are indirect band gap semiconductors. 46 In the present study, we propose a new carbon-based sheet, named twin a-trigraphyne. The structural, mechanical, electronic, and optical properties of twin a-trigraphyne are compared to those of a-trigraphyne.…”

“…[37][38][39][40][41][42][43][44][45] Recently, by replacing carbon trigons instead of sp 2 carbon atoms in graphene and graphyne, new forms of 2D carbon allotropes named trigraphene and trigraphyne have been introduced. 46 It has been shown that these constructed sheets are energetically favorable and dynamically stable. Trigraphene as well as a-trigraphyne possess metallic properties, while band g-trigraphyne are indirect band gap semiconductors.…”

Negative Thermal Expansion Induced in Tri-graphene and T-graphene by the Rigid-Unit Modes

“…11 The angular strain due to the triangular rings reduces the cohesive energy (ΔE coh = +0.9 eV/atom with respect to graphene) and bestows anharmonicity in the system. 8 Typically a material expands on heating, and therefore, positive thermal expansion (PTE) is observed. Nevertheless, several new materials have been found which contract on heating, showing negative thermal expansion (NTE), like oxides, halides, and other minerals, framework materials bridged by ligands like CN − and SCN − .…”

“…T-graphene (TG) and tri-graphene (TrG), having tetra-rings (4-membered rings) and tri-rings (3-membered rings/trigons), respectively, have generated significant interest. , Even in the absence of hexagonal symmetry, planar TG is metallic while buckled TG is proposed to have a graphene-like Dirac cone with linear E ( k ) vs k near the Fermi level. Kim et al showed that buckled TG spontaneously transforms to the planar form .…”

“…TrG has been shown to be metallic by Andrey and Enyashin . The angular strain due to the triangular rings reduces the cohesive energy (Δ E coh = +0.9 eV/atom with respect to graphene) and bestows anharmonicity in the system …”