Properties Of Penta-graphene Research Articles

A New 3D Carbon Allotrope Composed of Penta-graphene Nanotubes with Low Lattice Thermal Conductivity.

Motivated by the unique geometries and novel properties of penta-graphene (PG) and its derivatives, we propose a new stable 3D carbon allotrope, penta-C72, which is composed of PG nanotubes by connecting adjacent tubes in a tip-to-tip manner. Using first-principles calculations, we confirm its dynamical, thermal, and mechanical stabilities and find that penta-C72 is semiconducting with an indirect bandgap of 2.12 eV. Its lattice thermal conductivities at 300 K are found to be anisotropic with values of 97.32 and 179.35 W/mK along the x and z directions, respectively, which are much lower than that of diamond (2664.93 W/mK) and carbon nanotube-based bct-C4 (1411.02 W/mK). A detailed analysis of both harmonic and anharmonic properties suggests that the soften acoustic phonon modes, the low Young's modulus, and strong anharmonicity are the key factors for the low lattice thermal conductivity. The study expands the family of carbon materials by assembling PG nanotubes.

Effect of the co-adsorption of small molecules from air on the properties of penta-graphene and their proton transfer calculation.

Penta-graphene has attracted considerable attention due to its unique structure and novel properties. Herein, we studied the effect of the co-adsorption of small molecules from air on the properties of penta-graphene using first-principles calculations. Our results show that oxygen molecules can be self-decomposed on the surface of penta-graphene and the process of O2 decomposition is an exothermic reaction. On the contrary, the adsorption of H2O or N2 molecule on penta-graphene exhibits weak interaction characteristic. For co-adsorption systems, the adsorption of N2 molecule has no effect on the electronic properties of penta-graphene because the N2 molecule is more inert than other molecules. Hydrogen bonds (H-bonds) have been observed in the co-adsorption of H2O and O2 on penta-graphene. We find that shorter H-bonds lead to higher stability of the systems. We also explore the proton transfer process between H2O and oxidized penta-graphene. Our results show that the proton transfer process is relatively difficult due to the high energy barrier. However, double-proton transfer is an exothermic process since the energy of the final state is 0.11 eV lower than that of the initial state. These results indicate that the configuration of oxidized penta-graphene is complicated. Our research provides a theoretical basis and important guidance for the experimental synthesis and functionalization of penta-graphene.

Interfacial properties of penta-graphene-metal contacts

Novel properties of penta-graphene (PG) have stimulated great interest in exploring its potential for device applications. Here, we systematically study the interfacial properties of the heterojunctions constructed by stacking PG on several metal substrates (Ag, Al, Au, Cr, Cu, Pd, and Ti), which are commonly used in field-effect transistors. We consider PG as the channel material because of its semiconducting feature, while treating the metal surfaces as the electrodes. Based on first principles calculations, we show that PG preserves its pentagonal feature with some small distortions when deposited on the metal substrates but undergoes metallization due to the chemical bonding between PG and the metal surfaces. We evaluate the device potential of these PG-metal contacts by studying their tunneling barriers, orbital overlaps, and Schottky barriers. We find that PG forms an n-type Schottky barrier when in contact with Al, Cu, and Ti, but forms a p-type Schottky barrier when supported on Ag, Au, Cr, and Pd. Our study sheds light on the design and fabrication of PG-based electronic devices.

2D carbon sheets with negative Gaussian curvature assembled from pentagonal carbon nanoflakes.

Despite the good progress made in materials fabrication, it remains a big challenge to synthesize 2D sheets by assembling nanoflakes that are usually produced in experiments, and few theoretical studies have explored this topic. Based on the recent experimental synthesis of pentagonal graphene nanoflakes and the novel properties of penta-graphene, we report a series of 2D assembled carbon allotropes (CG568-80, CG568-180 and CG568-320) that have the following unusual properties: different from most other 2D carbon allotropes, the assembled carbon sheets have negative Gaussian curvatures, and exhibit ultra-softness and better chemical reactivity due to the curvature-induced misalignment of π-orbitals as compared with pristine graphene; all three studied carbon sheets are highly stable with binding energies comparable to those of phagraphene and ψ-graphene, and are semiconductors with tunable band gaps, displaying size-dependent carrier mobilities: ∼105 cm2 V-1 s-1 (CG568-80 and CG568-320) and ∼104 cm2 V-1 s-1 (CG568-180). These features indicate that assembling nanoflakes can effectively tune the structural morphology and properties to expand the family of 2D carbon materials for future applications.