A First-Principle Theoretical Study of Mechanical and Electronic Properties in Graphene Single-Walled Carbon Nanotube Junctions.

Ning Yang,Xuejun Fan,Dongjing Liu,Liangbiao Chen,Daoguo Yang,Miao Cai

doi:10.3390/ma10111300

Ning Yang, Xuejun Fan + Show 4 more

Open Access

https://doi.org/10.3390/ma10111300

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Abstract

The new three-dimensional structure that the graphene connected with SWCNTs (G-CNTs, Graphene Single-Walled Carbon Nanotubes) can solve graphene and CNTs′ problems. A comprehensive study of the mechanical and electrical performance of the junctions was performed by first-principles theory. There were eight types of junctions that were constituted by armchair and zigzag graphene and (3,3), (4,0), (4,4), and (6,0) CNTs. First, the junction strength was investigated. Generally, the binding energy of armchair G-CNTs was stronger than that of zigzag G-CNTs, and it was the biggest in the armchair G-CNTs (6,0). Likewise, the electrical performance of armchair G-CNTs was better than that of zigzag G-CNTs. Charge density distribution of G-CNTs (6,0) was the most homogeneous. Next, the impact factors of the electronic properties of armchair G-CNTs were investigated. We suggest that the band gap is increased with the length of CNTs, and its value should be dependent on the combined effect of both the graphene’s width and the CNTs’ length. Last, the relationship between voltage and current (U/I) were studied. The U/I curve of armchair G-CNTs (6,0) possessed a good linearity and symmetry. These discoveries will contribute to the design and production of G-CNT-based devices.

Highlights

The novel three-dimensional structure that graphene connected with carbon CNTs (G-CNTs) is currently receiving much attention
The methods of density functional theory (DFT) and density functional based tight binding (DFTB) were used in our study for the calculations of different G-CNTs
The calculations of the junctions of G-CNTs were performed by DFT, a kind of quantum mechanics mechanics researching for the electronic structure of the multi-electron system

Summary

Introduction

The novel three-dimensional structure that graphene connected with carbon CNTs (G-CNTs) is currently receiving much attention. Like graphene and CNTs, the G-CNTs has excellent mechanical and electrical properties It can solve the problems of the agglomeration of graphene and the intertwining of CNTs. G-CNTs have been used in many applications such as transparent conductors [1], supercapacitors [2], batteries [3], biosensors [4], and gas detection [5]. Graphene and CNTs are the most promising 2-D materials for the industry [6,7] They have excellent mechanical and electrical properties [8,9]. The methods of DFT and DFTB were used in our study for the calculations of different G-CNTs. In this paper, the different connected ways were discussed via DFT, such as the structures of armchair and zigzag graphene connected (3,3), (4,0), (4,4), and (6,0) CNTs The band conductance is nearly independent of the tube length but changes

Results and Discussion

The Impact Factors on the Electronic Properties of G-CNTs

The Relationship between Voltage and Current of Armchair G-CNTs

Theory and Simulations

N Zα Zβ

Conclusions