Tunable thermal conductivity in carbon allotrope sheets: Role of acetylenic linkages

Abstract

The versatility of carbon in forming the hybridization states allows one to design more carbon allotropes with various fascinating properties by replacing some aromatic bonds with acetylenic linkages. We investigate thermal conductivities of carbon allotrope sheets with different configurations by nonequilibrium molecular dynamic simulations. It is found that the acetylenic linkages not only considerably reduce thermal conductivity but also can effectively tune thermal conductivity through the various bonding methods. We suggest that the structure of stripes of benzene rings transversely bonded with the acetylenic linkages can potentially be one of high thermoelectric materials. We find that the reason for the manipulation of thermal conductivity by the acetylenic linkage can be attributed to the strong localizations of phonon modes that result in the reduced phonon group velocity and the shortened lifetime of phonons. It is also observed that thermal conductivity of graphyne sheet shows a power-law divergence with respect to the length. We propose a new approach to manipulating thermal conductivities in the carbon allotropes through the assembling of acetylenic linkages. Our findings conclusively clarify the role of acetylenic linkages in thermal transport and offer some valuable insights into the exploration of new thermoelectric materials as well as the experimental control of heat flux.

Anisotropic elastic modulus, high Poisson's ratio and negative thermal expansion of graphynes and graphdiynes

“…This indicates the possibility to use them in electronic nanodevices instead of graphene [7]. Generally speaking, GYs can be good electrical conductors or semiconductors [3][4][5][6][7][8][9][10], are predicted to present higher conductivity than graphene [11,12], have smaller in-plane stiffness than graphene, what depends on the number of acetylenic or diacetylenic linkages [13][14][15][16][17][18][19][20][21][22][23][24][25][26], and have much lower thermal conductivity than graphene [9,[27][28][29][30]. Good electrical and poor thermal conductivity form a good combination for possible applications of GYs in thermoelectrics [27][28].…”

Lattice thermal conductivity of penta-graphene

“…However, when the geometrical structure is modified to graphyne or graphdiyne by introducing acetylenic units (-C≡C-) between the carbon hexagons, the K lat is substantially reduced as compared to that of graphene. This is due to the low atomic density in the sp and sp 2 hybridized structures and the weak single bonds between the carbon atoms [7][8][9][10]. This shows that the intrinsic K lat has an intimate relationship with the topological arrangement of carbon atoms.…”

Carbon Nanomaterial-Based Nanofluids for Direct Thermal Solar Absorption

“…Therefore, modeling and simulation have played an important role in developing an understanding of graphene’s properties. The current simulation methods to understand the heat transfer in graphene as well as predict its thermal properties are molecular dynamics (MD), Boltzmann transport equation (BTE), and non-equilibrium Green’s functions (NEGF) simulations [ 64 , 65 ].…”