A comparative study of the electronic and thermal properties of a-graphyne and a-graphdiyne nanoscrolls: Implications for thermoelectric applications

J de Lima and LV Bastos and CF Woellner, COMPUTATIONAL MATERIALS SCIENCE, 250, 113728 (2025).

DOI: 10.1016/j.commatsci.2025.113728

Graphynes (GYs) and graphdiynes (GDYs) are 2D carbon allotropes featuring both sp and sp2 hybridized carbon atoms, differentiated by the number of acetylenic groups: one in GYs and two in GDYs. This study investigates the electronic and thermal properties of a-GY and a-GDY, comparing them to graphene. Through Equilibrium Molecular Dynamics (EMD) simulations and Density Functional Theory (DFT) calculations, we demonstrate that acetylenic groups significantly reduce the thermal conductivity (x) of a-GY and a-GDY, typically by one order of magnitude compared to graphene. This reduction is primarily due to the lower atomic density and weaker sp-type bonds in these structures, which lead to flatter phonon dispersion curves and reduced phonon group velocities. Nanoscrolls, rolled-up configurations of these materials, exhibit even lower thermal conductivity than their planar counterparts. For all configurations, x decreases with increasing temperature up to 500 K. Notably, a-GDY shows less sensitivity to variations in temperature compared to a-GY. Despite the reduced thermal conductivity introduced by acetylenic groups, a-GY and a-GDY retain a zero band gap semiconducting nature, similar to graphene. These findings highlight the potential of these materials as promising candidates for thermoelectric applications, where the combination of semiconducting behavior and low thermal conductivity is highly desirable.

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