Selective Hydrogenation Promotes the Anisotropic Thermoelectric Properties of TPDH-Graphene

Abstract

We have combined density functional theory calculations with the Boltzmann semiclassical transport theory to investigate the effect of selective hydrogenation on the thermoelectric properties of tetra-penta-decahexagonal graphene (TPDHgr), a recently proposed new two-dimensional carbon allotrope. Our results show that the Seebeck coefficient is enhanced after hydrogenation. The conductivity along the x direction is increased almost eight times while being almost suppressed along the y direction. This behavior can be understood in terms of the electronic structure changes due to the appearance of a Dirac-like cone after selective hydrogenation. Consistent with the literature, the electronic contribution to the thermal conductivity displays the same qualitative behavior as the conductivity, as expected from the Wiedemann−Franz law. The increase in thermal conductivity with temperature limits the material's power factor. The significant increases in the Seebeck coefficient and conductivity also contribute to the thermal conductivity increase. These results show that hydrogenation is an effective method to improve the TPDH-gr thermoelectric properties, and this carbon allotrope can be an effective material for thermoelectric applications.