Phonon thermal transport in a class of graphene allotropes from first principles

Utilizing first principle calculations combined with the phonon Boltzman transport equation (PBTE), we systematically investigate the phonon thermal transport properties of α, β and γ graphyne, a class of graphene allotropes. Strikingly, at room temperature, a low lattice thermal conductivity κL of 21.11, 22.3, and 106.24 W m-1 K-1 is obtained in α, β and γ graphyne, respectively, which are much lower than that of graphene. We observe contributions from the phonon modes below the specified frequency and find that many optical phonon modes play critical roles in the phonon thermal transport. These optic modes participate in thermal transport, enhancing the phonon scattering process, thus leading to the low κL value. Our results provide insights into the thermal transport of graphyne, and forecast its potential applications for thermoelectric and thermal barrier coatings.