In a recent paper [Physical Review B 95, 165428 (2019)], M. Saiz-Bretín et al argue that graphene nanorings attached to two leads show increased phonon scattering while keeping good electron transport. Using a density-functional parametrized tight-binding method combined with Green’s function technique, they show that the lattice thermal conductance is largely reduced as compared to that of graphene nanoribbons. At the same time, numerical calculations based on the quantum transmission boundary method, combined with an effective transfer matrix method, predict that the electric properties are not considerably deteriorated, leading to an overall remarkable thermoelectric efficiency. They conclude that graphene nanorings can be regarded as promising candidates for nanoscale thermoelectric devices.

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