▎ 摘　　要

Structuring graphene has led to a wealth of opportunities to enhance or at least to alter its electronic, optical and thermal properties. E.g, punching holes in graphene in the form antidot lattices turns the base material from a semimetal into a semiconductor. In here, we aim at leaving graphene pristine, but instead growing h-BN nanorings on top of it with the desire to alleviate heat spread by virtue of a reduced thermal conductivity. By combining empirical molecular dynamics and Green-Kubo simulations, we predict that using thinner nanorings leads to rapidly decaying heat currents and therefore remarkably reduced thermal conductivities by 76% in comparison to graphene. Interestingly, we also argue how an applied electric field breaks the underlying crystal symmetry enabling directionally tunable thermal transport. We foresee exciting possibilities to subdue optical and plasmonic loss channels by reduced thermal dissipation.