Unconventional thermal conductivity of suspended zigzag graphene nanomesh

TL;DR

This study fabricates atomically precise zigzag graphene nanomeshes and investigates their thermal conductivity, revealing unconventional size-dependent behavior due to the mesh structure and edge order, with implications for thermal management.

Contribution

It introduces a method to create atomically precise zigzag graphene nanomeshes and explores their unique thermal conductivity properties, contrasting with traditional graphene nanoribbons.

Findings

Thermal conductivity of 2-3 ML zGNMs inversely relates to nanoribbon width.

Thermal conductivity of 5-10 ML zGNMs is independent of width down to 30 nm.

zGNRs with atomically ordered zigzag edges have higher thermal conductivity than rough-edged GNRs.

Abstract

Compared to the study of graphene itself, the study of nano-structured graphene is rather limited because it is difficult to prepare atomically ordered edges. In this study, we have fabricated a periodically patterned mesh structure of graphene with atomically precise zigzag edges (zGNM: zigzag graphene nanomesh) and studied its thermal conductivity ($\kappa$) by opto-thermal Raman measurement. Unintuitively, it is found that the $\kappa$ of zGNM of 2,3 monolayers (MLs) thick is inversely proportional to the nanoribbon width ($W$), while that of zGNM of 5$\sim$10 MLs thick is independent of $W$ down to 30 nm. Since the $\kappa$ of suspended zigzag graphene nanoribbons (zGNRs) is suppressed by decreasing $W$, this nonclassical behavior of zGNM is due to the mesh structure. In addition, zGNRs show a higher $\kappa$ than GNRs with atomically rough edges. This is probably due to the atomically ordered zigzag edges.