Thermal Properties of Isotopically Engineered Graphene

TL;DR

This study investigates how isotopic composition affects graphene's thermal conductivity, revealing that pure 12C graphene exhibits significantly higher thermal conductivity than mixed isotopic versions, supported by experimental and simulation data.

Contribution

First experimental measurement of isotope effects on graphene's thermal conductivity using CVD synthesis and Raman techniques, validated by molecular dynamics simulations.

Findings

Pure 12C graphene has thermal conductivity over 4000 W/mK.

Mixed isotopic graphene shows more than two times lower conductivity.

Experimental results align with molecular dynamics simulations.

Abstract

In addition to its exotic electronic properties graphene exhibits unusually high intrinsic thermal conductivity. The physics of phonons - the main heat carriers in graphene - was shown to be substantially different in two-dimensional (2D) crystals, such as graphene, than in three-dimensional (3D) graphite. Here, we report our experimental study of the isotope effects on the thermal properties of graphene. Isotopically modified graphene containing various percentages of 13C were synthesized by chemical vapor deposition (CVD). The regions of different isotopic composition were parts of the same graphene sheet to ensure uniformity in material parameters. The thermal conductivity, K, of isotopically pure 12C (0.01% 13C) graphene determined by the optothermal Raman technique, was higher than 4000 W/mK at the measured temperature Tm~320 K, and more than a factor of two higher than the value of K in a graphene sheets composed of a 50%-50% mixture of 12C and 13C. The experimental data agree well with our molecular dynamics (MD) simulations, corrected for the long-wavelength phonon contributions via the Klemens model. The experimental results are expected to stimulate further studies aimed at better understanding of thermal phenomena in 2D crystals.