Van der Waals heterojunctions comprising double/single-walled carbon nanotubes: Insights into heat flux and thermal rectification

Abstract

Van der Waals (vdWs) heterojunctions constructed from double/single-walled carbon nanotubes (DSCNTs) demonstrate exceptional thermal rectification (TR) ratios, coupled with a straightforward fabrication process, making them highly suitable for thermal rectifier applications. In this study, we employed a Nonequilibrium Molecular Dynamics method to investigate the heat flux and TR across DSCNTs with varying interlayer spacings. Our findings reveal that at smaller interlayer spacings, high temperatures readily overcome vdWs interactions. Conversely, increasing the interlayer spacing initially impedes this effect, though elevated temperatures can surmount this barrier. Significantly, at specific combinations of temperature and interlayer spacing, the left side in DSCNTs establishes interlayer phonons transport channels, facilitating forward heat flux but impeding the backward. This mechanism results in an exceptionally high TR ratio, reaching up to 757 %. Additionally, altering the chiral configurations of the CNTs in the inner and outer layers, while preserving interlayer spacing, further enhances the TR ratio and reduces the temperature threshold required to achieve peak TR ratio. Our findings contribute valuable insights into the phonon transport mechanisms within one-dimensional vdWs heterojunctions.