Thermal rectifiers based on asymmetric van der Waals heteronanotubes.

Efficient thermal management at the nanoscale is essential for advanced electronic applications. In this work, we explore the thermal rectification properties of asymmetric van der Waals heteronanotubes, e.g., a single-walled carbon nanotube (CNT) partially coated by a single-walled molybdenum disulfide nanotube (MoS2NT), which have been successfully synthesized in recent experiments. Through extensive molecular dynamics simulations, we demonstrate that these heteronanotubes can effectively function as thermal rectifiers, with rectification ratios surpassing 100% under substantial temperature gradients. The analyses based on the phonon density of states and the velocity autocorrelation function reveal key insights into the underlying mechanisms. In addition to the phonon-spectrum mismatch, the MoS2NT sheath suppresses radial vibrations on the covered CNT segment, leading to a prominent 13 THz standing wave mode at the exposed CNT end under reverse bias, which traps vibrational energy and impedes reverse heat flux. The thermal rectification remains robust across variations in the average temperature, device size, inter-tube spacing, diameter of heteronanotubes, and MoS2NT coverage fraction, underscoring the potential for scalable and fault-tolerant applications. These findings highlight the promise of heteronanotubes in nanoscale thermal management, offering a novel approach for controlling heat flow in advanced electronic devices, thermal diodes, and other nanoscale systems.