Computational Study of the Thermal Rectification Properties of a Graphene-Based Nanostructure

Abstract

Thermally rectifying materials would have important implications for thermal management, thermal circuits, and the field of phononics in general. Graphene-based nanostructures have very high intrinsic thermal conductance, but they normally display no thermal rectification effects. The present study relates to a thermally rectifying material and, more particularly, to a graphene-based nanomaterial for controlling heat flux and the associated method determining the rectification coefficient. Thermal rectifiers using a graphene-based nanostructure as thermal conductors were designed. Vacancy defects were introduced into one end of the nanostructure to produce an axially non-uniform mass distribution. Modified Monte Carlo methods were used to investigate the effects of defect size and shape, vacancy concentration, and ribbon length on the thermal rectification properties. Anharmonic lattice dynamics calculations were carried out to obtain the frequency-dependent phonon properties. The results indicated that the nanoscale system conducts heat asymmetrically, with a maximum available rectification coefficient of about 70%. Thermal rectification has been achieved, and the difference in temperature dependence of thermal conductivity is responsible for the phenomenon. Defects can be tailored to modulate the temperature dependence of thermal conductivity. The power-law exponent can be negative or positive, depending upon the ribbon length and vacancy concentration. A computational method has been developed, whereby the numerous variables used to determine the rectification coefficient can be summarized by two parameters: the power-law exponent and the thermal resistance ratio. Accordingly, the rectification coefficient can be obtained by solving a simple algebraic expression. There are several structure factors that cause noticeable effects on the thermal rectification properties. Defect size, vacancy concentration, and ribbon length can affect the thermal conductance of the nanostructure symmetrically and significantly. Graphene-based nanostructure thermal rectifiers can be arranged in an array so as to provide thermal rectification on a macroscopic scale.

A one-way street for phonon transport: past, present and future of solid-state thermal rectification

“…Higher rectification factors were later obtained in other systems with a gradual variation of some structural feature, namely graphene [13] and Si membranes [14], presenting an asymmetric distribution of defects. The behavior was well understood and backed by theoretical calculations [19][20][21][22], to the extent that more elaborated designs that could yield enhanced rectifications were proposed [23]. Those devices behaved, at least to some extent, as thermal diodes because of the difference between accumulating defects next to the cold or to the hot side: in the former case they reduce considerably the conductance by adding additional scattering; in the latter case phonon scattering is already dominated by high temperature anharmonic effects and adding structural imperfections has little effect.…”

Understanding neural network tuned Langevin thermostat effect on predicting thermal conductivity of graphene-coated copper using nonequilibrium molecular dynamics simulations

“…Graphene is a class of carbon allotropes with an extremely high thermal conductivity that has been heralded as a promising material for a wide range of heat dissipation. Consequently, tremendous research efforts have been devoted to discovering graphene and its incorporation in the thermal and electronic industries [9]. The outstanding mechanical, electrical, and thermal properties of graphene make it one of the best candidate elements in producing composites and hybrid systems.…”

Managing the surface piezoelectricity effect of the smart ZnO sandwich nanoplates using metal foam core layer and GPRL reinforced rim layers

“…The thermal transport properties of nanostructured materials can be influenced by atomic structure and phonon properties, impacting fields like thermoelectrics and thermal insulation [29,30]. Additionally, parameters such as defect size, vacancy concentration, and ribbon length can affect the thermal conductivity of nanostructures [31]. Nanostructuring has been found to enhance properties like thermal shock resistance by reducing thermal conductivity, thereby protecting samples during thermal shocks [32,33].…”