Thermal Conductivity of Graphene Oxide: A Molecular Dynamics Study
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Thermal Conductivity of Graphene Oxide: A Molecular Dynamics Study1) J. Chen2) , L. Li Department of Energy and Power Engineering, School of Mechanical and Power Engineering, Henan Polytechnic University, Jiaozuo, 454000 Henan, Peoples republic of China Submitted 30 May 2020 Resubmitted 9 June 2020 Accepted 9 June 2020
The thermal properties of graphene oxide containing hydroxyl and epoxy functional groups were studied using non-equilibrium molecular dynamics to understand the thermal transport phenomena involved and the structure factors limiting heat conduction. Estimates were given in terms of phonon mean free paths for the reduction in thermal conductivity by interior defects due to scattering. The mechanism of phonon transport in the graphene oxide was discussed. The results indicated that the degree of oxidation can significantly affect the thermal performance of graphene oxide. A low degree of oxidation is necessary to enhance the phonon transport properties of graphene oxide and reduce the probability of phonon-defect scattering. Phonon transport in graphene oxide with a high degree of oxidation is governed by the mean free path of phonons associated with scattering from interior defects. Oxygen-containing functional groups can adversely affect performance and reduce the efficiency of phonon transport in graphene oxide due to phonon mean free paths limited mainly by interior defects. The calculated intrinsic thermal conductivity of graphene oxide at room temperature is about 72 W/m · K with an oxidation degree of 0.35 and about 670 W/m · K with an oxidation degree of 0.05. The phonon mean free path decreases with increasing the degree of oxidation due to enhanced phonon-defect scattering, making the thermal conductivity very sensitive to the concentration of oxygen-containing functional groups. DOI: 10.1134/S0021364020140015
1. Introduction. Graphene is a particularly unique form of carbon that can possess a number of desirable properties [1, 2]. The carbon atoms in graphene are densely packed in a regular two-dimensional hexagonal pattern. This atomic structure of graphene enables it to conduct heat and electricity with great efficiency [3, 4]. In effect, graphene can dissipate heat more efficiently than copper or aluminum [5, 6]. Many studies have focused on the thermal properties of pristine graphene [7] and the use of this two-dimensional material as a thermally conductive filler material in metal and polymer matrix composite materials with increased thermal properties [8]. However, the potential has not been fully exploited [9]. Various methods have been presented to possibly utilize non-continuum effects at the graphenematrix interface [10]. A fundamental understanding of the relationship between thermal properties and interfacial optimization is of great significance in this research
area, which will eventually lead to the development of fundamentally new material systems. Recent efforts on surface functionalization, intrinsic defects or vacancies, edge passivation, doping or substitution, and grain-boundaries
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