Elucidating the Thermal Properties of Partially Chlorinated Graphene Using Molecular Dynamics Simulations

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Graphene exhibits excellent thermal properties, making it attractive for thermal management applications.
• Chlorination is a common method to functionalize graphene, potentially altering its properties.
• Understanding thermal transport in functionalized graphene is crucial for designing advanced materials.

Purpose of the Study:

• To investigate the impact of partial chlorination on the thermal transport properties of graphene.
• To develop and validate a hybrid force field (h-FF) for simulating chlorinated graphene.
• To quantify the reduction in thermal conductivity as a function of chlorine content.

Main Methods:

• Molecular dynamics (MD) simulations utilizing a novel hybrid force field (h-FF).
• The h-FF incorporates Tersoff, Morse, and Lennard-Jones potentials, with atomic charge equilibration.
• Density functional theory (DFT) was used for h-FF calibration, focusing on binding energies and bond lengths.

Main Results:

• Partially chlorinated graphene (PCG) sheets were found to be thermally stable at 300 K with up to 25% chlorine content.
• Simulations showed flattened optical phonon modes and downshifted acoustic modes in PCG due to enhanced phonon scattering.
• Thermal conductivity decreased significantly with increasing chlorine content, dropping by ~70% at ~1% Cl and ~98% at ~25% Cl.

Conclusions:

• The developed h-FF accurately predicts the thermal behavior of chlorinated graphene.
• Partial chlorination drastically reduces thermal conductivity in graphene, offering a pathway to tune thermal properties.
• These findings provide critical insights for designing graphene-based materials for specific thermal management applications.