Ahmed, S., Arabha, S., Gonzalez, R. I., & Rizvi, R. (2022). Interactions of Gas Particles with Graphene during High-Throughput Compressible Flow Exfoliation: A Molecular Dynamics Simulations Study. The Journal of Physical Chemistry C, 126(22), 9378-9385. https://doi.org/10.1021/acs.jpcc.2c00425

Abstract: The field of two-dimensional (2D) nanomaterials has gained significant interest over the last few decades in numerous applications because of their unique properties that exhibit when a bulk material is reduced to its 2D form. A wide variety of 2D layered materials are synthesized by a newly developed compressible flow exfoliation (CFE) process, which has considerable advantages over current top-down approaches. In this study, classical molecular dynamics (MD) simulations are used to investigate the interactions of gas particles with pristine, unfunctionalized graphene sheets during the CFE process and try to understand the atomistic mechanism of layer separation. The thermal vibration of graphene layers increases with the elevation of temperature that accelerates the exfoliation tendency, but the presence of static gas particles is insignificant here because of their lower binding energy. The range of one-directional flow velocities is incorporated to the compressible gases to replicate the experimental situation, and dispersion of graphene is observed when the velocity exceeds the supersonic flow condition. Analyzing the dynamic properties of exfoliation, it is established that sliding or the parallel direction is the preferable exfoliation mechanism of graphene than vertical separation. Besides, the upstream pressure plays a fundamental role because gas density and flow velocity are associated with that. It is also observed that heavier gas is less susceptible to delaminate graphene than lighter gas because of their higher atomic mass and lower flow rate at identical conditions. The findings of this study provide more flexibility to synthesize not only graphene but any 2D materials using compressible gases.