An Atomistic Carbide-Derived Carbon Model Generated Using ReaxFF-Based Quenched Molecular Dynamics

Abstract

Abstract:We report a novel atomistic model of carbide-derived carbons (CDCs), which are nanoporous carbons with high specific surface areas, synthesis-dependent degrees of graphitization, and well-ordered, tunable porosities. These properties make CDCs viable substrates in several energy-relevant applications, such as gas storage media, electrochemical capacitors, and catalytic supports. These materials are heterogenous, non-ideal structures and include several important parameters that govern their performance. Therefore, a realistic model of the CDC structure is needed in order to study these systems and their nanoscale and macroscale properties with molecular simulation. We report the use of the ReaxFF reactive force field in a quenched molecular dynamics routine to generate atomistic CDC models. The pair distribution function, pore size distribution, and adsorptive properties of this model are reported and corroborated with experimental data. Simulations demonstrate that compressing the system after quenching changes the pore size distribution to better match the experimental target. Ring size distributions of this model demonstrate the prevalence of non-hexagonal carbon rings in CDCs. These effects may contrast the properties of CDCs against those of activated carbons with similar pore size distributions and explain higher energy densities of CDC-based supercapacitors.

Adsorption separation of heavier isotope gases in subnanometer carbon pores

“…The cryogenic adsorption separation demonstrates that S > 60 in the initial stage of adsorption (~1 min) arises from the selective adsorption of 18 O 2 in the narrow sites of the pores (<0.4 nm) present in the CDC structure 32 . In our previous work, atomistic models of CDCs were generated via molecular dynamics simulation and validated by experimental adsorption measurements 33 .…”

Mechanical Properties of Soot Particles: The Impact of Crosslinked Polycyclic Aromatic Hydrocarbons

“…This process has been adopted only to obtain starting geometries with varying degrees of crosslinking. This scheme allows structures to be rapidly formed through an unphysical scheme that provides a suitable geometry matching an experimental system (Thompson et al, 2017). Moreover, such a procedure requires rapid heat removal and therefore strongly coupled thermostats were used, such as the Berendsen thermostat (Ranganathan et al, 2017).…”

Wide-angle X-ray scattering combined with pair distribution function analysis of pyrolyzed wood

“…While the small-box modeling presented in this paper is sufficient for fast and simple comparison of the hard carbon structures, scrupulous readers may be interested in more quantitative analysis. Numerous publications report a largebox modeling using explicit shape functions of the layered structures (Thompson et al, 2017;Nishihara et al, 2018;Smith et al, 2004;Castro-Marcano et al, 2012).…”