Structural prediction of graphitization and porosity in carbide-derived carbons

Tomás, Carla de; Suarez-Martinez, Irène; Vallejos-Burgos, Fernando; López, M. J.; Kaneko, Katsumi; Marks, Nigel A.

doi:10.1016/j.carbon.2017.04.004

Cited by 73 publications

(72 citation statements)

References 59 publications

(112 reference statements)

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“…Comparisons were made to an experimental carbide-derived carbon (CDC) material with similar structural properties. These models that use ReaxFF and employ a post-quenching compression step provide clear improvement upon prior CDC models generated using QMD in terms of local bonding and pore size distribution and also closely match those recently published using a process involving removal of metal atoms from a carbide and subsequent annealing [65].…”

Section: Discussionsupporting

confidence: 67%

“…Qualitative visual observations do not show any alterations of ring bonding. Thus, the combination of ReaxFF with a post-compression step results in pore size distributions that more closely match experiments as well as a recent study that generated CDCs using the EDIP force field and, rather than QMD, annealing of a system after removal of metal atoms from a carbide lattice [65]. Specifically, this compression step combines properties of QMD-generated models at different quench rates: the local bonding structure is dominated by six-membered rings, but the pore size distribution does not largely extend in the mesoporous regime.…”

Section: Qmd-generated Cdc Structuressupporting

confidence: 75%

“…Previous QMD results have used force fields such as the Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) [61], the Environment-Dependent Interatomic Potential (EDIP) [62], the Reactive Summation State (RSS) [53], and the Tersoff potential [63] to generate nanoporous carbon structures for use in molecular simulation. While many impactful studies [49,52,54,55,[64][65][66] have been done with these forcefields, the generated structures have often failed to accurately reproduce experimental pore size distributions and always depend, at least in part, on the accuracy of the force field itself. Carbon-based materials, and CDCs in particular, present a unique challenge for these forcefields because of their nanoscale heterogeneity.…”

Section: Introductionmentioning

confidence: 99%

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

Thompson

Dyatkin

Wang

et al. 2017

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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.

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Section: Discussionsupporting

confidence: 67%

Section: Qmd-generated Cdc Structuressupporting

confidence: 75%

Section: Introductionmentioning

confidence: 99%

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

Thompson

Dyatkin

Wang

et al. 2017

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“…Another convincing example showing a good agreement between TEM images and atomistic modelling of the structure for non-graphitising carbons is presented in Figure 27. It is clear that these models proposed by Tomas et al [60], optimized using an annealing based molecular dynamics approach, reproduce the main characteristics of HRTEM pictures including microstructure, porosity at the nanometre scale, and graphitisation with increasing temperature. Simultaneously, the authors showed that they reproduce features of the experimental pair distribution functions derived from XRD data [60].…”

Section: Glass-like Carbon and Other Pyrolysed Non-graphitising Carbonsmentioning

confidence: 97%

“…The issue of the sp 3 -bonds' presence in non-graphitising carbons has not been completely explained. Most recent studies using the total scattering method combined with computer simulations of the atomic structure support the thesis that these carbons contain mostly sp 2 -type bonds; however, the presence of small amounts of sp 3 bonds is possible [26,60]. It should be mentioned that so far, the TEM investigations have not provided images of diamond-like structures in non-graphitising carbons and observations of isolated sp 3 bonds would be extremely difficult.…”

Section: Glass-like Carbon and Other Pyrolysed Non-graphitising Carbonsmentioning

confidence: 99%

Structure of Carbon Materials Explored by Local Transmission Electron Microscopy and Global Powder Diffraction Probes

Jurkiewicz

Pawlyta

Burian

2018

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Transmission electron microscopy and neutron or X-ray diffraction are powerful techniques available today for characterization of the structure of various carbon materials at nano and atomic levels. They provide complementary information but each one has advantages and limitations. Powder X-ray or neutron diffraction measurements provide structural information representative for the whole volume of a material under probe but features of singular nano-objects cannot be identified. Transmission electron microscopy, in turn, is able to probe single nanoscale objects. In this review, it is demonstrated how transmission electron microscopy and powder X-ray and neutron diffraction methods complement each other by providing consistent structural models for different types of carbons such as carbon blacks, glass-like carbons, graphene, nanotubes, nanodiamonds, and nanoonions.

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Cluster Fragments in Amorphous Phosphorus and their Evolution under Pressure

2021

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such as "ab initio" molecular dynamics (AIMD). ML-based interatomic potentials, therefore, are beginning to be applied to a range of challenging materials-science research questions, such as the modeling of phase-change memory materials, [12][13][14] catalysts, [15] or battery materials. [16] Recently, a number of "general-purpose" ML potentials have been reported, which can accurately describe a broad range of atomic configurations and materials properties-including silicon, [17] carbon, [18] aluminum, [19,20] and the binary Ga-As system. [21] The hope for such potentials is to enable "off-the-shelf" use without further modification: for example, the aforementioned silicon ML potential has been used to study complex structural transitions under pressure [22] or unusual mechanical properties of amorphous silicon (a-Si). [23] The starting point for the present study is a general-purpose Gaussian approximation potential (GAP) ML model for bulk and nanostructured phosphorus-which was shown to be flexible enough to be applicable to the pressure-induced liquidliquid phase transition from the molecular fluid to the network liquid, whilst also accurately describing the crystalline allotropes and the layered structure of phosphorene. [24] This GAP is now set to facilitate even more challenging studies on more extended length or time scales, and the exploration of other structurally complex phases for which it has not been explicitly "trained", such as amorphous phosphorus (a-P).Research interest in a-P has grown because of emerging applications in batteries. [25][26][27][28] As a commercially available anode material, red phosphorus provides a large cation-storage ability with high theoretical capacities by forming binary X-P compounds (X = Li, Na, K), but it suffers from low conductivity and a large volumetric change during cycling. [29] As discussed in ref. [30], these issues can be ameliorated by creating composites of a-P and carbonaceous materials: on the one hand, increasing electronic conductivity; [31,32] on the other hand, minimizing the mechanical stress induced by volume changes. [30,33] The structure and properties of phosphorus itself are clearly important for battery applications: for example, experimental work showed that the size of a-P particles in phosphoruscarbon composite anodes has an effect on the electrochemical performance, [34] and in situ transmission electron microscopy (TEM) revealed images of red phosphorus segments within a carbon nanofiber. [35] Computationally, structurally ordered phases have been studied with density-functional theory (DFT; Amorphous phosphorus (a-P) has long attracted interest because of its complex atomic structure, and more recently as an anode material for batteries. However, accurately describing and understanding a-P at the atomistic level remains a challenge. Here, it is shown that large-scale molecular-dynamics simulations, enabled by a machine-learning (ML)-based interatomic potential for phosphorus, can give new insights into the atomic structure of a-P and how...

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Structural prediction of graphitization and porosity in carbide-derived carbons

Cited by 73 publications

References 59 publications

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

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

Structure of Carbon Materials Explored by Local Transmission Electron Microscopy and Global Powder Diffraction Probes

Cluster Fragments in Amorphous Phosphorus and their Evolution under Pressure

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