Investigation of the effect of iron nanoparticles on n-dodecane combustion under external electrostatic fields

Kritikos, Efstratios; Giusti, Andrea

doi:10.1016/j.proci.2022.07.003

Cited by 6 publications

(9 citation statements)

References 42 publications

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“…MD simulations are performed using an amorphous FeNP, consisting of 2741 atoms, surrounded by 400 oxygen molecules. The preparation procedure of the FeNP is similar to the one reported in ref 48. The annealing process and the overall preparation of the FeNP for the oxidation simulations are discussed in detail in Section S1 of the Supporting Information.…”

Section: Reactive Molecular Dynamicsmentioning

confidence: 99%

“…The oxide shell thickness of the FeNP is measured from the individual absorbed oxygen atoms. 48 Specifically, the distance is measured between each absorbed oxygen and the nearest point of the FeNP's surface. The FeNP surface is constructed using the OVITO software 97 based on the alpha-shape method.…”

Section: Nudged Elastic Band Analysismentioning

confidence: 99%

“…On the other hand, the QTPIE method can describe with good accuracy the electrostatic behavior of the conductive FeNP. The capability of the QTPIE method with the ReaxFF-2016 parameter set to predict induced polarization of a face-centered cubic (FCC) FeNP is demonstrated in Section S2, while for a BCC FeNP it has been assessed in ref 48.…”

Section: Charge Distribution and Induced Polarizationmentioning

confidence: 99%

“…45−47 In a recent study by the authors of the present work, the external electric field effects on the combustion of n-dodecane with FeNPs as an additive were also investigated. 48 Results showed a strong catalytic effect of FeNPs on the combustion of ndodecane and suggested that the oxidation process of both the hydrocarbon fuel and the nanoparticle can to some extent be manipulated via electric fields. In that study, a charge equilibration method able to shield long-range charge transfers was used.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Iron Nanoparticle Oxidation under External Electrostatic Fields Using Reactive Molecular Dynamics

Kritikos,

Giusti

2024

J. Phys. Chem. C

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A reactive molecular dynamics (MD) study of iron nanoparticle oxidation under externally applied electrostatic fields is performed, with a focus on the role of charge transfers and electrically induced polarization. Two charge equilibration methods that either enable or shield long-range charge transfers and two ReaxFF parameter sets that predict different bonded and nonbonded interactions are used in the evaluation. The field-induced polarization modeled in MD simulations is in good agreement with analytical solutions and density functional theory (DFT) computations. Results show that oriented external electric fields affect the transition states of reactions involved in oxygen adsorption on the nanoparticle surface and oxygen diffusion inside the iron lattice. The oxygen diffusion inside the nanoparticle can be either aided or hindered by the external electric field depending on the direction of motion of oxygen compared to the direction of the external electric field. Simulations also demonstrate that long-range charge transfers increase the reactivity of the system compared to shielded interactions. Regarding ambient conditions, a density increase can accelerate the kinetics of the system, while temperature variations have a smaller effect on the oxidation rate for the systems investigated here. The external electrostatic field affects the kinetic energy, collision frequency, and reactivity of the system. When charge transfers are limited to close interactions, the system's kinetics is accelerated only under strong external electric fields. On the contrary, if long-range charge transfers are enabled, an increase in the oxidation rate is observed for weak electric fields, whereas for stronger electric fields the oxidation rate decreases due to a more coherent movement of the charged particles under the Lorentz forces. In addition, external electric fields affect the chemical composition of iron and iron oxide nanoparticles. The diffusion of the negatively charged absorbed oxygen atoms toward one side of the nanoparticle causes an anisotropic thickness of the oxidation layer. The influence of the external electric field on the system's kinetics depends on the choice of the ReaxFF parameter set, highlighting the importance of accurate training of the force field with a focus on charge transfers and their distribution under external fields. These findings provide insight into the fundamental effects of charge transfers and field-induced polarization on the oxidation process of a nanoparticle in the presence of an external electrostatic field and offer a comprehensive evaluation of the capability of the MD-ReaxFF framework to predict the underlying physical mechanisms at the atomistic scale.

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Section: Reactive Molecular Dynamicsmentioning

confidence: 99%

Section: Nudged Elastic Band Analysismentioning

confidence: 99%

Section: Charge Distribution and Induced Polarizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of Iron Nanoparticle Oxidation under External Electrostatic Fields Using Reactive Molecular Dynamics

Kritikos,

Giusti

2024

J. Phys. Chem. C

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“…In this context, reactive molecular dynamics (MD) simulations enabled by reactive force fields (ReaxFFs) have proven their ability to provide fundamental insights into the oxidation of gas, liquid, and solid fuels, predicting material properties and other physicochemical processes . For the specific case of iron, (reactive) molecular dynamics simulations have been used for various applications: to determine the material properties of pure liquid iron, the oxidation of nanoparticles and surfaces with oxygen, − the oxidation of Fe with CO 2 , and H 2 O, and also for the oxidation of alloys . In the study of Thijs et al reactive MD simulations were used to investigate the thermal and mass accommodation coefficients (TAC and MAC, respectively) for the combination of high-temperature iron(-oxide) and air.…”

Section: Introductionmentioning

confidence: 99%

Effect of Fe–O ReaxFF on Liquid Iron Oxide Properties Derived from Reactive Molecular Dynamics

Thijs,

Kritikos,

Giusti

et al. 2023

J. Phys. Chem. A

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As iron powder nowadays attracts research attention as a carbon-free, circular energy carrier, molecular dynamics (MD) simulations can be used to better understand the mechanisms of liquid iron oxidation at elevated temperatures. However, prudence must be practiced in the selection of a reactive force field. This work investigates the influence of currently available reactive force fields (ReaxFFs) on a number of properties of the liquid iron–oxygen (Fe–O) system derived (or resulting) from MD simulations. Liquid Fe–O systems are considered over a range of oxidation degrees Z O , which represents the molar ratio of O/(O + Fe), with 0 < Z O < 0.6 and at a constant temperature of 2000 K, which is representative of the combustion temperature of micrometric iron particles burning in air. The investigated properties include the minimum energy path, system structure, (im)miscibility, transport properties, and the mass and thermal accommodation coefficients. The properties are compared to experimental values and thermodynamic calculation results if available. Results show that there are significant differences in the properties obtained with MD using the various ReaxFF parameter sets. Based on the available experimental data and equilibrium calculation results, an improved ReaxFF is required to better capture the properties of a liquid Fe–O system.

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Reactive force field molecular dynamics (ReaxFF-MD) simulation of lignite combustion under an external electric field

Yu,

Lou,

et al. 2024

Fuel

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Investigation of the effect of iron nanoparticles on n-dodecane combustion under external electrostatic fields

Cited by 6 publications

References 42 publications

Investigation of Iron Nanoparticle Oxidation under External Electrostatic Fields Using Reactive Molecular Dynamics

Investigation of Iron Nanoparticle Oxidation under External Electrostatic Fields Using Reactive Molecular Dynamics

Effect of Fe–O ReaxFF on Liquid Iron Oxide Properties Derived from Reactive Molecular Dynamics

Reactive force field molecular dynamics (ReaxFF-MD) simulation of lignite combustion under an external electric field

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