Gennady Gor: Research

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The main focus of the Computational Laboratory for Porous Materials is nanoporous materials, solids with pores of 100 nanometers and below. Such materials play a significant role in both nature and technology. Synthetic nanoporous materials are employed in the chemical industry as adsorbents, catalysts and separation membranes, among other uses. Naturally occurring nanoporous materials include coal and shale, key fuels in the production of energy. Another research focus is soot agglomerates, which are not porous, but rather nanostructured materials with features on the same scale as nanoporous solids. We work on the wide spectrum of phenomena related to the interfaces between these nanoporous or nanostructured solids and fluids: fluids adsorption, fluids transport and the propagation of ultrasound in fluid-saturated porous media, to name a few. Our approaches are mainly theoretical; we use various modeling techniques to represent phenomena at the nanoscale: Monte Carlo simulations, molecular dynamics, density functional theory and finite element analysis.

The current projects are:

A brief description of each of the projects is given below.

Note for potential graduate and undergraduate researchers: we are always looking for strong candidates to join the group. The list of the possible projects is not limited to the ones above. Interested candidates should email to Dr. Gennady Gor with a short cover letter and a CV. Although most of the projects involve collaborations with experimental groups at NJIT and beyond, our research is purely theoretical and computational. Thus strong math skills is a necessary condition to join the group, programming experience is a plus.

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Elastic Properties of Confined Fluids

Compressibility of a fluid in a porous medium determines the response of the medium to mechanical loads, and acoustic waves propagation in particular. If the pores of the medium are in the nanometer range, many thermodynamic properties of the fluid confined in such pores are altered, and the fluid compressibility is not an exception. We study the compressibility of simple and complex fluids in confinement using molecular simulations and relate in order to predict the wave propagation in fluid-saturated nanoporous media.

This is how theoreticians view an experiment in which ultrasound is used to probe a porous body impregnated with fluid (Drawing by Alina Emelianova).

Publications: Maximov, M. A.; Gor, G. Y. "Molecular Simulations Shed Light on Potential Uses of Ultrasound in Nitrogen Adsorption Experiments", Langmuir 2018, 34(51), 15650-15657, DOI: 10.1021/acs.langmuir.8b02909.
Dobrzanski, C. D.; Maximov, M. A.; Gor, G. Y. "Effect of Pore Geometry on the Compressibility of a Confined Simple Fluid", J. Chem. Phys., 2018, 148, 054503, DOI: 10.1063/1.5008490, preprint is available at arXiv:1710.05220 [physics.chem-ph]
Gor, G. Y.; Gurevich, B. "Gassmann Theory Applies to Nanoporous Media", Geophys. Res. Lett., 2018, 45(1), 146-155, DOI: 10.1002/2017GL075321, preprint is available at arXiv:1710.05216 [physics.geo-ph]

Researchers: Chris Dobrzanski, Nick Corrente, Max Maximov Collaborators: Boris Gurevich, Patrick Huber

Morphological Changes of Atmospheric Black Carbon

Soot is a major environmental pollutant with impacts ranging from air quality and human health to climate. The extent of these impacts depends on the microstructure of soot nanoparticles and their surface properties. The soot microstructure is complex, with nanoparticles being fractal aggregates of graphitic spherules mixed with organic and inorganic combustion products or other atmospheric chemicals. On top of it, soot nanoparticles often change structure when interacting with chemicals adsorbed on their surface. The main goal of this project is to develop a molecular-based model for soot nanoparticles restructuring (Gor's group) and verify it against experimental measurements (Khalizov's group).
SEM micrographs of (a) fresh soot particle, (b) soot particle coated with anthracene, where original morphology is sustained, and (c) soot particle coated with phenanthrene, where the fractal particle collapsed into a globule. (From Dr. Alexei Khalizov, unpublished).

Publications: Chen, C.; Enekwizu, O. Y.; Fan, X.; Dobrzanski, C. D.; Ivanova, E. V.; Ma, Y.; Gor, G. Y.; Khalizov, A. F. "Single parameter for predicting the morphology of atmospheric black carbon", Environ. Sci. Technol., 2018, 52(24), 14169-14179, DOI: 10.1021/acs.est.8b04201

Researchers: Ogo Enekwizu (Khalizov's group), Elly Ivanova, Collaborators: Alexei Khalizov

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Adsorption-Induced Deformation of Nanoporous Materials

When a solid surface accommodates guest molecules, they induce noticeable stresses to the surface and cause its strain. Nanoporous materials have high surface area and, therefore, are very sensitive to this effect called adsorption-induced deformation. In recent years, there has been significant progress in both experimental and theoretical studies of this phenomenon, driven by the development of new materials as well as advanced experimental and modeling techniques. Also, adsorption-induced deformation has been found to manifest in numerous natural and engineering processes, e.g., drying of concrete, water-actuated movement of non-living plant tissues, change of permeation of zeolite membranes, swelling of coal and shale, etc. Our goal is to develop a quantitative molecular-based model for this phenomenon.

When a sponge absorbs fluid, it swells. When a nanoporous material adsorbs fluid, it can both expand or contract. In the case of zeolites, it is often contraction.

Publications: Yurikov, A.; Lebedev, M.; Gor, G. Y.; Gurevich, B. "Sorption-Induced Deformation and Elastic Weakening of Bentheim Sandstone", J. Geophys. Res. Solid Earth, 2018, 123(10), 8589-8601 DOI: 10.1029/2018JB016003
Balzer, C.; Waag, A. M.; Gehret, S.; Reichenauer, G.; Morak, R.; Ludescher, L.; Paris, O.; Putz, F.; Elsaesser, M.; Husing, N.; Bernstein, N.; Gor, G. Y.; Neimark, A. V. "Adsorption-induced deformation of hierarchically-structured mesoporous silica - effect of local anisotropy", Langmuir, 2017, 33 (22), p. 5592-5602, DOI: 10.1021/acs.langmuir.7b00468
Gor, G. Y.; Huber, P.; Bernstein, N. "Adsorption-Induced Deformation of Nanoporous Materials - a Review", Appl. Phys. Rev., 2017, 4, 011303, DOI: 10.1063/1.4975001

Researchers: Alina Emelianova, Lukas Ludescher, Andrei Kolesnikov Collaborators: Oskar Paris, Gudrun Reichenauer, Patrick Huber

New Methods for Characterization of Porous Materials

Porous materials have myriad of applications. Nowadays, materials are carefully tailored for each application. Materials scientists and chemist need precise tools for characterization of the synthesized samples, to determine the surface area, pore morphology, pore size distribution, etc. Gas adsorption has been utilized for this purpose. We develop theoretical models of gas adsorption in porous materials, as well as employ new phenomena for characterization purposes (such as ultrasound or adsorption-induced deformation).
SEM: Structure of silica colloidal crystals (synthetic opals).

Publications: Galukhin, A. V.; Bolmatenkov, D.; Emelianova, A.; Zharov, I.; Gor, G. Y., "Porous Structure of Silica Colloidal Crystals", Langmuir, 2019, DOI: 10.1021/acs.langmuir.8b03476

Researchers: Marcos Molina, Alina Emelianova, Max Maximov Collaborators: Andrey Galukhin, Ilya Zharov

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Molecular Modeling of Organophosphorous Compounds

Several organophosphorus compounds, such as G-agents sarin and soman have been synthesized during the World War II to be used as chemical warfare agents (CWA). Despite the 1993 Chemical Weapons Convention, that outlaws the production and use of chemical weapons and their precursors, the use of CWA by terrorists still remain a threat. Thus there is a need to develop processes for chemical protection, capture and decontamination of CWAs. These studies require knowledge of thermodynamic properties of CWAs, in particular quantitative predictions of phase equilibrium of CWA in the presence of adsorbents. Due to the extreme toxicity of CWAs, experiments with them are very limited, and many of the experiments are made with their less toxic simulants. We employ molecular simulations for both CWAs and simulants. Modeling data for simulants can be readily verified experimentally, and justify the use of modeling data for CWAs for predictions as an alternative to experiments.
Chemical structure of sarin and its most common simulant -- DMMP.

Researchers: Alina Emelianova, Elizaveta Basharova, Ella Ivanova, Evaristo Villaseco Arribas, Andrei Kolesnikov

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Molecular Simulation of Solvation and Softening of Polypropylene Battery Separators in Carbonate Solvents

Lithium-ion batteries (LIBs) is the leading solution for electrical energy storage, which provide the highest energy and power per unit mass. Although it is already a well-developed technology, it still has one weak point - safety. A lithium-ion battery failure may cause thermal runaway; and the battery can catch on fire. While the performance characteristics of the batteries (e.g. specific power or specific energy) are determined by the electrode materials, the battery safety relies on the separator. LIB separators are typically made of porous semicrystalline polypropylene. Recent experiments showed that, when polypropylene separators are immersed in carbonate solvents used in LIBs, the separators mechanical properties are significantly reduced. The extent of the observed reduction is unexpected, and the physical mechanism is unclear. We aim to elucidate this mechanism on the molecular level to provide a path towards the development of porous polymeric membranes with improved mechanical properties.
Structure of a lithium battery cell (left). Two challenging problems related to the properties of the separator: lithium intercalation into the electrode particles causes noticeable expansion of the anode particles. Expanding anode compresses the separator, decreasing the ion transport through its pores (center). Lithium dendrite can grow through the separator and cause short circuit (right).

Researchers: Marcos Molina, Ella Ivanova

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New Algorithms for VLE (Vapor-Liquid Equilibrium) Calculations

Phase equilibria, and vapor-liquid equilibrium in particular is of utmost importance for many chemical processes. The Holy Grail here is to be able to predict the phase equilibrium of pure species and mixtures knowing just their molecular structure. One of the general approaches to this problem is based on the so-called Monte Carlo molecular simulation. We are exploring new Monte Carlo methods for robust predictions of phase equilibria.
The name of the method, coined by Stanislaw Ulam, originates from a random number generator, which is inherent not just to this method but to casino as well. (Image from here)

Researchers: Max Maximov

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