The adsorption and gas separation properties of amorphous porous chalcogenides such as GeS2 are investigated using statistical mechanics molecular simulation. Using a realistic molecular model of such amorphous adsorbents, we show that they can be used efficiently to separate different gases relevant to environmental and energy applications (H-2, CO2, CH4, N-2). In addition to shedding light on the microscopic adsorption mechanisms, we show that coadsorption in this novel class of porous materials can be described using the ideal adsorbed solution theory (IAST). Such a simple thermodynamic model, which allows avoiding complex coadsorption measurements, describes the adsorption of mixture from pure component adsorption isotherms. Our results, which are found to be in good agreement with available experimental data, paves the way for the design of gas separation membranes using the large family of porous chalcogenides.

VL - 18 UR - http://xlink.rsc.org/?DOI=C6CP00467A IS - 19 JO - Phys. Chem. Chem. Phys. ER - TY - BOOK T1 - Springer Series in Materials ScienceMolecular Dynamics Simulations of Disordered MaterialsFirst-Principles Modeling of Binary Chalcogenides: Recent Accomplishments and New Achievements Y1 - 2015 A1 - Bouzid, A. A1 - Le Roux, S. A1 - Guido Ori A1 - Tugene, Christine A1 - Boero, M. A1 - Carlo Massobrio ED - Carlo Massobrio ED - Du, Jincheng ED - Bernasconi, Marco ED - Salmon, Philip S. AB -This contribution is focussed on a set of first-principles molecular dynamics results obtained over the past fifteen years for disordered chalcogenides. In the first part, we sketch and review the historical premises underlying research efforts devoted to the understanding of structural properties in liquid and glassy GexSe1-x systems. We stress the importance of selecting well performing exchange-correlation functionals (within density functional theory) to achieve a correct description of short and intermediate range order. In the second part, we provide a specific, comparative example of structural analysis for chalcogenide GeX4 systems differing by the chemical identity of the X atom. We are able to demonstrate that the correct account of differences between the coordination environments of the two corresponding glasses requires system sizes substantially larger than similar to 100 atoms.

PB - Springer International Publishing CY - Cham VL - 215 SN - 978-3-319-15674-3 UR - http://link.springer.com/10.1007/978-3-319-15675-0 ER - TY - BOOK T1 - Springer Series in Materials ScienceMolecular Dynamics Simulations of Disordered MaterialsMolecular Modeling of Glassy Surfaces Y1 - 2015 A1 - Guido Ori A1 - Carlo Massobrio A1 - Bouzid, A. A1 - Benoit A. Coasne ED - Carlo Massobrio ED - Du, Jincheng ED - Bernasconi, Marco ED - Salmon, Philip S. AB -Progress in computational materials science has allowed the development of realistic models for a wide range of materials including both crystalline and glassy solids. In recent years, with the growing interest in nanoparticles and porous materials, more attention has been devoted to the design of realistic models of glassy surfaces and finely divided materials. The structural disorder in glassy surfaces, however, poses a major challenge which consists of describing such surfaces using computer simulations. In this paper, we show how atomic-scale simulations can be used to develop and investigate the properties of glassy surfaces. We illustrate how both first principles calculations and classical molecular mechanics can be used to follow the trajectory at finite temperature of these systems, and obtain statistical thermodynamic averages to compare against available experiments. Both glassy oxide (silica) and non-oxide (chalcogenide) surfaces are considered.

PB - Springer International Publishing CY - Cham VL - 215 SN - 978-3-319-15674-3 UR - http://link.springer.com/10.1007/978-3-319-15675-0 ER - TY - JOUR T1 - Structure and Dynamics of Ionic Liquids Confined in Amorphous Porous Chalcogenides JF - Langmuir Y1 - 2015 A1 - Guido Ori A1 - Carlo Massobrio A1 - Pradel, Annie A1 - Ribes, Michel A1 - Benoit A. Coasne AB -Besides the abundant literature on ionic liquids in porous silica and carbon, the confinement of such intriguing liquids in porous chalcogenides has received very little attention. Here, molecular simulation is employed to study the structural and dynamical properties of a typical ionic liquid confined in a realistic molecular model of amorphous chalcogenide with various pore sizes and surface chemistries. Using molecular dynamics in the isobaric–isothermal (NPT) ensemble, we consider confinement conditions relevant to real samples. Both the structure and self-dynamics of the confined phase are found to depend on the *surface*-to-*volume* ratio of the host confining material. Consequently, most properties of the confined ionic liquid can be written as a linear combination of surface and bulk-like contributions, arising from the ions in contact with the surface and the ions in the pore center, respectively. On the other hand, collective dynamical properties such as the ionic conductivity remain close to their bulk counterpart and almost insensitive to pore size and surface chemistry. These results, which are in fair agreement with available experimental data, provide a basis for the development of novel applications using hybrid organic–inorganic solids consisting of ionic liquids confined in porous chalcogenides.

First-principles calculations within the framework of the density functional theory are used to construct realistic models for the surface of glassy

The structure of glassy GeS2 is studied in the framework of density functional theory, by using a fully self-consistent first-principles molecular dynamics (FPMD) scheme. A comparative analysis is performed with previous molecular dynamics data obtained within the Harris functional (HFMD) total energy approach. The calculated total neutron structure factor exhibits an unprecedented agreement with the experimental counterpart. In particular, the height of the first sharp diffraction peak (FSDP) improves considerably upon the HFMD results. Both the Ge and the S subnetworks are affected by a consistent number of miscoordinations, coexisting with the main tetrahedral structural motif. Glassy GeS2 features a short-range order quite similar to the one found in glassy GeSe2, a notable exception being the larger number of edge-sharing connections. An electronic structure localization analysis, based on the Wannier functions formalism, provides evidence of a more enhanced ionic character in glassy GeS2 when compared to glassy GeS2.

VL - 88 ER -