• Login
    View Item 
    •   DSpace@RPI Home
    • Rensselaer Libraries
    • RPI Theses Online (Complete)
    • View Item
    •   DSpace@RPI Home
    • Rensselaer Libraries
    • RPI Theses Online (Complete)
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Synthesis, structure and properties of hierarchical nanostructured porous materials studied by molecular dynamics simulations

    Author
    Chae, Kisung
    View/Open
    176048_Chae_rpi_0185E_10622.pdf (9.611Mb)
    Other Contributors
    Huang, Liping; Shi, Yunfeng; Meunier, Vincent; Garde, Shekhar;
    Date Issued
    2015-05
    Subject
    Materials engineering
    Degree
    PhD;
    Terms of Use
    This electronic version is a licensed copy owned by Rensselaer Polytechnic Institute, Troy, NY. Copyright of original work retained by author.;
    Metadata
    Show full item record
    URI
    https://hdl.handle.net/20.500.13015/1487
    Abstract
    A complete feedback loop among synthesis, structure and properties will help identify the proper synthesis parameters to design the optimal porous structures for a particular application. This will speed up the applications of HNPMs in many fields, such as electrodes for supercapacitors, lithium ion batteries and fuel cells, catalyst supports, materials for gas sensing and hydrogen storage, etc.; We first developed a unique computational nanocasting approach in MD to mimic the synthesis of HNPCs with both mesopores from the templating and micropores from the direct quench of carbon source in MD. Mesoporous structure such as the pore size and the pore wall roughness as well as the microporous structure such as the density and the graphitic pore walls can be independently controlled by synthesis parameters, such as the size of the template, the interaction strength between the template and carbon source, the initial carbon density and the quench rate, respectively.; For applications of porous materials in many fields of technological importance, such as catalysis, filtration, separation, energy storage and conversion, the efficiency is often limited by chemical kinetics, and/or diffusion of reactants and products to and from the active sites. Hierarchical nanostructured porous materials (HNPMs) that possess both mesopores (2 nm < pore size < 50 nm) and micropores (pore size < 2 nm) have shown great potential for these applications as their bimodal porous structure can provide highly efficient mass transport through mesopores and high electrochemically accessible surface area from micropores. Despite extensive experimental studies, it remains a great challenge to quantify the synthesis-structure-properties relations in HNPMs due to the limitations of existing characterization tools and the difficulty in separating the sum of many effects in experiments. In this thesis work, we carried out a detailed study on the synthesis-structure-property relations in hierarchical nanostructured porous carbons (HNPCs) by using classical molecular dynamics (MD) simulations.; These atomic models allowed us to quantify the structure-mechanical properties relation in aligned carbon nanotubes/amorphous porous carbon nanocomposites. Our study shows that there is an optimum balance between the crystallinity of CNTs and the number bridging bonds between CNTs and the microporous matrix in order for the nanocomposites to have desired mechanical properties such as high stiffness and high buckling resistance under compressive loading.; We further used these models to study the effects of the mesopore size and the pore wall roughness on the transport behaviors of methane in HNPCs. Our study shows that some defects in the mesopore walls do not have a significant effect on transport properties, especially in large channels. However, when the walls of small channels become rough, adsorption and transport behaviors change dramatically. Our study shows that the enhanced flow in CNTs observed in experiments is mainly due to the smooth potential energy surface of CNTs with high quality of graphitic walls.; In order to carry out a systematic study on pressure-driven gas transport in HNPCs, a computationally efficient reflecting particle method (RPM) together with a perturbation-relaxation loop was developed in this work to make the pressure drop consistent for various structures and transport conditions. The mimetic nanocasting technique and the RPM method can be easily extended to study the synthesis-structure-transport properties relations in many other HNPMs.;
    Description
    May 2015; School of Engineering
    Department
    Dept. of Materials Science and Engineering;
    Publisher
    Rensselaer Polytechnic Institute, Troy, NY
    Relationships
    Rensselaer Theses and Dissertations Online Collection;
    Access
    Restricted to current Rensselaer faculty, staff and students. Access inquiries may be directed to the Rensselaer Libraries.;
    Collections
    • RPI Theses Online (Complete)

    Browse

    All of DSpace@RPICommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

    My Account

    Login

    DSpace software copyright © 2002-2022  DuraSpace
    Contact Us | Send Feedback
    DSpace Express is a service operated by 
    Atmire NV