Date of Award
Spring 2024
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Chemical and Environmental Engineering (ENAS)
First Advisor
Pfefferle, Lisa
Abstract
Of late, the fundamental electronic properties of systems have been tuned using confinement, including strain tuning of bandgaps in 2D materials and inducing or altering magnetic and superconducting properties. The use of nanoscale materials intercalated into 2D confinement systems has tremendous potential for fabricating materials whose behavior is markedly different from that observed at the macroscale. Tuning nanoscale properties by means of varying confinement spacing and inducing superconductivity provides a route to designing application specific materials with further use in catalysis, solid state battery electrodes, optoelectronics and quantum sensing amongst other applications. However, the development of these technologies is hindered by the challenge of achieving materials with high critical temperatures (Tc) and processing these into devices. The graphene-based system utilized in this Dissertation is made of earth-abundant materials and can utilize of the significant amount of precedent work done on putting graphene into device formats. However, the pressure requirements for hydride-containing materials to become superconductive is over 100 GPa, which makes them impractical for utilitarian applications. Therefore, using 2D materials for superconductivity through inducing strain in a confined system may lower the pressure required for intercalated moieties to become high-temperature superconductors. 2D confinement systems are useful for providing induced pressure by intercalating nanoparticles larger than the spacing between the layers of the system. Hence, this dissertation aims to unravel gaps in our comprehension of twodimensional confined systems for generating and retaining magnetism and superconductivity following depressurization from ultra-high pressures. My dissertation was initially motivated by DFT calculations of a collaborator, which showed the feasibility of intercalating H2S between graphene layers and the capability to engineer the interlayer spacing by functionalizing graphene with a dithiol linker of variable length. I employed various experimental and characterization techniques to study how reaction conditions and organic dithiol linkers can cause variable, reproducible spacings between graphene oxide to create confinement systems. I determined the conditions under which the spacing can be adjusted by the type of linker used, the concentration of the linker, and the reaction conditions. By employing dithiol linkers of different lengths, such as three (TPDT) and four (QPDT) aromatic rings, I was able to adjust the spacing between graphene oxide layers under varied reaction conditions. The results indicate that I was able to reproducibly control the spacing between graphene oxide layers from 0.37 nm to over 0.50 nm. After I created this confined graphene system of 2D materials, I studied the influence of pressure on confined nanoparticles, gases, including their material properties. I demonstrated that a strained graphene confinement system can retain properties of its confined species formed at high pressure. I aimed to evaluate the effect of intercalated cobalt particles on the magnetic properties of my linked graphene oxide system via strain and transient pressurization. This phenomenon occurs due to an induced pressure created by strain on the flexible 2D system caused by the intercalated cobalt nanoparticles confined between the linked graphene oxide layers and pressurized between 0 GPa and 25 GPa. After quenching to ambient pressure, each sample showed promising ferromagnetic behaviors, demonstrating that this confinement system can lock in phase changes created by transient high pressure in the GPa range. Lastly, I studied the superconducting properties of a nanoconfined system with palladium nanoparticles under pressure up to 25 GPa. The superconducting behavior of the Pd nanoparticles occurs and is retained at 5 GPa with a Tc of 2.3K and 5K at a lower temperature, i.e. 900˚C instead of 1100˚C. I demonstrated that high pressure properties can be retained after depressurization in the proposed confinement system with incorporated palladium nanoparticles. The induced pressure not only increases the Tc, but the properties are retained months after the pressurization is performed and, subsequently, pressure is released. The graphene-based confinement system and its transient pressurization presented in this dissertation offers a new platform or emergent high-temperature superconductive materials.
Recommended Citation
Sugak, Nikita, "Studying the Potential Superconductivity and Magnetism of Linked Graphene Oxide Nanosheets" (2024). Yale Graduate School of Arts and Sciences Dissertations. 1254.
https://elischolar.library.yale.edu/gsas_dissertations/1254
