Browsing by Author "Batteas, James"

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Collaborative Research: Understanding and Tuning the Molecular Arrangement and Charge Storage Properties of Textured Graphene-Ionic Liquid Interface
Chemistry; TAMU; https://hdl.handle.net/20.500.14641/223; National Science Foundation
Non-technical summary With the ever-increasing need for electrical power on demand, next generation energy storage devices (batteries and supercapacitors) must be designed that can support higher energy densities than current technologies. Therefore, new electrolyte and electrode materials must be explored that allow for higher electrolyte packing densities. To improve electrode/electrolyte interfaces, this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, seeks to understand how the structure of ionic liquids and their arrangement at electrode interfaces may be tuned by precisely controlling electrode geometry on the nanoscale. Single-layer graphene, a carbon-based material, just one-atom thick, which can function as a conductive electrode that is highly flexible, is used to created textured electrodes for this study. The research team investigates the influence of the electrode morphology on the organization of the ionic liquid electrolyte and how it impacts charge storage. In addition to exploring these fundamental science questions, this project supports the education and training of undergraduate and graduate students from diverse backgrounds, at the intersection of materials and surface science, contributing to the development of the energy sector work force in the U.S., by training students in cross-cutting research in a coordinated collaborative environment between the labs of the principle investigators at UIUC and TAMU. Technical summary With this grant, supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, the principle investigators (Espinosa-Marzal at UIUC and Batteas at TAMU) test the fundamental hypothesis that by controlling surface morphology and substrate-induced charge doping, along with the chemical composition of the ionic liquids, the local packing density of the liquid on graphene can be precisely modulated. This in turn is expected to afford better control over their charge storage properties. To fill the outlined knowledge gap, the team pursues three major lines of research. New methods to prepare graphene surfaces with precisely controlled charge doping and morphology from the atomic to the nanoscale are developed. In addition, the effects of substrate morphology and charge doping on the interfacial structure of ionic liquids and on the characteristics of the electrical double layer are investigated by Atomic Force Microscopy in an electrochemical cell. Furthermore, local and global electrochemical impedance spectroscopy are used to relate the electrical double layer to the differential capacitance of the textured interfaces. These studies allow determining the relative contributions of graphene roughness, charge doping and ionic liquid composition on the electrical double layer and its capacitance. The knowledge gained from this project is expected to enable control of the interfacial assembly of the liquids and stored charge through the modulation of the graphene texture. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
Collaborative Research: Understanding and Tuning the Molecular Arrangement and Charge Storage Properties of Textured Graphene-Ionic Liquid Interface
Chemistry; TAMU; https://hdl.handle.net/20.500.14641/606; National Science Foundation
Non-technical summary With the ever-increasing need for electrical power on demand, next generation energy storage devices (batteries and supercapacitors) must be designed that can support higher energy densities than current technologies. Therefore, new electrolyte and electrode materials must be explored that allow for higher electrolyte packing densities. To improve electrode/electrolyte interfaces, this project, supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, seeks to understand how the structure of ionic liquids and their arrangement at electrode interfaces may be tuned by precisely controlling electrode geometry on the nanoscale. Single-layer graphene, a carbon-based material, just one-atom thick, which can function as a conductive electrode that is highly flexible, is used to created textured electrodes for this study. The research team investigates the influence of the electrode morphology on the organization of the ionic liquid electrolyte and how it impacts charge storage. In addition to exploring these fundamental science questions, this project supports the education and training of undergraduate and graduate students from diverse backgrounds, at the intersection of materials and surface science, contributing to the development of the energy sector work force in the U.S., by training students in cross-cutting research in a coordinated collaborative environment between the labs of the principle investigators at UIUC and TAMU. Technical summary With this grant, supported by the Solid State and Materials Chemistry program in the Division of Materials Research at NSF, the principle investigators (Espinosa-Marzal at UIUC and Batteas at TAMU) test the fundamental hypothesis that by controlling surface morphology and substrate-induced charge doping, along with the chemical composition of the ionic liquids, the local packing density of the liquid on graphene can be precisely modulated. This in turn is expected to afford better control over their charge storage properties. To fill the outlined knowledge gap, the team pursues three major lines of research. New methods to prepare graphene surfaces with precisely controlled charge doping and morphology from the atomic to the nanoscale are developed. In addition, the effects of substrate morphology and charge doping on the interfacial structure of ionic liquids and on the characteristics of the electrical double layer are investigated by Atomic Force Microscopy in an electrochemical cell. Furthermore, local and global electrochemical impedance spectroscopy are used to relate the electrical double layer to the differential capacitance of the textured interfaces. These studies allow determining the relative contributions of graphene roughness, charge doping and ionic liquid composition on the electrical double layer and its capacitance. The knowledge gained from this project is expected to enable control of the interfacial assembly of the liquids and stored charge through the modulation of the graphene texture. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
Collaborative Research: Directing Charge Transport in Hierarchical Molecular Assemblies
Chemistry; TAMU; https://hdl.handle.net/20.500.14641/606; National Science Foundation
In this project funded by the Macromolecular, Supramolecular and Nanochemistry program of the Chemistry Division, Professor James Batteas of the Texas A & M University and Professor Charles Drain of Hunter College of the City University of New York study the molecular assembly and electron transport properties of molecules that might help in electronic device miniaturization. Moore's Law, which has held for the last four decades, states that the density of transistors on an electronic device "chip" will double approximately every two years, making electronic devices smaller, faster and more powerful. A pressing question is whether Moore's Law will continue into the future or has it reached its fundamental limits. Professors Batteas and Drain study metal-organic complexes known as porphyrinoids, found in nature as the active component of hemoglobin and chlorophyll, to aid in these developments. They design, synthesize and evaluate the conductive properties of porphyrinoids assembled into specific structures on surfaces. Using imaging techniques such as atomic force microscopy (AFM) and scanning tunneling microscopy (STM), the team can place individual molecules into precise arrangements on surfaces and measure not only their assembled structure at the molecular level but also how the structure controls the movement of electrons through the molecules. This research has broader impacts in science and technology, and enables the rational design of potential molecular electronic devices, including enhanced photovoltaics, chemical sensors and molecular electronics. The team also trains students, for broader impacts in education, in fundamental materials chemistry, preparing them for the 21st century high technology jobs sector. Professor Batteas and Professor Drain study how to design, synthesize and evaluate the conductive properties of porphyrinoids assembled on metal surfaces with an eye toward the implementation of hybrid molecular-based devices for photonics applications, including enhanced photovoltaics, chemical sensors and molecular based electronics. The electroactive properties and self-assembly of robust porphyrinoids can be readily tuned through chemical synthesis using simple high yield reactions that facilitate commercial viability, making them attractive targets to be integrated as active components in electronic devices. In this project porphryinoids are assembled on Au surfaces in precise architectures via a combination of nanolithography and directed click-chemical reactions to create nanoscopic assemblies of less than 10 nm in lateral dimension. Characterization methods (time resolved florescence, UV-visible absorption, STM and AFM) are applied to understand how local molecular interactions influence electron transport properties in small molecule assemblies, how spatial confinement of molecules on a surface influence their resulting assembly process and the structures that can be formed, and how the assembled architectures control electron transport. Broader impacts of the research result in an improved fundamental understanding of the assembly and electron transport properties of the porphryiods, with potential to influence molecular electronic device and solar light harvesting applications. Broader impacts through education and outreach incorporate aspects of the work, including atomic scale imaging, nanolithography, molecular self-assembly and nanoscale electronics, into demonstrations for elementary school students as part of a weeklong summer camp on Nanotechnology (at Texas A&M University), and into the undergraduate and graduate classrooms at Texas A&M University and CUNY Hunter College.