Veronica Augustyn

The continuous need for the electrification of electronics and vehicles leads to significant demand for more powerful electrochemical energy storage devices including rechargeable batteries. In this context, it is necessary to develop new battery electrodes with properties that can supersede those of existing commercial devices while also diversifying the materials supply chain with new chemistries. The goal of this research is to discover new transition metal oxide materials for insertion-type batteries with high power and high energy. To accomplish this goal, the objective of this research is to (1) Synthesize and characterize shear-phase transition metal oxides of tungsten and niobium, (2) Perform electrochemical characterization of their ion-insertion behavior for protons (aqueous electrolyte) as well as cations (non-aqueous electrolytes), and (3) Characterize their optical and electronic structure changes during ion insertion. The outcome of this research will be the understanding of materials structure-electronic structure-electrochemical property correlations in shear-phase transition metal oxide electrodes that will yield advances in the design of materials for high power and high energy batteries

The goal of the proposed research is to investigate atomic-scale dynamics to rationalize thermal and mass transport as well as thermodynamics in superionic conductors. This will provide the critical understanding needed to enable thermal engineering based on superionics for novel energy-conversion technologies. Superionic conductors are rare solid materials with part-crystalline/part-liquid character, in which ions can diffuse with high mobilities, even comparable to water at room temperature. These systems are currently attracting intense interest because of promising applications in many energy-conversion technologies, ranging from solid-state electrolytes for safer rechargeable batteries, to efficient thermoelectric materials and solid-oxide fuel-cells. This project will investigate how the anharmonic atomic dynamics in superionic conductors impact thermal transport and thermodynamic stability, and enable fast ionic diffusion, by combining state-of-the-art experimental and computational modeling techniques. A targeted set of superionic compounds will be studied to extract systematic trends and new understandings. The project combines neutron and x-ray scattering experiments, thermodynamic and transport measurements, and computer simulations of atomic dynamics using first-principles and machine-learning methods, augmented with artificial intelligence.

The nanoconfinement of molecules and liquids is theorized to highly influence their properties and in turn, their chemical reactivity.1,2 Recent studies have investigated this concept by confining molecular or nanoparticle electrocatalysts within layered host structures,3������������������5 with the results indicating increased activity due to the nonconfined environment of the electrocatalyst. However, these studies have not elucidated whether the electrocatalytic reaction is actually occurring within the nanoconfined environment of the interlayer, or if the confined species are simply influencing the electronic structure or topology of the host structure. As a result, the experimental verification of how nanoconfinement influences chemical reactivity is scarce, likely due to the difficulty of synthesizing materials to control nanoconfinement, and the lack of adequate characterization techniques to determine the influence that this nanoconfined environment imparts on the chemical reactants. Layered and 2D materials such as Ni(OOH) and MoS2 are widely investigated as electrocatalysts for water splitting reactions,6,7 where the active sites are hypothesized to sit on the edges or surfaces of the layered structures (Figure 1, left). It is assumed that the ���������������bulk������������������ structure of these materials, including the interlayer, is inaccessible for the water splitting reactions, thus limiting the catalytic activity to the ���������������outer surface.������������������ However, layered and 2D materials are held together by weak van der Waals forces, leading some to consider this vacant space as an ���������������inner surface.������������������8 The weak interlayer bonding allows for tunability of the interlayer spacing using, for example, molecular pillars. This presents the tantalizing opportunity to utilize such materials to investigate chemical reactivity under nanoconfinement for processes such as chemical synthesis and electrocatalysis. In turn, the expanded interlayers will be ����������������activated��������������� for reactivity (Figure 1, right). The hypothesis driving this research is that molecular pillars can be used to open the interlayer of 2D materials for chemical reactions, and that the resulting nanoconfinement will result in enhanced reactivity due to frustration effects such as incomplete solvation. The technical approach of this proposed research is to investigate a model electrochemical reaction, the evolution of hydrogen in acidic electrolytes, under nanoconfinement by synthesizing a library of molybdenum disulfide (MoS2) materials with precise control of the interlayer spacing using molecular pillaring species. The dynamics of nanoconfined water in the molecularly-pillared MoS2 interlayers of various spacings will be probed with neutron scattering and solid state nuclear magnetic resonance (SSNMR). The mechanism of the hydrogen evolution reaction (HER) occurring on molecularly-pillared MoS2 electrocatalysts will be probed with electrochemical and in situ and operando spectroscopic and surface probe microscopy techniques. While the research will focus on a specific chemical reaction of interest for the hydrogen fuel cell community, the methodology and outcomes of this research will have influence beyond the HER and MoS2. It will provide experimental verification of how the geometry and surface chemistry of the nanoconfinement environment affect liquid phase chemical reactivity, and develop pathways to open the interlayer of 2D materials for chemical reactivity.

The objective of this proposal is to exploit an energetically inexpensive electrostatic charge transfer mechanism for the capture and release of CO2 in a reversible and controllable fashion at modified electrode surfaces. The coupling of electrochemical tools and concepts to chemical processes is emerging as a means to integrate renewable energy sources into chemical manufacturing and separations. Electrochemical methods also enable theoretical efficiencies that circumvent thermodynamic limitations posed by thermally-driven systems. Here, we propose an alternative electrochemical pathway that does not require redox processes for reversible capture and release. Our concept is based on capacitive, electrostatic charge transfer phenomena at an electrode surface, a yet unexplored concept that would dramatically decrease the energetic requirements for CO2 DAC.

The Center for Dielectrics and Piezoelectrics (CDP) is an internationally recognized research center dedicated to improving the science and technology of dielectric and piezoelectric materials and their integration into components and devices. This class of materials underpins the functionality of a broad array of electronic and electromechanical systems that are enabling for the transportation, energy, aerospace and defense, communications, and medical sectors of the economy. In response to the needs and opportunities for academic-focused research to support these technology areas, the CDP was established in 2013 as a joint center between North Carolina State University (NCSU) and The Pennsylvania State University (PSU) and became an official NSF I/UCRC in 2014. The center attracts companies across the supply chain from raw materials suppliers, to component/subsystems manufacturers, to test equipment suppliers, to device and systems integrators.

The overarching goal of this proposal is to understand the mechanisms of ion charge transfer and diffusion in solvated layered transition metal oxides for electrochemical energy storage. To attain this goal, the research objectives of this CAREER proposal are to: (1) Synthesize layered solvated transition metal oxides, (2) Determine the relationships between charge transfer of monovalent and divalent cations and interlayer solvation, and (3) Determine the diffusion mechanisms of monovalent and divalent cations in solvated interlayers. The research approach is to utilize tungsten and molybdenum oxides because they offer multi-valent redox, diversity of crystal structure, hydrated polymorphs, and stability in both aqueous and non-aqueous electrolytes. Solvated polymorphs will be synthesized from hydrated structures via solvent exchange. The dynamics of cation charge transfer and diffusion will be determined via electrochemical, microscopic, and spectroscopic techniques including in situ methods. The long-term educational goal of this proposal is to train undergraduate and graduate students to understand the relationships between materials, energy, and society, particularly the need for renewable energy in developing countries. The educational plan leverages and extends the SciBridge project, developed by the PI, to engage U.S. and African university students in educational outreach in the area of renewable energy.

The purpose of this work is to understand how the fundamental physics and chemistry of hydrogen-transfer catalysis evolves along the materials design continuum bounded by soluble molecules and macroscopic extended solids. We will focus specifically on electrochemical and thermochemical oxygen reduction at molecular polyoxometalate (POM) clusters and extended metal oxide nanomaterials. Our hypothesis is that elementary charge-transfer mechanisms for PCET are substantially conserved between POM clusters and extended metal oxides with congruent coordination environments. Nonetheless, the structural heterogeneity of extended metal oxides very often yields a spectrum of reactivity where a minority of surface sites are responsible for most of the catalytic activity. Hence, mapping the similarities and differences of PCET along this molecules-to-materials design continuum should make it possible to tune the redox reactivity of extended metal oxide catalysts by analogy to the corresponding POMs. We will therefore pursue a series of hypothesis-driven studies aimed at comparing the mechanisms of hydrogen transfer to dioxygen across molecular and extended solid catalysts under mutually similar conditions, specifically targeting the selective synthesis of H2O2.

Energy storage devices that could be charged and discharged in minutes or seconds while providing high energy densities are necessary for next generation portable electronics, electric vehicles, and in smart grid applications. The proposed research will lead to design rules for controllable, scalable, and customizable manufacturing of a new class of electrode architectures for energy storage based on low density, electrically conductive carbon nanotube foam scaffolds that are hybridized with metal oxides. The research will support the education and training of undergraduate and graduate students on battery material synthesis, electrode manufacturing, device fabrication, and materials characterization.

The Sloan Research Fellowship is in recognition of distinguished performance and a unique potential to make substantial contributions to the field.

The "FIRST" Center has made substantial advances towards understanding the fundamental atomic and molecular level processes controlling the functionality of fluid/solid interfaces. These complex, interrelated processes are a central challenge repeated in many of the DOE BES Basic Research Needs reports, and represent a key bottleneck in many future energy technologies, including electrical energy storage and catalysis. The FIRST Center builds on Oak Ridge National Laboratory������������������s (ORNL) strengths in materials and chemical science, neutron scattering, computation, and nanoscience. It strongly complements ongoing research in our BES Chemical Sciences, Geosciences and Biosciences program, which includes catalysis, geochemistry, and separations and analysis, and in our Materials Science and Engineering program, which includes materials synthesis, energy storage, materials chemistry, microscopy, neutron scattering, and materials theory.