(3an) Computational Materials Electrochemistry for Energy Conversion and Storage

Electrochemistry is central to many of the renewable energy technologies intended as a response to over-consumption of fossil resources; the applications range from fuel cell and electrolyzer catalysis to energy storage in rechargeable batteries. Gaining a holistic understanding of electrochemical reactions at the molecular scale, however, remains a complex endeavor. This knowledge gap is an impediment to the rational design of materials for energy storage and electrocatalysis with suitable performance and long-term stability. In my Ph.D. and postdoctoral research, I have developed skills in computational chemistry, materials science, and chemical physics to address some of the key research problems in electrochemical energy conversion and storage. I have extensive experience in interdisciplinary collaborations as part of three multi-institution research centers, since many of these research problems necessitate the close interplay between experiment and computation to move the field forward.

My research group will use computational methods (e.g., density functional theory, ab initio and classical molecular dynamics) to study the microscopic properties of materials used in electrochemistry. Atomistic modeling will be combined with theories of thermodynamics, reaction kinetics and engineering, transport, and electronic structure to develop multi-scale models in order to understand and design materials for applications in electrochemical energy conversion and storage. We will focus on modeling ion-coupled electron transfer kinetics in bulk solids and at interfaces, in addition to elucidating atomic structures and interfacial chemistry at solid-vacuum, solid-liquid, and solid-solid interfaces. Ion-coupled electron transport studies will describe the interdependence of ion and electron transport in battery electrodes. There will be a particular focus on long range charge transfer in bulk materials and at interfaces in which the kinetics deviate from transition state theory, as has been observed in recent experimental measurements. These techniques will also be used to study electrocatalytic reactions (e.g., oxygen reduction, water splitting, CO₂ reduction) and specifically the nature of the constitutive proton-coupled electron transfer (PCET) steps between different classes materials (e.g., metals, oxides, phosphides). This research thrust will overlap with interfacial characterization efforts involving bulk and surface thermodynamic analyses of solid electrode materials, along with explicit and continuum models of liquid solvents at the interface. This work will aim to describe, at the atomic level, the solid-state and interfacial chemistry of electrodes and electrolytes in energy storage and electrocatalysis. These efforts, in combination with future experimental collaborations, will be used to both understand fundamental electrochemistry and use these principles to rationally design new materials for electrochemical energy storage and conversion with enhanced performance and long-term stability.

Ph.D. Research

Davidson School of Chemical Engineering, Purdue University, Advisor: Jeffrey Greeley

My Ph.D. research was focused on developing computational models to understand and control interfacial chemistry in lithium ion batteries. Much of my graduate work focused on the surface chemistry of lithium ion cathodes. These studies helped to elucidate equilibrium surface structure of cathode materials and led to the development of molecular-scale descriptors for atomic layer growth of protective surface coatings to mitigate reactivity with the electrolyte. These computational descriptors enabled a physics-based, data-driven approach to the prediction of surface coating mechanisms that can rationally stabilize electrode-electrolyte interfaces, in which these predictions were experimentally supported by in-situ growth measurements and electrochemical cycling. I applied similar approaches to solid-solid electrode-electrolyte interfaces in solid-state batteries. This analysis led to new design principles for engineering stable interfaces in solid-state batteries, based on a description of interfacial thermodynamics and metal-semiconductor band alignment physics. Under a DOE graduate fellowship, I also spent eight months working at Argonne National Laboratory with Dr. Larry Curtiss studying techniques to model charge transfer in lithium ion and lithium air batteries. This work incorporated electronic coupling calculations between electronic ground- and excited-states, providing a computational framework to study charge transfer between non-covalent donor and acceptor redox sites. Each of these studies during my Ph.D. were performed alongside experimental collaborators of various backgrounds to aid in materials characterization, as well as in the further development and validation of computational models.

Postdoctoral Research

Department of Chemistry, Yale University, Advisor: Sharon Hammes-Schiffer

Over the past six months as a postdoc, I have been interested in modeling interfacial electric fields and proton-coupled electron transfer (PCET) for applications in heterogeneous electrocatalysis. In heterogeneous electrocatalytic reactions, the elementary electrochemical steps are PCET reactions; these PCET reaction mechanisms are therefore crucial to understanding reaction pathways and turnover rates. In contrast to PCET in molecular systems, however, the individual electron- and proton-transfer steps in heterogeneous catalysis are often difficult to understand in isolation. Calculated interfacial electric field profiles over the length scale of molecular adsorbates have been used to elucidate the role of electron transfer in PCET reactions. This analysis has aided in understanding mechanisms of the individual electron- and proton-transfer steps at well-defined molecular active sites, which has broad implications for understanding the role of electron transfer and local electric fields toward PCET reactions in heterogeneous electrocatalysis. These studies are meant to connect atomic-scale quantum effects to further understand experimental observables (e.g., proton-coupled redox potentials, turnover rates, kinetic isotope effects) in order to establish design principles for the design of catalytic materials.

Teaching Interests

My teaching experience began as an undergraduate teaching assistant in the Ohio State Math Department, where I spent four semesters as a teaching assistant for recitation help sessions. The summer after graduation I worked as a teaching assistant for Chemical Engineering Unit Operations Laboratory running the Hydrogen Fuel Cell experiment, where I was responsible for supervising students in hands-on laboratory training, grading lab reports, and developing problems for the final exam. In graduate school, I was a teaching assistant for Chemical Engineering Thermodynamics for two semesters where my responsibilities included teaching recitation sessions, holding office hours, and grading exams. I also had the opportunity to serve as a substitute lecturer for a couple classes. I also helped with instruction for my advisor’s “Advanced Modeling for Catalysis Studies” graduate elective, where I gave several guest lectures on special topics, in addition to guiding hands-on computational chemistry tutorial sessions. During my postdoc, I have helped my advisor develop teaching materials to integrate some basic principles of computational condensed matter physics into her quantum chemistry elective course.

I would be most interested in teaching thermodynamics, kinetics/reaction engineering, or mass and energy balances. However, I would be able to teach any chemical engineering core course based on departmental needs. I am also interested in developing elective courses focused on: 1) fundamentals of electrochemistry and electrochemical engineering, and 2) computational materials chemistry.