(4du) Computational Materials Chemistry for Energy Conversion and Storage Applications

Research Interests
Electrochemical engineering is poised to play a pivotal role in the development of technological alternatives to fossil resources. Electrochemistry is used in energy applications (e.g., fuel cells, electrolyzers, and batteries) and in the synthesis of fuels and commodity chemicals (e.g., water splitting and CO₂ reduction). Because the electrode–electrolyte interfaces in these systems are chemically complex, a detailed molecular understanding of reactions in electrochemical devices can be elusive when probed through experimental measurements alone. Theoretical and computational research, in combination with complementary experimental measurements, can engender a deeper understanding of electrochemical processes.

My research group will apply multi-scale models to describe interfacial electrochemical phenomena to aid in bottom-up materials design for next-generation applications in energy conversion and storage. The foundation of these models will be fundamental theories of electronic structure, thermodynamics, kinetics, and transport. Computational chemistry tools (e.g., density functional theory, molecular dynamics) will be used to gain atomic-scale insights into interfacial structure and reaction mechanisms, in addition to the derivation of input properties for modeling studies.

During my graduate and postdoctoral studies, I developed skills at the intersection of computational chemistry, materials science, and chemical physics to address key knowledge gaps in electrochemical science and engineering. In particular, theoretical and methodological developments from my postdoctoral research will provide my group a distinct perspective toward analysis of electron transfer processes in electrochemical systems. I have experience mentoring graduate students during my Ph.D. and postdoc, which has resulted in five publications. Several research experiences have been in highly collaborative environments between theory and experiment. These have been fruitful experiences given the highly interdisciplinary nature of research problems in energy conversion and storage.

Ph.D. Research
Davidson School of Chemical Engineering, Purdue University, Advisor: Jeffrey Greeley

During my Ph.D., I used computational chemistry techniques to understand and control surface chemistry of lithium ion battery cathodes. Highlights included a theoretical description of electrode surface structures under operating conditions. This laid a foundation for the development of models for the atomic layer growth of protective surface coatings. I applied similar approaches to electrode–electrolyte interfaces in solid-state batteries, which led to new design principles for engineering stable solid–solid boundaries. I also worked on a fellowship project (DOE SCGSR) with Dr. Larry Curtiss at Argonne National Laboratory to model charge transfer in lithium air batteries. These studies were performed in collaboration with experimentalists to further develop the computational models and to provide inputs using materials characterization.

• DOE Office of Science Graduate Research Fellowship (SCGSR), 2017

Selected Publications:

1. Warburton, R. E.; Castro, F. C.; Deshpande, S.; Madsen, K. E.; Greeley, J. et al. Oriented LiMn₂O₄ Particle Fracture from Delithiation-Driven Surface Stress. ACS Appl. Mater. Interfaces 2020, 12, 49182–49191.
2. Warburton, R. E.; Young, M. J.; Letourneau, S.; Elam, J. W.; Greeley, J. Descriptor-Based Analysis of Atomic Layer Deposition Mechanisms on Spinel LiMn₂O₄ Lithium-Ion Battery Cathodes. Chem. Mater. 2020, 32, 1794–1806.
3. Ahmadiparidari, A.^‡; Warburton, R. E.^‡; Majidi, L.^‡; Curtiss, L. A.; Salehi-Khojin, A. et al. A Long-Cycle-Life Lithium–CO₂ Battery with Carbon Neutrality. Adv. Mater. 2019, 31, 1902518. (^‡ equal contribution)
4. Bassett, K. L.^‡; Warburton, R. E.^‡; Deshpande, S.; Greeley, J.; Gewirth, A. A. et al. Operando Observations and First-Principles Calculations of Reduced Lithium Insertion in Au-Coated LiMn₂O₄. Adv. Mater. Interfaces 2019, 6, 1801923. (^‡ equal contribution)
   
5. Warburton, R. E.; Iddir, H.; Curtiss, L. A.; Greeley, J. Thermodynamic Stability of Low-and High-Index Spinel LiMn₂O₄ Surface Terminations. ACS Appl. Mater. Interfaces 2016, 8, 11108–11121 (2016).

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

My postdoctoral research focuses on modeling proton-coupled electron transfer (PCET) for applications in heterogeneous electrocatalysis. I have used constant-potential methods to understand interfacial electric fields and vibrational frequency shifts of solvent molecules near charged surface. These methods have also been used to evaluate PCET thermodynamics within the grand canonical ensemble. My current work is focused on developing methods to model interfacial PCET kinetics using inputs from quantum chemical calculations. These studies are used to connect atomic-level properties inaccessible to experiment to further understand the origins of experimental observables such as proton-coupled redox potentials, turnover rates, and kinetic isotope effects. These fundamental studies of electrocatalytic interface will aid in bottom-up catalyst design for electrochemical applications in fuel cells and electrolyzers.

• Arnold O. Beckman Postdoctoral Fellowship in Chemical Sciences, 2021
• University of Washington Distinguished Young Scholars Seminar (DYSS), 2020

Publications:

1. Hutchison, P.; Warburton, R. E.; Soudackov, A. V.; Hammes-Schiffer, S. Multicapacitor Approach to Interfacial Proton-Coupled Electron Transfer Thermodynamics at Constant Potential. submitted.
2. Sarkar, S.; Maitra, A.; Lake, W. R.; Warburton, R. E.; Hammes-Schiffer, S.; Dawlaty, J. M. Mechanistic Insights about Electrochemical Proton-Coupled Electron Transfer Derived from a Vibrational Probe. J. Am. Chem. Soc. 2021, 143, 8381–8390.
3. Warburton, R. E.; Hutchison, P.; Jackson, M. N.; Pegis, M. L.; Surendranath, Y.; Hammes-Schiffer, S. Interfacial Field-Driven Proton-Coupled Electron Transfer at Graphite-Conjugated Organic Acids. J. Am. Chem. Soc. 2020, 142, 20855–20864.

Teaching Interests

Both within the classroom and in research, teaching has been a fulfilling aspect of my career thus far and has been a key motivator driving me toward an academic position. I aim to effectively communicate the technical concepts that will help students in their future careers, while fostering an inclusive, respectful, and welcoming learning environment for all. I have classroom teaching experience as an undergraduate and graduate teaching assistant across precalculus, chemical engineering thermodynamics, and unit operations courses. During graduate school, I was a substitute lecturer during several undergraduate thermodynamics classes. I also aided in the instruction for my advisor’s graduate computational catalysis elective, wherein I gave guest lectures on special topics in catalysis and helped guide hands-on computational chemistry tutorials.

I am willing and able to teach any chemical engineering core course, with a special interest in either materials and energy balances, thermodynamics, kinetics and reaction engineering, or engineering math. Depending on departmental needs, I am also interested in developing elective courses on either electrochemical engineering or computational materials chemistry. I am in the process of obtaining the Certificate of College Teaching Preparation through the Yale Poorvu Center for Teaching and Learning. My goal through this program is to augment my teaching skills through exposure to evidence-based pedagogical approaches.