(3ct) Multiscale Multipronged Materials Design for Catalysis and Renewable Energy: From Methane Conversion to Water Purification, Batteries and Efficient Photovoltaics

(PI: Prof. Andrew M Rappe)

Previously: 2-Year Postdoc at Chemical Engineering Dept., Stanford University

(PI: Prof. Jens K Nørskov)

Ph.D. in Physics, Yale University

Dissertation:

“Using Ferroelectrics to Tackle Fundamental Challenges in Catalysis”

(Advisor: Prof. Sohrab Ismail-Beigi)

Research Interests:

My main expertise is theoretical materials design. In the last few decades, rising computing power and development of density functional theory (DFT) methods, have made atomistic study of surfaces and reaction mechanisms a central aspect of catalysis. We have also realized some of the fundamental limitations of this field dictated by the “scaling-relations” and the Sabatier principle. Now, the quest is to devise materials that break these limitations.

The computational framework as well as the basic physics and chemistry involved in designing and understanding catalytic surfaces, can be integrated with similar tools that can devise materials for sustainable water purification, efficient photovoltaics or long-life high-capacity batteries. By interconnecting ideas from these seemingly different fields, I can establish a multiprong approach in which using the light-matter interaction and quantum photovoltaic phenomena, energy of (solar) photons are extracted and put into work in the form of energetic electrons and holes. Such high energy charge carriers once directed to appropriate active sites with tailored chemistry (via appropriate interfacial band alignment engineering), can run chemical reactions and catalytic cycles. Catalysis can be either at work to produce specific chemicals, to facilitate storing the electric energy (with minimal charge/discharge overpotentials) in batteries, or to produce (in situ) reactive oxygen species to purify water. What connects renewable energy, batteries and catalysis to water purification? The rapidly growing human population needs access to more energy and clean water. The devastating force of climate change necessitates a paradigm shift from our conventional energy resources to renewable ones. In parallel, shrinking drinkable water sources increases the energy demand (for purification, transport and storage), putting more stress on our limited renewable power. Better catalysts, batteries, and photovoltaics offer cheaper energy and greater (distributed) power, while new materials can render water purification less energy-intensive.

It should be noted that due to the overwhelming amount of human-made CO₂ already released to the atmosphere, we need to go further than decreasing CO₂ emissions by actively capturing and reducing the excess amount of CO₂ to useful chemicals. Such a reaction although simple on paper, is associated with complex open questions, including how to suppress the parasitic hydrogen evolution reaction (HER) and enhance selective conversion to carbon-rich products. I believe that a comprehensive approach to address such real-world challenges cannot be limited to ab-initio DFT calculations, but comprises a multi-scale approach employing classical molecular dynamics or hybrid methods mixing quantum chemical and DFT-level information with atomistic potentials optimized employing neural networks or machine learning. Continuous or Kinetic (Monte Carlo) models will then bridge the remaining gap in order to connect what goes on in supercomputer's CPUs or GPUs to an active electrode material in the heart of a futuristic industrial-scale electrocatalyst.

Future plans for my research group, in addition to above, will include connecting different research fields. A central theme of my research in the last few years has been single-atom catalysis (SAC). I am going to blend this approach with my ferroelectric works, making it possible to exploit the bulk photovoltaic, pyro-, or piezoelectric effect in ferroelectrics to control the flow of electrons into transition metal single-sites and actively engineer their chemistry. At Stanford I have delineated the role single sites can play in selective methane conversion, I plan to combine this line of research with ferroelectrics and hybrid perovskites. Pathways to achieve the single (transition-metal) site architecture include using MOFs or metal doped COF-based materials. I am also going to explore the porous nature of COFs for water purification. My ferroelectric research can also relate to the water purification front as the pyroelectric effect is shown by my previous theory work and recent experimental works to be able to produce reactive oxygen species. Ferroelectrics can also be a great framework to support the metal single-sites, and I intend to explore the unique opportunities arising from merging these two worlds with a focus on CO₂ reduction problem and selective methane conversion. Ferroelectrics can break limitations by the Sabatier principle, while SAC breaks those of scaling relations: The promise of combining them is evident!

Participation in Grants: Here at Penn, I have been involved in grant writing for multiple agencies including ONR, EFRC, DOE and NSF, as part of both small or large (multi-PI) proposals. These included both catalysis and hybrid perovskites (photovoltaics) grants. I have also been active in writing multiple computational XSEDE (NSF) grants at Yale.

Postdoctoral Projects:

Penn:

• Understanding the water stability of hybrid perovskites
• Mechanical properties of flexible layered hybrid perovskite optoelectronics
• Tuning electronic properties of 2D perovskites by functionalized organic ligands
• Comprehensive entropy-driven defect suppression of perovskite quantum dots (LEDs)
• Novel electrochemical synthesis of COFs
• Metal-doped single sites in COFs for enhanced ORR
• Selective CO₂ reduction reaction (CO₂RR) to C3-C4 products on nickel phosphides
• Comparative study of HER on a wide class of nickel phosphides
• Developing oxide monolayers on molybdenum phosphide (Mo₃P) nanoparticles systems for ORR/OER catalyst in Li-air batteries.
• Selective CO₂RR using ionic liquids and Mo₃P
• Ferroelectric catalysis
• Light-matter interaction, charged defects and polaronic effects in WS₂ monolayers
• High-throughput study of single-site transition metals in a class of 2D materials
• Study on the effect of Lithium doping on T-Nb₂O₅ electronic properties
• Investigating the growth mechanism of complex oxide heterostructures
• Enhanced polymerization of acrylates via solvated small molecules

Stanford:

• Developing scaling relations and mechanistic insight for heterogeneous methane activation
• Designing hybrid-materials strategies for selective partial oxidation of methane to methanol
• Single-atom catalysts design for selective methane to methanol
• Reversible atomization and nanoclustering of Pt on spinel and application to propene oxidation
• Developing universal scaling relations among closed-shell molecules (including water, alcohols, ammonia etc.) using a high-throughput study.

PhD Research Experience:

My research at Yale, was focused on going beyond the fundamental limitations of catalysis, imposed by the Sabatier principle. Such limitations stem from static surface chemistry of conventional catalysts, and the necessity of reaching an optimum surface-adsorbates interaction (compromise between adsorption and desorption), corresponding to the “top of the Volcano”. Ferroelectrics possess a permanent bulk polarization vector (electric counterpart to magnetization). I illustrated how manipulating this vector (using knobs such as temperature, strain or electric field), grants us an active control over the surface chemistry: using a polarization-cycle, we achieve dynamic catalysis, not bound to a special point on the Volcano, but exploiting both strong adsorption and desorption regimes (alternatively) to perform the overall catalytic cycle. Examples of reactions I studied are direct catalytic decomposition of NO_x into N₂ and O₂ in oxygen-rich environment (impossible reaction if using conventional materials due to scaling relations) and thermal water splitting (with low-grade heat).

Teaching Experience:

I see teaching as a source of joy. I was one of the youngest TAs in my college (University of Tehran), beginning at my junior year by teaching Mathematical Physics. In my senior year I became the TA for Quantum Mechanics for both semesters. Throughout these semesters I had 5-6 hours a week in-person interaction with students (beside grading), which I used for teaching problem solving techniques and different course subjects. Being exposed to teaching from when I was 20, made me able to create a good teaching connection to students, and understand how to convey complex topics in an easy-to-understand and engaging manner. I then continued to TA both lab and theory courses for 10 semesters at Yale; where I also supervised an undergrad for a summer project. Additionally, I participated in multiple outreach activities. At Stanford I mentored a M.Sc. student. At Penn, I have mentored 2 undergrad student, and 3 Ph.D. students on a wide variety of topics, from polymerization, to electrocatalysis and light-matter interaction. Mentoring multiple students and teaching for a total of 13 semesters, has prepared me to effectively take on advising and teaching roles in my academic career. I have honed my skills to assist my students search for a deeper understanding. What is the most important takeaway for a future engineer or scientist is how to apply and generalize the limited knowledge learned in the class room, through critical thinking and problem-solving skills, to real-world problems and challenges they will face in their careers. Although my undergraduate degree is in Physics, the aforementioned skills enabled me to teach myself throughout my career important aspects and courses in Chemical Engineering and Chemistry, and I am now fully capable of teaching multiple Chemical Engineering courses. My specific teaching interests include Mathematics, Thermodynamics, Kinetics, Statistics, Fundamentals of Materials, Mass and Energy Balances, Transport Phenomena, Physical Chemistry, Physics, Electric Circuits and Computational Methods. If the department deems appropriate, I can design courses in graduate level on the topic of computational materials modeling or catalyst design. As a person who has suffered from ethnic injustice, I am absolutely committed to help creating a diverse and inclusive working and learning environment for us humans.