(3dn) Synthesis-Structure Relationships in Plasma Modified Catalysts and Catalyst Synthesis

The growing interest in synthesizing or activating catalytic materials using dry chemical processing techniques hinges on the ability to understand the relationships between plasma chemistry and the catalytic activity of the final material. The underlying physics involved in performing material transformations in plasmas, that otherwise require elevated temperature, often points us towards manipulation of plasma parameters, such as ion energy as a means to locally deliver energy without broad heating. In this session, two distinct opportunities will be presented where advances in tunable plasma sources, at both vacuum and atmospheric operating conditions, enable either new materials development or new synthesis routes for catalytic and electrochemical materials.

Transition Metal Carbide Alloys for Fuel Cell Electrode Corrosion Resistance

Transition metal carbides (TMCs) play a critical role in the functionality of engineered systems related to energy storage, and applications requiring corrosion resistance, high temperature and strength. The physics regulating TMC material properties is controlled by both atomic and mesoscale structures. Unconventional carbide phases recently published have shown the ability to access enhanced electronic conductivity, catalytic activity, and mechanical properties. Herein lies the opportunity for high-power impulse magnetron sputtering (HiPIMS) to provide a transformative approach to non-metal systems such as metal carbides. A TMC alloy, possibly metastable, will have the ion energy of deposited atoms controlled precisely by the magnitude of the HiPIMS “kick pulse” depicted in Figure 1. In carbide systems especially, this kick will be needed since the energy required to alloy metals may be low while the implant energy for the carbon to form an interstitial carbide in the lattice may be significantly higher, and variable with the alloy of choice.

This thrust will have several themes: 1) Demonstration of new metastable TMCs. 2) Development of electrocatalysts for high temperature fuel cells based on corrosion resistance and alloy stability. 3) Determination of structure-property relationships for TMC alloys including effects of strain on electrochemical resistance, oxygen binding energy, etc. Future foci of this thrust include other catalytic materials and functional coatings beyond TMCs with the intention to develop advanced photo/electrocatalysts through the use of strain engineering and gradient composition films.

Microwave Non-Thermal Atmospheric Plasmas for Single-Step Catalyst Synthesis

Synthesis of conventional mixed metal-metal oxide heterogeneous catalysis through plasma deposition and low temperature calcination demonstrated the viability of alternate synthesis routes for these materials at a scale required by commercial applications for the final materials. Dielectric Barrier Discharges (DBD) gained early favor for their ability to be scaled easily, but lacked the density of plasma or energy distribution required for all processes. In a number of systems, particularly nickel oxide systems, precursor decomposition was incomplete and required additional processing steps to produce a finish catalyst. In other systems, particularly precious metal decorated systems, DBDs may not produce the required ion energies to completely remove impurities or effect structural changes to the material that lead to significant increases in activity. Microwave driven surface wave plasma torches offer the opportunity to study the effect of plasmas on material properties and catalytic activity at atmospheric pressure.

This thrust will have themes: 1) Demonstrate the increased plasma densities and ion energies of microwave driven plasmas at atmospheric pressure can overcome existing synthesis challenges in conventional catalyst systems. 2) Develop sputtered nanoparticle synthesis techniques for metallic catalysts at atmospheric pressure. 3) Implement single step synthesis routes at atmospheric pressure including preparing support substrates, formation of metal and metal oxide particles by chemical vapor deposition or sputtering, and adhering of these particles to the support on a roll to roll type system for high volume manufacturing.

Research Interests:

As an assistant professor, my efforts will be grounded in experimental research with a focus on design of materials through better understanding of synthesis-structure-property relationships. Specifically, I seek to advance the practices used in the areas of catalyst synthesis by dry chemical processing as well as plasma modification of catalytic materials. The program will take advantage of the recent advances in plasma sources both in vacuum processing as well as at atmospheric conditions. The outputs from my laboratory will address a variety of technological and materials needs through the engineering of advanced functional coatings, electrochemical and catalytic materials.

The first thrust of the program is enabled by advances in high-power impulse magnetron sputtering (HiPIMS) kick pulses. It seeks to develop new transition metal carbide alloys for electrochemical corrosion resistance in fuel cells through the manipulation of ion energy distributions during reactive sputtering. The second thrust is enabled by the development of microwave driven, cold (non-equilibrium) plasma torches with significantly greater plasma density that previous DBD devices offered. Here, the development of single step catalytic particle synthesis processes will be sought based on previous success in developing multilayer deposition processes at atmospheric pressure for conversion coatings.

Funding for these activities will be sought from a variety of federal sources depending on both the theme and application. Materials discovery solicitations, particularly from the United States National Science Foundation – Division of Materials Research (NSF-DMR), will be instrumental in the success of the HiPIMS thrust. This project has excellent potential for collaborations with first principal computational groups, as well as data science/predictive material researchers. Department of Energy catalytic material development solicitations, as well as NSF Plasma Physics division will focus targets for the atmospheric plasma processing thrust.

Teaching Interests:

The ability to consider the needs of the student first and foremost when teaching begins with a mutual understanding between the students and the instructor. The typical student in STEM programs is, in addition to intelligent, a self-motivated individual with a sincere desire to connect to the material. Students maintain high expectations for the quality of instruction they receive, and they demonstrate their commitment by not shying away from conceptually dense, fast paced, and challenging coursework. The core of my teaching philosophy concerns how may I best be able to guide students to their ‘Eureka moment”, enabling students to feel a sense of ownership of their discovery of a concept offering them a boost in self-confidence alongside their learning.

I focus on offering multiple ways of approaching concepts, analogies, and unique real world examples to allow students to make the connections, without brute force repetition. I have found that the incorporation of real world problems is crucial to students gaining an understanding of chemical processes everywhere from the atomic scale to the production plant scale. Stories and analogies provide an ideal avenue for instructors to force themselves to explain a technical detail from an alternate perspective that will aid students who learn differently from their peers. Perspective about the historical development of a field or process will foster an appreciation and understanding for how the field achieved its present notoriety, as well as help promote the creative thinking that is required of the future innovators that the field will produce. This perspective also encourages former students and instructors to continue to correspond beyond their time on campus together.

My philosophy is a product of a many life experiences beginning with family members who are educators spanning pre-school to university faculty. Evolution of my philosophy began in earnest as a freshman running review sessions with a classmate and coalesced throughout teaching experiences in graduate school. I was a Teaching Assistant for three semesters aiding Thermodynamics, Kinetics/Reactor Design, and Senior Design. My experience covered nearly all aspects of course implementation including lecturing, development and grading of assignments, review material, and exams, coordination with disability resources and other course administration, and revision of syllabus policies for electronic equipped classrooms. Following this, I continued to teach lectures my PI and found opportunities to experiment with my teaching style incorporating various forms of active learning and early informal feedback.

I would enjoy teaching thermodynamics and reaction kinetics given my past experiences. I would seek to expand on elective course offerings related to electrochemistry, catalysis, plasma chemistry, plasma processing, and semiconductor manufacturing at both the undergraduate and graduate levels. My proposed research program offers significant room for a variety of demonstrations built into coursework as well as the potential for development of future laboratory sections of those courses.

I will be a strong proponent of public speaking, effective technical writing, and other communication skills for the students in my classes. As many students, both undergraduate and graduate, will not have the time or opportunity to take a technical writing class, more of those lessons must be injected by experienced instructors who wish to see their students succeed.