(6be) Developing Active, Selective, and Energy-Efficient Heterogeneous Catalytic Processes for Enhanced Sustainability

Our society is facing serious energy and environmental issues due to the extensive use of fossil fuels. Catalysts are at the heart of most current processes to convert both renewable and non-renewable resources; and thus, the design of improved catalytic materials is critical in the more efficient utilization of these resources into fuels and chemicals. Unraveling the active sites of catalysts, where the reaction actually occurs, could lead to breakthroughs in chemical industry since approximately 85-90% of the products of chemical industry are made through catalytic processes. Fundamental understanding of catalytic active sites will enable the design and synthesis of superior catalysts with more active and selective sites for efficient utilization of hydrocarbon resources. Despite many efforts to understand the nature of active sites, atomic level understanding of catalytic mechanisms for chemical transformations is limited and the active sites responsible for these transformations are largely unknown.

During my Ph.D. at the University of Wisconsin-Madison under the supervision of Profs. James Dumesic and George Huber, I focused on identifying and studying interfacial catalytic active sites using in situ characterizations to accurately describe reaction kinetics and elucidate mechanisms occurring on catalyst surfaces. I also developed new synthetic routes to prepare catalysts with controlled particle size and composition, with an important application being the selective conversion of biomass-derived molecules to value-added chemicals or fuels. The synthesis of catalysts by traditional methods may produce a wide distribution of metal particle sizes and compositions; and thus, results from spectroscopic and reactions kinetics measurements have contributions from a distribution of active sites. This heterogeneity makes it difficult to assess how the size and composition of the metal particles affect the nature of the surface, the active sites, and the catalytic behavior. Therefore, I developed new methods to synthesize bimetallic nanoparticles with controlled particle size and composition to achieve an effective link between characterization and reactivity, and between theory and experiment.

I successfully identified active sites and reaction mechanisms using the well-defined bimetallic catalysts in many reactions during my Ph.D. research, but the heterogeneity of interfacial sites depending on the location of primary metal sites (i.e. surface, step, and corner) where secondary metal was deposited impedes the accurate assessment of the nature of active sites at the atomic level. During my postdoctoral research at the University of California-Santa Barbara with Prof. Phillip Christopher, I am working on the synthesis and characterization of atomically dispersed catalysts bearing active sites that exhibit catalytic specificity rivaling homogeneous catalysts. Atomically dispersed metal catalysts have uniform active site structures and allow control of the local environment surrounding the active site. Therefore, I demonstrated new synthetic protocol to regulate the local coordination environment of atomically dispersed Rh on Al₂O₃ through a systematic tuning of interactions between Rh and ReO_x and between Rh and WO_x acidic sites. I also established correlations between local coordination environments and catalytic properties of atomically dispersed catalysts.

As a principal investigator, my overarching research goals are in the area of identifying and quantifying active catalytic species using in situ and operando kinetic and spectroscopic characterizations for thermally, light-enhanced, and electrochemically catalytic reactions. I am particularly interested in studying three research areas. First, on the basis of my thesis and postdoc work studying the effect of interfacial sites and local environments on catalytic reactivity, I propose to extend these studies to systematically investigate active phases of interfacial sites using the catalysts with different interfacial geometry. Second, I plan to study the effect of light illumination on the change in reaction kinetics and mechanism using in situ and operando kinetic and spectroscopic characterizations. Last, I would like to investigate the reaction mechanism and key surface intermediates at atomic level for electro-catalytic reactions using in situ and operando spectro-electrochemical techniques such as ATR-IR. All three research interests are unified by the challenge of understanding the fundamental concepts governing the reactions under reaction conditions.

Teaching Interests:

I have diverse teaching experiences including teaching assistantships/research mentioning program for undergraduate students during my graduate school studies and teaching assistantship at an alternative school for socially and academically challenged middle school students. When I worked as a teaching assistant during my graduate school studies at the University of Wisconsin-Madison, I delivered a lecture when a professor was absent, helped to set questions in examinations, and held weekly discussion and review sessions for Process Synthesis class. I also mentored three undergraduate students participating in undergraduate research program during my graduate school and postdoctoral scholar. I formulated research problems and help them to build basic research skills and develop research questions. When I served as a teaching assistant in an alternative school, I instructed and mentored socially and academically challenged middle school students. By engaging in deep conversations and spending quality time with them inside and outside the classroom, I tried to help to shape and set their plans after graduation for their future.

Additionally, I fulfilled numerous teaching and service-oriented responsibilities as an outreach educator during graduate school and postdoctoral scholar. For example, I participated as a volunteer at “Engineering Expo” in the University of Wisconsin-Madison aimed to spark young students’ interest, motivation, and enthusiasm towards science and Engineering. As a part of members of “Materials Research Outreach Program” at the University of California-Santa Barbara, I also served as an instructor in many outreach programs such as “Build a Solar Car” and “It’s a Material World” for students and members of the community.

As a faculty member, I am interested in teaching core classes of Chemical Engineering and designing new classes such as Instrumental Analysis for Chemical Engineers, Advanced Reaction Kinetics and Catalysis, Fundamentals of Process Safety, and Renewable & Sustainable Energy based on my research background and experience. I believe that the most important role as an instructor is sparking intrinsic motivation – deep internal motivation– from students to engage in classes actively and take ownership over their learning. I will try to introduce interesting and practical examples of classroom knowledge applied in the real world to keep students engaged and excited.