(6kp) Functionalized Materials for Sustainable Energy Applications: Structure and Reactivity

Past and Current Research:

Recent advances in material synthesis enable the controllable design and construction of nanostructured model materials for applications in important fields such as catalysis, energy storage and conversion, optoelectronics, gas separation, biomedical diagnosis, etc. The fundamental basis for the optimization of synthetic methodology and development of material structure/performance relationships are still a matter of great interest.

During my Ph.D. research, I studied two-dimensional (2D) nanosheets obtained by delamination of bulk layered materials, which exhibit novel physical and chemical properties, different from their bulk precursors, that are responsible for their excellent performance in energy storage. However, producing atomic thickness 2D nanosheets for large-scale commercial applications remain unrealistic in large scale due to the fragmentation, morphological damage, and re-aggregation of the detached nanosheets associated with the exfoliation process. I developed a novel exfoliation method to achieved single layer 2D nanosheets with large lateral size for energy storage and conversion devices with enhanced electrochemical performance. Through a combination of experimental and theoretical studies, I demonstrated that intercalation of solvated ions weakens the interaction between host layer and interlayer species and promote the total delamination of bulk precursor into single layer 2D nanosheets.

In addition, I studied nanoporous materials and well-defined nanoparticles for emission control, particularly for CO oxidation reaction under moisture. In practical applications, a large proportion of water plays a completely different role in catalytic reactions in presence/absence of precious metals. Water could be either a devastating catalyst poison on transition metal oxides or a promoter on supported precious metal catalysts. However, the high cost of precious metals limits its large-scale commercial applications. Therefore, I developed functionalized materials with a significant reduction in the amount the precious metals by modifying the physical and chemical properties of the materials. The resulting functionalized materials show enhanced water-tolerance and catalytic activity. Through in situ spectroscopic monitoring of reaction, I found that water directly participates in the reaction by formation of active intermediates at metal-support interfaces and lowers the activation barrier of the reaction. I have also utilized these synthetic strategies during my postdoctoral research. Currently, I am working as a postdoc at the University of Oklahoma with Prof. Daniel E. Resasco. We have advanced synthetic methodology–structure–reactivity relationship through comprehensive studies on reaction kinetics and theoretical calculations. We have demonstrated that water can play an unexpected promotional role in some biomass upgrading reactions. In liquid phase reactions, the presence of water changes the kinetics of C-C bond forming reactions by exerting remote-C=O bond polarization from the surface site to the reactant via water bridges. I have demonstrated that this phenomenon only occurs with solvent molecules that are able to create H-bonds, but not with aprotic (polar) solvents.

Future Research:

My future research plans focus on understanding and controlling the interaction between molecules and solid materials within various scales to engineer novel functionalized materials for sustainable energy applications, such as fuel cells and C1 conversion. For example, C1 building blocks, originating from fossil (e.g. natural gas, shale gas) or renewable (e.g. biomass, organic waste) sources, can utilize catalytic process to generate valuable products, which may help alleviating environmental problems and increasing the widespread use of clean energy. Conventionally, C1 molecules are firstly converted to active species for cascade catalytic reactions to form value-added components. These two steps are separated. Developing a multifunctional catalyst for coupling reaction in one-pot is an energy-efficient catalytic route to directly convert C1 molecules into high value compounds. I plan to design multicomponent architectures of functionalized materials with controllable catalytic activity and selectivity on basis of the well-studied surface composition and electronic/geometric structure of catalyst, reaction kinetics and theoretical calculations. I plan to develop a general principle in rational design of structured functional materials for sustainable fuel and chemical production through a variety of chemical transformations.

Teaching Interests:

I have extensive teaching experience with undergraduate and graduate students throughout my academic career, including teaching them material synthesis, characterization and catalytic performance measurements both in the classroom and laboratory. I am interested in teaching any core course in undergraduate chemical engineering, such as Introduction to Chemical Engineering, Mass and Energy Balances, Thermodynamics, Reaction Kinetics, Chemical Reaction Engineering, and Unit Operation Laboratory. Also, I would be interested in developing elective graduate courses such as nanomaterials design for electrocatalysis applications.