(3x) Nanoengineering Materials for Sustainable Processes: Synthesis, Reaction Kinetics and First-Principles Modeling

Past and Current Research:

Recent advances in synthesis enable the controlled design and construction of nanostructured 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. During my thesis work, I developed a novel exfoliation method to achieve single-layer 2D nanosheets with large lateral size, which is favorable 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, a method that could be amenable to scale-up.

In addition, I studied nanoporous materials and well-defined nanoparticles for gas-emission control, particularly for CO oxidation in the presence of moisture. In practical applications, the presence of water can play different roles in catalytic reactions, depending on the presence/absence of precious metals. Water could be either a devastating catalyst poison on transition metal oxides or a promoter on supported precious metals. However, the high cost of precious metals limits its large-scale commercial applications. With this in mind, I developed functionalized materials with a significant reduction in the amount the precious metals by modifying their physical and chemical properties. 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 forming active intermediates at the metal-support interface and lowering the activation barrier for the reaction.

I have also utilized these synthetic strategies, combined with rigorous kinetics analysis, during my postdoctoral research. Currently, I am a research associate at the University of Oklahoma in the group of Prof. Daniel E. Resasco. We have developed synthesis–structure–reactivity relationships by combining comprehensive studies on rational design and characterization of well-defined nanomaterials, detailed reaction kinetics and theoretical calculations of surface reactions. Among a number of high-impact studies, we have demonstrated that water can play an unexpected promotional role in some organic reactions, relevant to biomass upgrading. For example, we have found that the kinetics of C–C bond forming reactions changes in the presence of water, which exerts remote-C=O bond polarization from a surface site to the reactant via water bridges. Combining kinetics and my own DFT calculations, I have demonstrated that this phenomenon only occurs with a solvent like water that is able to create H-bonds, but not with aprotic (polar) solvents.

Future Research:

Developing catalytic materials and processes is crucial to generate sustainable energy, which may help alleviating environmental issues associated with the use of fossil fuels. My future research plans focus on understanding and controlling the interaction between molecules and multifunctional materials by using hybrid technologies for sustainable energy applications, such as fuel cells and C1 conversion. I plan to design multicomponent architectures of functionalized materials with controlled catalytic activity and selectivity based on well-characterized surface composition and electronic/geometric structure, rigorous reaction kinetics analysis and theoretical calculations. These studies will 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 , including teaching material synthesis, characterization and catalytic measurements, both in the classroom and the laboratory. I will be delighted teaching any core course in undergraduate Chemical Engineering, such as Thermodynamics, Reaction Kinetics and Chemical Reaction Engineering, and Unit Operations Laboratory. Also, I would be interested in developing elective graduate courses such as Nanomaterials design for catalysis and electrocatalysis applications.

Selected publications:

(1) G. Li, B. Wang, D. E. Resasco, “Water promotion (or inhibition) of condensation reactions depends on exposed cerium oxide catalyst facets” ACS Catal. 2020, 9(10), 5373-5382.

(2) G. Li, B. Wang, D. E. Resasco, “Water-mediated heterogeneous catalysis” ACS Catal. 2020, 10, 2, 1294-1309.

(3) G. Li, S. Dissanayake, S. L. Suib, D. E. Resasco, “Mesoporous oxide catalysts for aldol condensation of cyclopentanone. Copmarison of activity and stability of Meso-CeO₂ and Meso-ZrO₂” Appl. Catal. B: Environ. 2020, 267, 118373.

(4) G. Li, B. Wang, B. Chen, D. E. Resasco, “Role of water in cyclopentanone self-condensation reaction catalyzed by MCM-41 Functionalized with sulfonic acid groups” J. Catal. 2019, 377, 245-254.

(5) G. Li, L. Tan, Y. Zhang, B. Wu, L. Li, “Highly efficiently delaminated single-layered MXene nanosheets with large lateral size” Langmuir 2017, 33, 9000-9006.

(6) G. Li, L. Li, Y. Yuan, J. Shi, Y. Yuan, Y. Li, W. Zhao, J. Shi, “Highly efficient mesoporous Pd/CeO₂ catalyst for low temperature CO oxidation especially under moisture condition” Appl. Catal. B: Environ. 2014, 158-159, 341-347.