With support from the Chemical Measurement and Imaging Program and the Catalysis Program in the Division of Chemistry, Professor Ning Fang of Georgia State University and Professor Wenyu Huang of Iowa State University are developing a three dimensional super-resolution imaging technique for understanding molecular movement and reactivity in nanopores at the single-molecule level. Highly tunable core-shell structures with well-defined geometry and manageable complexity are designed and synthesized, and then visualized under the optical imaging systems. The in situ 3D imaging capability of the proposed microscopes makes them valuable characterization techniques complementary to other conventional methods, such as electron microscopy and atomic force microscopy. Both teams are also designing single molecule imaging experiments to study multi-step catalytic reactions, in which two or more chemical transformations are catalyzed with a nanoscale-engineered multifunctional catalyst to avoid the need for separation, purification, and transfer of intermediates produced in each step. Graduate and undergraduate students in these two institutions acquire valuable skills in building catalytic nanostructures and in developing new instrumental capabilities to understand molecular transport and catalysis at the single-molecule level. High school students in the Atlanta and Ames area are exposed to the concepts of imaging, nanoscience, and catalysis to enhance STEM education in high schools.
In this work well-defined heterogeneous catalytic systems, whereby colloidal nanoparticles are embedded within core-shell mesoporous silica materials of aligned channels, are developed. Single molecule trajectories with nanometer resolution are acquired to elucidate the effects of pore size, length, orientation, and surface ligands on molecular transport and conversion. New experimental insights on transport in nanoscale confinement acquired with the model core-shell porous structures can be generalized to guide the development of porous materials for separation and catalysis. The long-term objective for this research is to use the knowledge acquired using the imaging technique on the platform catalysis system to guide our future catalyst design for a wide range of chemical transformations.