Hu Research Group

Interfaces are integral parts of composite materials and can significantly affect their physical and chemical properties. In biological systems, for example, molecules at the interfaces regulate mineral formation or mitigate structural mismatch of the organic and inorganic moieties to provide optimal mechanical properties. In energy storage systems, interfacial processes play a key role in charge and mass transport, degradation, and safety. A thorough fundamental understanding of these underlying interfacial processes has important scientific and engineering implications. However, due to the intrinsic nature of interfaces being buried and disordered, it is very challenging to reveal chemical, structural, and dynamical information at interfaces. Research in this group leverages the unique in-situ multinuclear high-resolution solid-state nuclear magnetic resonance (NMR) for investigating buried interfaces under operation. By complementing NMR data with those obtained from electron microscopy and x-ray/neutron techniques, a complete picture of structure-property relationship for the interfaces of multilayer functional structures can be established. Specific research interests include:

1. Energy Materials. Efficient use of intermittently generated renewable energy sources, such as wind and solar, requires the development of advanced energy storage technologies. Rechargeable batteries are one of the leading energy storage technologies, widely employed in portable electronics and electric vehicles. However, severe degradation and safety issues have hindered further improvement towards high energy density, low cost, and long shelf life. One major cause of degradation and unsafety is the formation of non-stable solid- electrolyte-interphases (SEIs) from irreversible electrolyte decomposition at the battery electrode surface. Systematic studies on the SEIs in this group can reveal the details of degradation mechanisms, with which mitigation strategies such as electrolyte additives and surface engineering can be implemented and evaluated. Similar research can also be extended to other energy conversion storage systems including fuel cells, capacitors, solar cells, and sensors, etc.

2. Development and Applications of New NMR Characterization Techniques. Many systems that operate in non-equilibrium conditions, e.g., rechargeable lithium-ion batteries, require in situ characterization to follow the reaction processes in real time. Advanced in situ solid-state NMR techniques, including probe hardware and pulse sequences, are being developed in collaboration with scientists at NHMFL. Advanced sensitivity enhancement techniques, e.g. Dynamic Nuclear Polarization (DNP), are particularly being explored as a new technique to characterize functional materials containing low natural abundance and low- quadrupolar nuclei, or samples with limited quantities.

3. Protein-Protein Interactions. Relatively little is known about the cell division machinery, or divisome, of Mycobacteria tuberculosis (Mtb), the causative agent of tuberculosis (TB). Our research interests are to advance knowledge of the Mtb divisome as potential drug targets and towards this end achieve an understanding of how the divisome proteins interact with each other and hence, how they are recruited to the divisome. Four specific transmembrane proteins (CrgA, CwsA, Chiz, and FtsQ) are targeted for structural characterizations, both individually and as complexes. Combined structural characterization tools are implemented, including solid-state NMR, solution-state NMR, DNP and molecular dynamic simulations. We are particularly interested in characterizing the structures of these proteins and protein complexes in in a native-like, lipid bilayer environment, which is a better membrane memetic that does not distort the nascent protein structures. Solid-state NMR is unique in structural characterization of such complex system. We utilize oriented ssNMR to determine the transmembrane topology with respect to the lipid bilayer normal by conventional PISEMA pulse sequence. MAS NMR and DNP methods are used to obtain distance restraints on intra- and inter- protein moieties. Combining restrained molecular dynamic simulations, we can characterize the membrane protein tertiary structures and protein complex interfaces in a native-like membrane environment. These research projects will lead to critical knowledge on the activities and interactions of central layers in the divisome of Mtb.
If you have any questions on bio projects, please contact Dr. Rongfu Zhang (rzhang3@fsu.edu) [Link]