Speaker: Meilin Liu, Professor and Associate Chair, Materials Science and Engineering Georgia Institute of Technology
Title: Surface Modification and In Situ/Operando Characterization of Electrodes for Energy Storage and Conversion
Abstract: The performances of electrochemical systems are often limited by the charge and mass transfer along surfaces and across interfaces - the most active sites for chemical and electrochemical reactions. Fundamental understanding of the rate-limiting steps is vital to achieving rational design of novel electrode materials or structures with enhanced energy and power density. This presentation will highlight some recent advances in surface modifications and characterization of electrodes in energy storage and conversion systems. Surface enhanced Raman spectroscopy (SERS) has been used for probing and mapping new phases and reaction intermediates on electrode surfaces under or near operating conditions. In particular, it is demonstrated that SiO2 shell isolated Ag nanoparticles have excellent chemical and thermal robustness and stability for in situ SERS study of electrode materials under in situ or operando conditions, providing valuable information on reaction intermediates or structural changes that critically influence the performance and stability of the electrodes. Further, synchrotron-based X-ray absorption spectroscopy (XAS) and XPS has been used to characterize the local atomistic structure variation and oxidation state changes of electrode surfaces and interfaces, which may critically affect the activation or degradation processes of electrodes. These experimental studies, together with modeling and simulation, have helped us to gain important insights into the mechanisms of chemical and energy transformation, electro-catalytic reactions, and degradation processes, providing valuable guidelines for rational design of new electrode materials, surfaces, and interfaces with desired functionalities.