Speaker: Gang Wan, SLAC
Program Description:
Tuning the redox reactions at (electro) chemical interfaces provides efficient and sustainable pathway for energy and chemicals harvesting. However, both cationic and anionic redox behaviors are often accompanied by the ionic diffusion, triggering the transformation of the surface structure and the evolution of various interphases. This lies at the heart of chemical phenomena that take place at various interfaces. Therefore, atomic insight into the structural and chemical transformations of both interphase and interface is considered critical in further advancement of functional materials and technological innovations that could be implemented in various electrochemical systems.
In this talk, the research effort aimed to the fundamental understanding of diffusion and transition processes that are relevant to the interfacial reactivity and stability of functional oxides will be presented. With epitaxial oxide thin-film grown on substrates as model system, we examined the structural evolution of oxides during various transformation processes using a combination of electrochemical measurements, synchrotron X-ray surface scattering, and X-ray spectroscopic studies, with an objective to identify how the ion diffusion and reconstruction of the surface that activate the oxide surface and the underlying process of phase transformation. Our studies highlight the critical role of the diffusive coupling and lattice oxygen activation when forming the active disordered materials and the opportunities brought by interfacial transitions toward emerging applications.
