Electrocatalysis in Solid Systems: Fundamental Studies for Technological Breakthroughs

Mar 24

Monday, March 24, 2014

1:00 pm - 2:00 pm
Hudson Hall 207


Sossina M. Haile - California Institute of Technology

Electrocatalysis underpins many critical energy conversion technologies, including fuel cells, batteries, photocatalysis, and others, yet, the basic pathways by which it occurs remain largely unknown. Electrochemical impedance spectroscopy in combination with geometrically well-defined electrodes provides a powerful tool for exploring and uncovering mechanistic characteristics of the relevant reactions. The resulting insights enable rational design of advanced electrode structures with exceptional performance. We provide examples from our fuel cell studies of the exploitation of this strategy. We find, from the first study, that hydrogen is readily electro-oxidized directly on the surface of cerium dioxide, even in the absence of metal catalysts. This insight motivates the creation of nanostructured ceria electrodes with very high surface area. The activity of such structures is found to be many times higher than that of conventional solid oxide fuel cell anodes. From the second study, carried out at lower temperatures, we observe hydrogen diffusion through thin-film Pt as a critical step in its electro-oxidation in fuel cells based on proton conducting electrolytes. Accordingly, structures which expose a continuous layer of Pt on a high surface-area scaffold of the electrolyte material are pursued and found to dramatically enhance Pt utilization relative to more conventional anodes with isolated Pt nanoparticles. These investigations demonstrate the power of fundamental mech


Hester, Glenda