Resnick Institute Seminar

Please join us for a seminar given by Resnick Postdoctoral Scholar James D. Blakemore & Resnick Graduate Research Fellow Samantha I. Johnson

Blakemore's talk: "Combining Protons and Electrons to Efficiently Generate H₂ from Renewable Resources"

Efficient generation of hydrogen from renewable resources requires development of catalysts that avoid deep wells and high barriers. Information about such features can be obtained by chemical characterization of catalytic intermediates, but few have been observed to date, even in "simple" molecular model compounds. In this presentation, I will describe the characterization of such an intermediate species formed en route to hydrogen evolution. This intermediate, obtained by treatment of Cp*Rh(bpy) (Cp* = η⁵-pentamethylcyclcopentadienyl; bpy = κ²-2,2´-bipyridyl) with acid, is not a hydride species but rather bears the proton at a remote ligand site. Appealingly, the preserved reduced Rh center can readily be protonated, leading to evolution of H₂. Recent results, including spectroscopic studies of the isolated intermediate, will be discussed.

Johnson's talk: "From the Background to Center Stage: The Unexpected Role of "Innocent" Ligands in Hydrogen Evolution Catalysis and Surface Attachment"

One challenge to higher market penetration of solar power is the storage of harvested energy in a useful form. One proposed storage technique is generation of solar fuels like hydrogen (H₂). Generation of H₂ involves the combination of two protons from water and two electrons energized by light. A metal catalyst often aids this reaction. However, the nature of the elementary steps leading to H–H formation with most catalysts is not clear, as chemical characterization of intermediates in the catalytic reaction has been difficult to obtain. Additionally, attachment of catalysts to electrodes introduces further ambiguities, making rational stability or activity improvements in such systems nearly impossible. Atomistic computational modeling techniques like density functional theory (DFT) are a useful tool for understanding the mechanism by which hydrogen is evolved, as it provides a detailed picture of the individual steps involved. This talk will largely focus on how one catalyst, Cp*Rh(bpy) (Cp* = η⁵-pentamethylcyclcopentadienyl; bpy = κ²-2,2´-bipyridyl), relies on unexpected ligand-centered processes during catalysis, and how these processes affect the catalytic mechanism and stability of the system.