Events & Seminars > Event Details

Where:

4:00 pm
Room 304, Chemistry Building

Design of Molecular Electrocatalysts for the Production and Oxidation of Hydrogen: Shoving Protons Around With Proton Relays

Speaker:

Dr. Morris Bullock
Pacific Northwest National Laboratory

Hosted by: Professor Brent Gunnoe

Solar and wind are carbon-neutral, sustainable energy sources, but their intermittent nature requires reliable energy storage. Catalysts that efficiently interconvert between electrical energy and chemical bonds (fuels) are needed for sustainable, secure energy in the future.  Hydrogenase enzymes in nature based on iron and/or nickel catalyze the oxidation of H2 and the reverse, production of H2 by reduction of protons. Electrocatalysts based on inexpensive, earth-abundant metals (“Cheap Metals for Noble Tasks”) are needed since low-temperature fuel cells generally use platinum, an expensive, precious metal. Biologically inspired synthetic complexes studied in our lab incorporate pendant amines into the second coordination sphere of metal complexes.  The amines function as proton relays, facilitating intramolecular and intermolecular proton mobility.

We are developing nickel(II) complexes with pendant amines that catalyze the oxidation of H2 at 1 atm. A related series of Ni(II) complexes have been studied in detail for electrocatalytic production of H2 by reduction of protons.  Turnover frequencies greater than 100,000 s-1 have been observed, though often at a high overpotential. Iron complexes with pendant amines on the diphosphine ligand are also being studied, showing that it is possible to rationally design catalysts based on abundant, inexpensive metals as alternatives to precious metals. Organometallic Fe(II) complexes derived from CpFe(diphosphine)H, with pendant amines in the diphosphine ligands, mimic the reactivity of [FeFe]-hydrogenase enzymes, leading to new iron catalysts for oxidation of H2. Mn(I) complexes containing pendant amines on the diphosphine ligand exhibit unusually fast reversible heterolytic cleavage of H2.