Recent advances in Ni-based bio-inspired catalysts obtained in the Energy Frontier Research Center (EFRC) for Molecular Electrocatalysis at the Pacific Northwest National Laboratory demonstrated the possibility of cleaving H2 or generating H2 heterolytically with efficiency superior to that of hydrogenase enzymes. In these catalysts the transformation between H2 and protons proceeds via an interplay between proton, hydride and electron transfer steps and involves the interaction of a dihydrogen molecule with both a Ni(II) center and with pendant amine bases incorporated in a six-membered ring, which act as proton relays. By using ab initio molecular dynamics, free energy calculations and microkinetic modeling, we have carried out an exhaustive characterization of these molecular catalysts. It will be shown that the metal center and the pendant amine act as a frustrated Lewis acid/base pairs, making the heterolytic H2 bond cleavage or formation facile processes. A detailed microkinetic modeling of the catalytic cycle reveals the importance of precisely controlled delivery of protons to avoid catalytically inefficient pathways. Toward the rational design of catalysts with optimal rates and overpotentials, we are developing linear free energy relationships, based on extensive ab initio thermodynamic and kinetic data, to be employed in a theoretically driven refinement of catalysts using macrokinetic analysis.   Acknowledgments This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the US Department of Energy, Office of Science, Office of Basic Energy Sciences.

Toward the rational design of molecular electrocatalysts for production of H<sub>2</sub> and oxidation of H<sub>2</sub>

245th National Meeting (2013)

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Toward the rational design of molecular electrocatalysts for production of H2 and oxidation of H2

Toward the rational design of molecular electrocatalysts for production of H₂ and oxidation of H₂