Theoretical design of hydrogenase-inspired molecular hydrogen production catalysts through calculated free-energy landscapes and coupled Pourbaix diagrams

James T. Muckerman, Yolanda A. Small, Jonathan H. Skone, Daniel L. DuBois, Etsuko Fujita

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Hydrogen production using a molecular catalyst involves a sequence of redox steps (proton transfer (PT), electron transfer (ET), or proton-coupled electron-transfer (PCET)) interspersed with thermal reactions (oxidative addition of a proton to a reduced metal center or heterolytic association of a proton and a hydride ion). This sequence of reaction steps requires a relatively flat free-energy landscape over the entire cycle for an efficient catalytic process. In designing a good catalyst, it becomes essential to ensure that the key intermediates at each reaction step be the dominant form (e.g., protonated or unprotonated) of that species at the pH of the solution. Consideration of this issue may be termed "proton management" because it seeks to regulate the supply of protons to optimize the overall reaction kinetics. It becomes an important issue when we attempt to link individual chemical reactions into an integrated system of reactions for optimal throughput (i.e., turnover). We describe a new approach to PCET in fuel production using proton management to control overall reaction kinetics, enabling the rational design of catalysts that can function in aqueous solution. Some design principles for effective DuBois hydrogenase-model catalysts for hydrogen production can be elucidated through Pourbaix diagrams for the PCET steps that are coupled by the thermal reaction steps that take the system from one diagram to another, then back again. These design principles can be satisfied to some extent by the choice of metal and ligands, and can be explored efficiently by theoretical calculations.

Original languageEnglish
Title of host publicationAmerican Chemical Society - 238th National Meeting and Exposition, ACS 2009, Abstracts of Scientific Papers
Publication statusPublished - Dec 1 2009
Event238th National Meeting and Exposition of the American Chemical Society, ACS 2009 - Washington, DC, United States
Duration: Aug 16 2009Aug 20 2009

Publication series

NameACS National Meeting Book of Abstracts
ISSN (Print)0065-7727

Other

Other238th National Meeting and Exposition of the American Chemical Society, ACS 2009
CountryUnited States
CityWashington, DC
Period8/16/098/20/09

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ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

Cite this

Muckerman, J. T., Small, Y. A., Skone, J. H., DuBois, D. L., & Fujita, E. (2009). Theoretical design of hydrogenase-inspired molecular hydrogen production catalysts through calculated free-energy landscapes and coupled Pourbaix diagrams. In American Chemical Society - 238th National Meeting and Exposition, ACS 2009, Abstracts of Scientific Papers (ACS National Meeting Book of Abstracts).