NSF-DFG EChem: CAS: Mechanistic Interrogation of Electrocatalytic Hydrogen Evolution by an Artificial Hydrogenase

Ohio State University, The, Columbus OH

Investigators

Abstract

With support from the NSF Division of Chemistry, Hannah Shafaat of Ohio State University and collaborators at the Technical University of Munich and the Max Planck Institute for Chemical Energy Conversion will develop and characterize optimized catalytic systems for production of hydrogen gas from water. The development of catalysts that can efficiently convert electrochemical energy into sustainable fuels such as H2 represents a critical obstacle that must be overcome in order to replace fossil fuels with environmentally friendly alternatives. Nature’s catalysts for hydrogen conversion, enzymes known as hydrogenases, exhibit an unparalleled degree of activity; despite global efforts, no sustainable synthetic catalyst has yet been developed that is comparable in rate and efficiency to the natural hydrogenases. While practical application of the natural systems is limited, decades of study on hydrogenases have provided substantial understanding of the enzyme properties as well as the catalytic mechanism, revealing key features that are necessary for function. These general design principles will be applied to construct a highly efficient catalytic system for electrochemical energy conversion. Through this project, graduate students from all three teams will combine their expertise across areas of biochemistry, inorganic chemistry, spectroscopy, and electrochemistry, building interdisciplinary international collaborations. The insight obtained from these fundamental studies is expected to be broadly applicable to the generation of scalable materials for electrochemical energy storage, including water oxidation, nitrogen fixation, and CO2 reduction, with potential for global socioeconomic impact. Students and postdoctoral scholars conducting the research will experience international exchange, including a workshop involving the entire project team. This approach to catalyst design from the group of Hannah Shafaat at Ohio State University and her German collaborators focuses on the development of a robust, artificial hydrogenase electrocatalyst. Using a model metalloenzyme as a well-defined scaffold, the team will incorporate select molecular complexes as intramolecular electron relays to functionally model the native redox-active cofactors and establish their roles in electrocatalysis. The hybrid enzyme will be anchored onto an electrode surface, designed to act as an electron transfer partner, and system variables that impact interfacial charge transfer will be probed. The specific objectives of the research program are to (i) design and implement strategies for integration of the individual components; (ii) to apply novel in situ spectro-electrochemical studies to interrogate the mechanism of H2 evolution by the hybrid constructs and (iii) to optimize these systems by tuning secondary and outer sphere properties to enhance catalytic efficiencies. By identifying the role that each component plays in catalysis, sluggish steps will be improved upon and unproductive or degradative pathways can be eradicated to systematically improve the catalytic system. This research was funded under the NSF-DFG Lead Agency Activity in Electrosynthesis and Electrocatalysis (NSF-DFG EChem) opportunity NSF 20-578. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.