Poster abstracts

Poster number 114 submitted by Jeffrey Slater

Electrochemical Hydrogen Generation using a Protein-Based Catalyst

Jeffrey W. Slater (OSBP, The Ohio State University), Haleigh A. Monaco (Department of Chemistry and Biochemistry, University of Colorado Boulder), Alex J. Leveto (Department of Chemistry and Biochemistry, The Ohio State University), Regina E. Trevino (Department of Chemistry and Biochemistry, The Ohio State University)

Abstract:
The energy crisis of the last decade has led to new and innovative approaches to combat this pressing issue. One leading candidate as an alternative fuel is hydrogen due to its derivability from water, its high energy density, and its status as a clean fuel. However, the current methods for hydrogen production rely on precious metal catalysts and thus are not economically feasible to replace fossil fuels. A promising alternative for catalytic hydrogen generation is through the use of the hydrogenase enzymes, which take advantage of earth-abundant metals such as nickel and iron. Hydrogenases, however, are limited by their intolerance to oxygen, sensitivity to temperature and pH, and the complexity of their biosynthesis, thus limiting industrial applicability.
We present a functional mimic of the [NiFe]-hydrogenases based on a nickel-substituted rubredoxin (NiRd) protein. NiRd is capable of light-initiated and solution-phase hydrogen production and demonstrates high electrocatalytic activity using protein film voltammetry. Utilizing analytical expressions developed for hydrogenase enzymes, maximum turnover frequencies of approximately 20−100 s−1 at 4 °C are obtained with an overpotential of 540 mV. However, unlike the native hydrogenase, NiRd remains catalytically active and relatively unaffected under atmospheres of O2 and H2. Recent work has been aimed at developing novel, site-selective methods for covalent attachment of NiRd to a modified carbon electrode and quantification of active catalyst density on the electrode surface, a currently difficult process for most electrocatalytic proteins. This bioconjugation to an electrode surface allows for studies of the electrocatalytic process that are typically prohibitive using standard protein film electrochemistry. Through further studies and protein engineering, this rubredoxin-based enzyme is an excellent platform to build upon towards sustainable fuel generation.

References:
Slater, J. W.; Shafaat, H. S. The Journal of Physical Chemistry Letters 2015, 3731–3736.
Slater, J. W.; Marguet, S. C.; et al. Inorganic Chemistry 2017, 56 (7), 3926–3938.

Keywords: Metalloprotein, Hydrogen, Electrochemistry