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Title: Merging [FeFe]-Hydrogenases with Materials and Nanomaterials as Biohybrid Catalysts for Solar H2 Production

Abstract

The catalysts commonly used for the H{sub 2} producing reaction in artificial solar systems are typically platinum or particulate platinum composites. Biological catalysts, the hydrogenases, exist in a wide-variety of microbes and are biosynthesized from abundant, non-precious metals. By virtue of a unique catalytic metallo-cluster that is composed of iron and sulfur, [FeFe]-hydrogenases are capable of catalyzing H{sub 2} production at turnover rates of millimoles-per-second. In addition, these biological catalysts possess some of the characteristics that are desired for cost-effective solar H{sub 2} production systems, high solubilities in aqueous solutions and low activation energies, but are sensitive to CO and O{sub 2}. We are investigating ways to merge [FeFe]-hydrogenases with a variety of organic materials and nanomaterials for the fabrication of electrodes and biohybrids as catalysts for use in artificial solar H{sub 2} production systems. These efforts include designs that allow for the integration of [FeFe]-hydrogenase in dye-solar cells as models to measure solar conversion and H{sub 2} production efficiencies. In support of a more fundamental understanding of [FeFe]-hydrogenase for these and other applications the role of protein structure in catalysis is being investigated. Currently there is little known about the mechanism of how these and other enzymes couple multi-electronmore » transfer to proton reduction. To further the mechanistic understanding of [FeFe]-hydrogenases, structural models for substrate transfer are being used to create enzyme variants for biochemical analysis. Here results are presented on investigations of proton-transfer pathways in [FeFe]-hydrogenase and their interaction with single-walled carbon nanotubes.« less

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
940622
DOE Contract Number:
AC36-99-GO10337
Resource Type:
Journal Article
Resource Relation:
Journal Name: Solar Hydrogen and Nanotechnology II; Journal Volume: 6650
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; 14 SOLAR ENERGY; 36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; AQUEOUS SOLUTIONS; CARBON; CATALYSIS; CATALYSTS; ELECTRODES; ENZYMES; FABRICATION; HYDROGEN; HYDROGENASES; IRON; NANOTUBES; PARTICULATES; PLATINUM; PROTEIN STRUCTURE; PROTONS; SOLAR SYSTEM; STRUCTURAL MODELS; SUBSTRATES; SULFUR; Basic Sciences

Citation Formats

King, P. W., Svedruzic, D., Hambourger, M., Gervaldo, M., McDonald, T., Blackburn, J., Heben, M., Gust, D., Moore, A. L., Moore, T. A., and Ghirardi, M. L.. Merging [FeFe]-Hydrogenases with Materials and Nanomaterials as Biohybrid Catalysts for Solar H2 Production. United States: N. p., 2007. Web. doi:10.1117/12.736556.
King, P. W., Svedruzic, D., Hambourger, M., Gervaldo, M., McDonald, T., Blackburn, J., Heben, M., Gust, D., Moore, A. L., Moore, T. A., & Ghirardi, M. L.. Merging [FeFe]-Hydrogenases with Materials and Nanomaterials as Biohybrid Catalysts for Solar H2 Production. United States. doi:10.1117/12.736556.
King, P. W., Svedruzic, D., Hambourger, M., Gervaldo, M., McDonald, T., Blackburn, J., Heben, M., Gust, D., Moore, A. L., Moore, T. A., and Ghirardi, M. L.. Mon . "Merging [FeFe]-Hydrogenases with Materials and Nanomaterials as Biohybrid Catalysts for Solar H2 Production". United States. doi:10.1117/12.736556.
@article{osti_940622,
title = {Merging [FeFe]-Hydrogenases with Materials and Nanomaterials as Biohybrid Catalysts for Solar H2 Production},
author = {King, P. W. and Svedruzic, D. and Hambourger, M. and Gervaldo, M. and McDonald, T. and Blackburn, J. and Heben, M. and Gust, D. and Moore, A. L. and Moore, T. A. and Ghirardi, M. L.},
abstractNote = {The catalysts commonly used for the H{sub 2} producing reaction in artificial solar systems are typically platinum or particulate platinum composites. Biological catalysts, the hydrogenases, exist in a wide-variety of microbes and are biosynthesized from abundant, non-precious metals. By virtue of a unique catalytic metallo-cluster that is composed of iron and sulfur, [FeFe]-hydrogenases are capable of catalyzing H{sub 2} production at turnover rates of millimoles-per-second. In addition, these biological catalysts possess some of the characteristics that are desired for cost-effective solar H{sub 2} production systems, high solubilities in aqueous solutions and low activation energies, but are sensitive to CO and O{sub 2}. We are investigating ways to merge [FeFe]-hydrogenases with a variety of organic materials and nanomaterials for the fabrication of electrodes and biohybrids as catalysts for use in artificial solar H{sub 2} production systems. These efforts include designs that allow for the integration of [FeFe]-hydrogenase in dye-solar cells as models to measure solar conversion and H{sub 2} production efficiencies. In support of a more fundamental understanding of [FeFe]-hydrogenase for these and other applications the role of protein structure in catalysis is being investigated. Currently there is little known about the mechanism of how these and other enzymes couple multi-electron transfer to proton reduction. To further the mechanistic understanding of [FeFe]-hydrogenases, structural models for substrate transfer are being used to create enzyme variants for biochemical analysis. Here results are presented on investigations of proton-transfer pathways in [FeFe]-hydrogenase and their interaction with single-walled carbon nanotubes.},
doi = {10.1117/12.736556},
journal = {Solar Hydrogen and Nanotechnology II},
number = ,
volume = 6650,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Shewanella oneidensis MR-1 encodes both a [NiFe]- and an [FeFe]-hydrogenase. While the output of these proteins has been characterized in mutant strains expressing only one of the enzymes, the contribution of each to H2 synthesis in the wild-type organism is not clear. Here we use stable isotope analysis of H2 in the culture headspace, along with transcription data and measurements of the concentrations of gases in the headspace, to characterize H2 production in the wild-type strain. After most of the O2 in the headspace had been consumed, H2 was produced and then consumed by the bidirectional [NiFe]-hydrogenase. Once the culturesmore » were completely anaerobic, a new burst of H2 synthesis catalyzed by both enzymes took place. Our data is consistent with the hypothesis that at this point in the culture cycle, a pool of electrons is shunted toward both hydrogenases in the wild-type organism, but that in the absence of one of the hydrogenases, the flux is redirected to the available enzyme. To our knowledge, this is the first use of stable isotope analysis of a metabolic product to elucidate substrate flux through two alternative enzymes in the same cellular system.« less
  • Hydrogenases catalyze the reversible formation of H2, and they are key enzymes in the biological cycling of H2. H isotopes should be a very useful tool in quantifying proton trafficking in biological H2 production processes, but there are several obstacles that have thus far limited the use of this tool. In this manuscript, we describe a new method that overcomes some of these barriers and is specifically designed to measure isotopic fractionation during enzyme-catalyzed H2 evolution. A key feature of this technique is that purified hydrogenases are employed, allowing precise control over the reaction conditions and therefore a high levelmore » of precision. A custom-designed high-throughput gas chromatography-isotope ratio mass spectrometer is employed to measure the isotope ratio of the H2. Using this method, we determined that the fractionation factor of H2 production by the [NiFe]-hydrogenase from Desulfivibrio fructosovran is 0.27. This result indicates that, as expected, protons are highly favored over deuterons during H2 evolution. Potential applications of this new method are discussed.« less
  • The Clostridium acetobutylicum [FeFe]-hydrogenase HydA has been investigated as a hydrogen production catalyst in a photoelectrochemical biofuel cell. Hydrogenase was adsorbed to pyrolytic graphite edge and carbon felt electrodes. Cyclic voltammograms of the immobilized hydrogenase films reveal cathodic proton reduction and anodic hydrogen oxidation, with a catalytic bias toward hydrogen evolution. When corrected for the electrochemically active surface area, the cathodic current densities are similar for both carbon electrodes, and 40% of those obtained with a platinum electrode. The high surface area carbon felt/hydrogenase electrode was subsequently used as the cathode in a photoelectrochemical biofuel cell. Under illumination, this devicemore » is able to oxidize a biofuel substrate and reduce protons to hydrogen. Similar photocurrents and hydrogen production rates were observed in the photoelectrochemical biofuel cell using either hydrogenase or platinum cathodes.« less
  • We have developed complexes of CdS nanorods capped with 3-mercaptopropionic acid (MPA) and Clostridium acetobutylicum [FeFe]-hydrogenase I (CaI) that photocatalyze reduction of H{sup +} to H{sub 2} at a CaI turnover frequency of 380-900 s{sup -1} and photon conversion efficiencies of up to 20% under illumination at 405 nm. In this paper, we focus on the compositional and mechanistic aspects of CdS:CaI complexes that control the photochemical conversion of solar energy into H{sub 2}. Self-assembly of CdS with CaI was driven by electrostatics, demonstrated as the inhibition of ferredoxin-mediated H{sub 2} evolution by CaI. Production of H{sub 2} by CdS:CaImore » was observed only under illumination and only in the presence of a sacrificial donor. We explored the effects of the CdS:CaI molar ratio, sacrificial donor concentration, and light intensity on photocatalytic H{sub 2} production, which were interpreted on the basis of contributions to electron transfer, hole transfer, or rate of photon absorption, respectively. Each parameter was found to have pronounced effects on the CdS:CaI photocatalytic activity. Specifically, we found that under 405 nm light at an intensity equivalent to total AM 1.5 solar flux, H{sub 2} production was limited by the rate of photon absorption ({approx}1 ms{sup -1}) and not by the turnover of CaI. Complexes were capable of H{sub 2} production for up to 4 h with a total turnover number of 106 before photocatalytic activity was lost. This loss correlated with inactivation of CaI, resulting from the photo-oxidation of the CdS capping ligand MPA.« less