Iron-only hydrogenases: a functional artificial H-cluster
Lead Research Organisation:
University of East Anglia
Department Name: Chemistry
Abstract
Converting protons to hydrogen at an electrode and its reverse getting electricity from hydrogen are reactions of fundamental importance to a hydrogen economy. Platinum is currently the best catalyst for both obtaining hydrogen as a fuel from water by electrolysis and using hydrogen to produce electricity by oxidising it in fuel cells. It is an expensive metal and in the long term is likely unsustainable with respect to demand from an expanding hydrogen economy . Issues relating to security of supply have also been raised. Nature carries out the same reactions using hydrogenase enzymes to catalyse the production or use of hydrogen in bacteria and algae . The machinery at the heart of one of these enzymes is a cluster of iron and sulfur atoms (abundant elements) known as the H-cluster. We are addressing the question 'can we make new materials based on nature's blueprint to replace platinum in fuel cells?' So far we and others have shown that structures closely similar to the catalytic centre of the enzyme can be synthesised. However these have proved poor catalysts, in part because the artifical structures have an 'extra' molecule of carbon monoxide attached to one of the iron atom and this 'blocks' its reaction with hydrogen or protons. This project sets out to build a functioning H-cluster. This will both help us to develop our understanding of how the biological catalysis works and may provide lead materials of technological relevance.
Technical Summary
The active site of the iron-only hydrogenases,the H-cluster, is comprised of a diiron unit linked to a 4F4S cluster by a cysteinyl bridge.The aim of the project is to construct a functional artificial H-cluster. Specifically, a subsite-cubane assembly capable of catalysing the reversible oxidation of molecular hydrogen / reduction of protons. Ideally the system should operate at diffusion controlled rates at potentials not far removed from the equilibrium potential of the H+/H2 couple at moderate pH. The construction of such an assembly will provide a means of probing the electronic interplay and mechanistic roles of the conjoined subsite and cubane components which comprises the biological H-cluster. This will contribute both to understanding how the iron-only hydrogenases work and to the design of new materials for catalysing this technologically important interconversion. The approach will be to build on recent work where we have shown that by using active thioesters it is possible to link diiron subsites to cubane clusters and so construct the FeS framework of the H-cluster.
People |
ORCID iD |
Christopher Pickett (Principal Investigator) |
Publications
Wright J
(2014)
Bioinspired Catalysis - Metal-Sulfur Complexes
Kaziannis S
(2010)
Femtosecond to microsecond photochemistry of a [FeFe]hydrogenase enzyme model compound.
in The journal of physical chemistry. B
Kaur A
(2014)
Anode modification to improve the performance of a microbial fuel cell volatile fatty acid biosensor
in Sensors and Actuators B: Chemical
Kaziannis S
(2011)
The role of CN and CO ligands in the vibrational relaxation dynamics of model compounds of the [FeFe]-hydrogenase enzyme.
in Physical chemistry chemical physics : PCCP
Wright J
(2010)
The Third Hydrogenase: More Natural Organometallics
in Organometallics
Jablonskyte A
(2011)
Paramagnetic bridging hydrides of relevance to catalytic hydrogen evolution at metallosulfur centers.
in Journal of the American Chemical Society
Jablonskyte A
(2014)
Electronic Control of the Protonation Rates of Fe-Fe Bonds
in Journal of the American Chemical Society
Hunt NT
(2016)
Detection of Transient Intermediates Generated from Subsite Analogues of [FeFe] Hydrogenases.
in Inorganic chemistry
Wright JA
(2011)
Protonation of [FeFe]-hydrogenase sub-site analogues: revealing mechanism using FTIR stopped-flow techniques.
in Faraday discussions
Frederix PW
(2012)
Encapsulating [FeFe]-hydrogenase model compounds in peptide hydrogels dramatically modifies stability and photochemistry.
in Dalton transactions (Cambridge, England : 2003)
Description | Converting protons to hydrogen at an electrode and its reverse getting electricity from hydrogen are reactions of fundamental importance to a hydrogen economy. Platinum is currently the best catalyst for both obtaining hydrogen as a fuel from water by electrolysis and using hydrogen to produce electricity by oxidising it in fuel cells. It is an expensive metal and in the long term is likely unsustainable with respect to demand from an expanding hydrogen economy . Issues relating to security of supply have also been raised. Nature carries out the same reactions using hydrogenase enzymes to catalyse the production or use of hydrogen in bacteria and algae . The machinery at the heart of one of these enzymes is a cluster of iron and sulfur atoms (abundant elements) known as the H-cluster. We have addressed the question 'can we make new materials based on nature's blueprint to replace platinum in fuel cells?' So far we and others have shown that structures closely similar to the catalytic centre of the enzyme can be synthesised. However these have proved poor catalysts, in part because the artifical structures have an 'extra' molecule of carbon monoxide attached to one of the iron atom and this 'blocks' its reaction with hydrogen or protons. This project set out to understand basic design principles of electron and proton transfer to artificial and to build build a functioning 'H-cluster' analogues. Much new chemistry has been learnt, especially relevant to the role of hydrides. |
Exploitation Route | Understanding structural and mechanistic principles related to the functioning of the hydrogenases. |
Sectors | Energy |
Description | Photophysical studies of syntheticanalogues of hydrogenase active sites |
Organisation | University of Strathclyde |
Country | United Kingdom |
Sector | Academic/University |
PI Contribution | Synthesis of artificial active sites related to the hydrogenases |
Collaborator Contribution | Detailed photophysical studies of artificial hydrogenase active sites. |
Impact | Several refereed papers. Physics/Chemistry |
Start Year | 2008 |