A5003568078- Metalloenzymes and iron-sulfur proteins
- Electrocatalysts for Energy Conversion
- Advanced battery technologies research
- Enzyme Catalysis and Immobilization
- Ammonia Synthesis and Nitrogen Reduction
- Asymmetric Hydrogenation and Catalysis
- Electrochemical sensors and biosensors
- Hydrogen Storage and Materials
- Nanomaterials for catalytic reactions
- Chemical Reactions and Isotopes
- Electrochemical Analysis and Applications
- CO2 Reduction Techniques and Catalysts
- Microbial Fuel Cells and Bioremediation
- Innovative Microfluidic and Catalytic Techniques Innovation
- Catalysis for Biomass Conversion
- Amino Acid Enzymes and Metabolism
- Pharmacogenetics and Drug Metabolism
- Fuel Cells and Related Materials
- Metal-Catalyzed Oxygenation Mechanisms
- Advanced Photocatalysis Techniques
- Microbial Metabolic Engineering and Bioproduction
- Molecular Junctions and Nanostructures
- Mass Spectrometry Techniques and Applications
- Photosynthetic Processes and Mechanisms
- Catalysis and Hydrodesulfurization Studies
University of Oxford
2016-2025
Science Oxford
2014-2021
Delft University of Technology
2020
Utah State University
2010
Northwestern University
2010
Virginia Tech
2010
Humboldt-Universität zu Berlin
2005-2008
University of Nebraska–Lincoln
2007
Max Planck Society
2006
Technische Universität Berlin
2005
Green algae such as Chlamydomonas reinhardtii synthesize an [FeFe] hydrogenase that is highly active in hydrogen evolution. However, the extreme sensitivity of hydrogenases to oxygen presents a major challenge for exploiting these organisms achieve sustainable photosynthetic production. In this study, mechanism inactivation Cr HydA1 from C. has been investigated. X-ray absorption spectroscopy shows reaction with results destruction [4Fe-4S] domain site H-cluster while leaving di-iron (2Fe H...
Abstract Optoelectronic devices based on hybrid halide perovskites have shown remarkable progress to high performance. However, despite their apparent success, there remain many open questions about intrinsic properties. Single crystals are often seen as the ideal platform for understanding limits of crystalline materials, and recent reports rapid, high-temperature crystallization single should enable a variety studies. Here we explore mechanism this find that it is due reversible changes in...
The sluggish kinetics of oxygen reduction to water remains a significant limitation in the viability proton-exchange-membrane fuel cells, yet details four-electron reaction remain elusive. Herein, we apply situ infrared spectroscopy probe surface chemistry commercial carbon-supported Pt nanoparticle catalyst during reduction. IR spectra show potential-dependent appearance adsorbed superoxide and hydroperoxide intermediates on Pt. This strongly supports an associative pathway for Analysis...
Abstract Renewable fuel generation is essential for a low carbon footprint economy. Thus, over the last five decades, significant effort has been dedicated towards increasing performance of solar fuels generating devices. Specifically, to hydrogen efficiency photoelectrochemical cells progressed steadily its fundamental limit, and faradaic valuable products in CO 2 reduction systems increased dramatically. However, there are still numerous scientific engineering challenges that must be...
Abstract Diverse aerobic bacteria use atmospheric H 2 as an energy source for growth and survival 1 . This globally significant process regulates the composition of atmosphere, enhances soil biodiversity drives primary production in extreme environments 2,3 Atmospheric oxidation is attributed to uncharacterized members [NiFe] hydrogenase superfamily 4,5 However, it remains unresolved how these enzymes overcome extraordinary catalytic challenge oxidizing picomolar levels amid ambient poison O...
Use of hydrogen in fuel cells requires catalysts that are tolerant to oxygen and able function the presence poisons such as carbon monoxide. Hydrogen-cycling widespread bacterial world form hydrogenases, enzymes with unusual active sites composed iron, or nickel buried within protein. We have established membrane-bound hydrogenase from β-proteobacterium Ralstonia eutropha H16, when adsorbed at a graphite electrode, exhibits rapid electrocatalytic oxidation is completely unaffected by...
A new strategy is described for comparing, quantitatively, the ability of hydrogenases to tolerate exposure O2 and anoxic oxidizing conditions. Using protein film voltammetry, inherent sensitivities these challenges (thermodynamic potentials rates reactions) have been measured enzymes from a range mesophilic microorganisms. In absence O2, all undergo reversible inactivation at various above that H+/H2 redox couple, H2 oxidation activities are thus limited characteristic "potential windows"....
The Ni-containing carbon monoxide dehydrogenase I from Carboxydothermus hydrogenoformans adsorbed on a pyrolytic graphite "edge" electrode catalyzes rapid CO2/CO interconversions at the thermodynamic potential.
Abstract A novel in situ IR spectroscopic approach is demonstrated for the characterization of hydrogenase during catalytic turnover. E. coli 1 (Hyd‐1) adsorbed on a high surface‐area carbon electrode and subjected to same electrochemical control efficient supply substrate as protein film electrochemistry spectral acquisition. The spectra reveal that active site state known Ni‐L, observed other NiFe hydrogenases only under illumination or at cryogenic temperatures, can be generated...
Abstract Enzymes dependent on nicotinamide cofactors are important components of the expanding range asymmetric synthetic techniques. New challenges in catalysis arising field deuterium labelling, where compounds bearing ( 2 H) atoms at chiral centres becoming increasingly desirable targets for pharmaceutical and analytical chemists. However, utilisation NADH-dependent enzymes H-labelling is not straightforward, owing to difficulties supplying a suitably isotopically-labelled cofactor ([4-...
The cycling between active and inactive states of the catalytic center [NiFe]-hydrogenase from Allochromatium vinosum has been investigated by dynamic electrochemical techniques. Adsorbed on a rotating disk pyrolytic graphite "edge" electrode, enzyme is highly electroactive: this allows precise manipulations complex redox chemistry facilitates quantitative measurements interconversions oxidized form Nir* (also called Ni−B or "ready") as functions pH, H2 partial pressure, temperature,...
We demonstrate an extreme test of O2 tolerance for a biological hydrogen-cycling catalyst: the generation electricity from just 3% H2 released into still, ambient air using open fuel cell comprising anode modified with unusual hydrogenase Ralstonia metallidurans CH34, that oxidizes trace in atmospheric O2, connected via film electrolyte to cathode fungal reductase, laccase.
Knallgas bacteria such as certain Ralstonia spp. are able to obtain metabolic energy by oxidizing trace levels of H2 using O2 the terminal electron acceptor. The [NiFe] hydrogenases produced these organisms unusual in their ability oxidize presence O2, which is a potent inactivator most through attack at active site. To probe origin this tolerance, we conducted study on membrane-bound hydrogenase from eutropha H16 and that closely related organism metallidurans CH34, was purified new...
A molecular wire is used to connect two proteins through their physiologically relevant redox cofactors facilitate direct electron transfer. Photosystem I (PS I) and an [FeFe]-hydrogenase (H(2)ase) serve as the test bed for this new technology. By tethering a photosensitizer with hydrogen-evolving catalyst, attached by Fe-S coordination bonds between F(B) iron-sulfur cluster of PS distal H(2)ase, we assayed transfer components via light-induced hydrogen generation. These hydrogen-producing...
Studies have been carried out to establish the ability of O2-tolerant membrane-bound [NiFe] hydrogenases (MBH) from Ralstonia sp. catalyze H2 production in addition oxidation. These are not noted for H2-evolution activity, and this is partly due strong product inhibition. However, when adsorbed on a rotating disk graphite electrode enzymes produce efficiently, provided continuously removed by rapidly flowing N2 through gastight electrochemical cell. Electrocatalytic proceeds with minimal...
Despite extensive studies on [NiFe]-hydrogenases, the mechanism by which these enzymes produce and activate H2 so efficiently remains unclear. A well-known EPR-active state produced under known as Ni-C is assigned a Ni(III)-Fe(II) species with hydrido ligand in bridging position between two metals. It has long been that low-temperature photolysis of yields distinctive states, collectively termed Ni-L, are attributed to migration bridging-H proton; however, Ni-L mainly regarded an artifact no...
The oxidation of adsorbed CO is a key reaction in electrocatalysis. It has been studied extensively on both extended model surfaces and nanoparticles; however, correlation between the two far from simple. Molecular insight into often provided using situ IR spectroscopy; practical challenges mean studies nanoparticles have yet to provide same level detail as those surfaces. Here we use new approach spectroscopy study mechanism adlayer commercial carbon-supported Pt catalyst. We observe...
The catalytic reduction of hydrazine (N2H4) to ammonia by a β-98Tyr→His MoFe protein in the absence Fe or ATP is reported. N2 other substrates (e.g., hydrazine, protons, acetylene) nitrogenase normally requires transient association two component proteins, and protein. protein, with bound MgATP molecules, transfers one electron during each association, coupled hydrolysis MgATP. All substrate reactions catalyzed require delivery electrons We report that when single amino acid within (β-98Tyr)...
We describe a new approach to selective H2-driven hydrogenation that exploits sequence of enzymes immobilised on carbon particles. used catalyst system comprised alcohol dehydrogenase, hydrogenase and an NAD+ reductase black demonstrate greater than 98 % conversion acetophenone phenylethanol. Oxidation H2 by the provides electrons through for reduction recycle NADH cofactor required dehydrogenase. This biocatalytic operates over pH range 6-8 or in un-buffered water, can function at low...