[NiFe]Hydrogenase from <i>Citrobacter</i> sp. S‐77 Surpasses Platinum as an Electrode for H<sub>2</sub> Oxidation Reaction

Among sustainable alternatives to fossil fuel, proton exchange membrane fuel cells are promising devices that deliver electricity from hydrogen and oxygen, producing only water. The transformation of the fuel and oxidant however relies on rare‐metal catalysts. H2/O2 enzymatic biofuel cells thus emerge as sustainable biotechnological devices in which chemical catalysts are replaced by hydrogenases at the anode and multicopper oxidases at the cathode. This review discusses the recent breakthroughs and the limitations in all the components of H2/O2 biofuel cells: 1) Catalytic mechanisms involved in multicopper oxidases and hydrogenases, in addition to the new potential of enzymes from the biodiversity pool, which exhibit outstanding properties. 2) The molecular basis for oriented enzyme immobilization on the electrochemical interfaces as a prerequisite for a fast direct electron‐transfer rate. 3) The requirement for 3D networks to enhance current densities. 4) The production of H2 from biomass. 5) The history of H2/O2 biofuel cells and recent devices, which also highlights the remaining issues that will allow the use of such devices in low‐power applications.

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“…Except for the last EBFC reported by Ogo et al, [300] the calculated turnover of the incorporated Hase in the carbon materials (ca. 50 s…”

Section: Some Limitations Some Issuesmentioning

confidence: 91%

Biohydrogen for a New Generation of H₂/O₂ Biofuel Cells: A Sustainable Energy Perspective

et al. 2014

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“…24). In addition, fuel cells that use [NiFe] S77 as the anode catalyst exhibit 1.8 times higher electricity generating potential than Pt fuel cells [21]. In this way, [NiFe] S77 delivers greater capacity than Pt as an electrode catalyst in fuel cells.…”

Section: Application To Fuel Cellsmentioning

confidence: 99%

H2 and O2 activation by [NiFe]hydrogenases – Insights from model complexes

Ogo

2017

Coordination Chemistry Reviews

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“…15 Ogo and co-workers recently reported a new form of a [NiFe]-hydrogenase that was used in a fuel cell, with activity reported to surpass that of Pt. 16 The progress and challenges in the use of enzymes in fuel cells was reviewed by Armstrong and co-workers. 17 Progress toward earth-abundant catalysts continues to be moved forward by all of these diverse approaches.…”

Section: ■ Introductionmentioning

confidence: 99%

Molecular Electrocatalysts for Oxidation of Hydrogen Using Earth-Abundant Metals: Shoving Protons Around with Proton Relays

2015

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Sustainable, carbon-neutral energy is needed to supplant the worldwide reliance on fossil fuels in order to address the persistent problem of increasing emissions of CO2. Solar and wind energy are intermittent, highlighting the need to develop energy storage on a huge scale. Electrocatalysts provide a way to convert between electrical energy generated by renewable energy sources and chemical energy in the form of chemical bonds. Oxidation of hydrogen to give two electrons and two protons is carried out in fuel cells, but the typical catalyst is platinum, a precious metal of low earth abundance and high cost. In nature, hydrogenases based on iron or iron/nickel reversibly oxidize hydrogen with remarkable efficiencies and rates. Functional models of these enzymes have been synthesized with the goal of achieving electrocatalytic H2 oxidation using inexpensive, earth-abundant metals along with a key feature identified in the [FeFe]-hydrogenase: an amine base positioned near the metal. The diphosphine ligands P(R)2N(R')2 (1,5-diaza-3,7-diphosphacyclooctane with alkyl or aryl groups on the P and N atoms) are used as ligands in Ni, Fe, and Mn complexes. The pendant amines facilitate binding and heterolytic cleavage of H2, placing the hydride on the metal and the proton on the amine. The pendant amines also serve as proton relays, accelerating intramolecular and intermolecular proton transfers. Electrochemical oxidations and deprotonations by an exogeneous amine base lead to catalytic cycles for oxidation of H2 (1 atm) at room temperature for catalysts derived from [Ni(P(Cy)2N(R')2)2](2+), Cp(C6F5)Fe(P(tBu)2N(Bn)2)H, and MnH(P(Ph)2N(Bn)2)(bppm)(CO) [bppm = (PAr(F)2)2CH2]. In the oxidation of H2 catalyzed by [Ni(P(Cy)2N(R')2)2](2+), the initial product observed experimentally is a Ni(0) complex in which two of the pendant amines are protonated. Two different pathways can occur from this intermediate; deprotonation followed by oxidation occurs with a lower overpotential than the alternate pathway involving oxidation followed by deprotonation. The Mn cation [Mn(P(Ph)2N(Bn)2)(bppm)(CO)](+) mediates the rapid (>10(4) s(-1) at -95 °C), reversible heterolytic cleavage of H2. Obtaining the optimal benefit of pendant amines incorporated into the ligand requires that the pendant amine be properly positioned to interact with a M-H or M(H2) bond. In addition, ligands are ideally selected such that the hydride-acceptor ability of the metal and the basicity of a pendant are tuned to give low barriers for heterolytic cleavage of the H-H bond and subsequent proton transfer reactions. Using these principles allows the rational design of electrocatalysts for H2 oxidation using earth-abundant metals.

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[NiFe]Hydrogenase from Citrobacter sp. S‐77 Surpasses Platinum as an Electrode for H₂ Oxidation Reaction

Cited by 39 publications

References 23 publications

Biohydrogen for a New Generation of H₂/O₂ Biofuel Cells: A Sustainable Energy Perspective

Biohydrogen for a New Generation of H₂/O₂ Biofuel Cells: A Sustainable Energy Perspective

H2 and O2 activation by [NiFe]hydrogenases – Insights from model complexes

Molecular Electrocatalysts for Oxidation of Hydrogen Using Earth-Abundant Metals: Shoving Protons Around with Proton Relays

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[NiFe]Hydrogenase from Citrobacter sp. S‐77 Surpasses Platinum as an Electrode for H2 Oxidation Reaction

Cited by 39 publications

References 23 publications

Biohydrogen for a New Generation of H2/O2 Biofuel Cells: A Sustainable Energy Perspective

Biohydrogen for a New Generation of H2/O2 Biofuel Cells: A Sustainable Energy Perspective

H2 and O2 activation by [NiFe]hydrogenases – Insights from model complexes

Molecular Electrocatalysts for Oxidation of Hydrogen Using Earth-Abundant Metals: Shoving Protons Around with Proton Relays

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Product

Resources

About

[NiFe]Hydrogenase from Citrobacter sp. S‐77 Surpasses Platinum as an Electrode for H₂ Oxidation Reaction

Biohydrogen for a New Generation of H₂/O₂ Biofuel Cells: A Sustainable Energy Perspective

Biohydrogen for a New Generation of H₂/O₂ Biofuel Cells: A Sustainable Energy Perspective