Following Electroenzymatic Hydrogen Production by Rotating Ring–Disk Electrochemistry and Mass Spectrometry**

Khushvakov, Jaloliddin; Nussbaum, Robin; Cadoux, Cécile; Duan, Jifu; Stripp, Sven T.; Milton, Ross D.

doi:10.1002/anie.202100863

Cited by 8 publications

(9 citation statements)

References 37 publications

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“…Using double-layer capacitance, we determined the surface area enhancement offered by the use of nanoITO to be 19 on glassy carbon electrodes (Figure S5; note that this is an estimate due to differences in specific capacitances of nanoITO and the underlying GC electrode); accounting for this enhancement yields a corrected electrocatalytic current density that remains >38× the current densities typically obtained on GC electrodes (>6× those typically obtained on PGEs) (Figure S6), reflecting the importance of ITO for efficient [FeFe]-hydrogenase (CpI) immobilization and orientation (improved H 2 production is not only due to increased electrode surface area). Control experiments on O 2 -deactivated hydrogenase from Figure S7 show >80% current loss at −0.8 V vs. SHE, further confirming that the electrocatalytic current originates from hydrogenase and not the nanoITO electrode, consistent with previous O 2 -deactivation experiments . The bioelectrode performance was also investigated under H 2 to understand if nanoITO could influence the reversibility of CpI.…”

supporting

confidence: 82%

“…Control experiments on O 2 -deactivated hydrogenase from Figure S7 show >80% current loss at −0.8 V vs. SHE, further confirming that the electrocatalytic current originates from hydrogenase and not the nanoITO electrode, consistent with previous O 2 -deactivation experiments. 36 The bioelectrode performance was also investigated under H 2 to understand if nanoITO could influence the reversibility of CpI.…”

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confidence: 99%

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Facile Functionalization of Carbon Electrodes for Efficient Electroenzymatic Hydrogen Production

Liu

Webb

Moreno‐García

et al. 2023

JACS Au

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Enzymatic electrocatalysis holds promise for new biotechnological approaches to produce chemical commodities such as molecular hydrogen (H2). However, typical inhibitory limitations include low stability and/or low electrocatalytic currents (low product yields). Here we report a facile single-step electrode preparation procedure using indium–tin oxide nanoparticles on carbon electrodes. The subsequent immobilization of a model [FeFe]-hydrogenase from Clostridium pasteurianum (“CpI”) on the functionalized carbon electrode permits comparatively large quantities of H2 to be produced in a stable manner. Specifically, we observe current densities of >8 mA/cm2 at −0.8 V vs the standard hydrogen electrode (SHE) by direct electron transfer (DET) from cyclic voltammetry, with an onset potential for H2 production close to its standard potential at pH 7 (approximately −0.4 V vs. SHE). Importantly, hydrogenase-modified electrodes show high stability retaining ∼92% of their electrocatalytic current after 120 h of continuous potentiostatic H2 production at −0.6 V vs. SHE; gas chromatography confirmed ∼100% Faradaic efficiency. As the bioelectrode preparation method balances simplicity, performance, and stability, it paves the way for DET on other electroenzymatic reactions as well as semiartificial photosynthesis.

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confidence: 82%

mentioning

confidence: 99%

Facile Functionalization of Carbon Electrodes for Efficient Electroenzymatic Hydrogen Production

Liu

Webb

Moreno‐García

et al. 2023

JACS Au

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Section: ■ Resultsmentioning

confidence: 99%

“…From the relative distribution of isotopologue products of acetylene, proton, and cyanide reduction assays, the isotope effects of hydrogen/deuterium addition were determined for these processes. Under conditions when a process involves two proton/deuteron transfer steps, each with the same isotope effect, the mole fraction of each of the isotopologue products can be expressed in terms of the isotope effect and the deuterium enrichment of the solvent by the following equations (see Supporting Information for derivation) , X 2 normalH : 0 normalD = I E 2 f normalH 2 false( I E f normalH + f normalD false) 2 X 1 normalH : 1 normalD = 2 I E f normalD f normalH false( I E f normalH + f normalD false) 2 X 0 normalH : 2 normalD = f normalD 2 false( I E f normalH + f normalD false) 2 where X 2H:0D , X 1H:1D , a...…”

Section: Resultsmentioning

confidence: 99%

“…From the relative distribution of isotopologue products of acetylene, proton, and cyanide reduction assays, the isotope effects of hydrogen/deuterium addition were determined for these processes. Under conditions when a process involves two proton/deuteron transfer steps, each with the same isotope effect, the mole fraction of each of the isotopologue products can be expressed in terms of the isotope effect and the deuterium enrichment of the solvent by the following equations (see Supporting Information for derivation) 40 , 41 where X 2H:0D , X 1H:1D , and X 0H:2D are the mole fractions of the isotopologue product with 2 Hs (C 2 H 4 or H 2 ), 1 H and 1D (C 2 H 3 D or HD), or 2Ds (C 2 H 2 D 2 or D 2 ) incorporated, respectively. IE is the isotope effect of H/D addition ( k H / k D ), and f H and f D are the mole fractions of hydrogen and deuterium in the solvent, respectively.…”

Section: Resultsmentioning

confidence: 99%

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Solvent Deuterium Isotope Effects of Substrate Reduction by Nitrogenase from Azotobacter vinelandii

MacArdle

Rees

2022

J. Am. Chem. Soc.

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The mechanism of nitrogenase, the enzyme responsible for biological nitrogen fixation, has been of great interest for understanding the catalytic strategy utilized to reduce dinitrogen to ammonia under ambient temperatures and pressures. The reduction mechanism of nitrogenase is generally envisioned as involving multiple cycles of electron and proton transfers, with the known substrates requiring at least two cycles. Solvent kinetic isotope effect experiments, in which changes of reaction rates or product distribution are measured upon enrichment of solvent with heavy atom isotopes, have been valuable for deciphering the mechanism of complex enzymatic reactions involving proton or hydrogen transfer. We report the distribution of ethylene, dihydrogen, and methane isotopologue products measured from nitrogenase-catalyzed reductions of acetylene, protons, and cyanide, respectively, performed in varying levels of deuterium enrichment of the solvent. As has been noted previously, the total rate of product formation by nitrogenase is largely insensitive to the presence of D 2 O in the solvent. Nevertheless, the incorporation of H/D into products can be measured for these substrates that reflect solvent isotope effects on hydrogen atom transfers that are faster than the overall rate-determining step for nitrogenase. From these data, a minimal isotope effect is observed for acetylene reduction (1.4 ± 0.05), while the isotope effects for hydrogen and methane evolution are significantly higher at 4.2 ± 0.1 and 4.4 ± 0.1, respectively. These results indicate that there are pronounced differences in the sensitivity to isotopic substitution of the hydrogen atom transfer steps associated with the reduction of these substrates by nitrogenase.

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Mesoporöses Indiumzinnoxid Steigert die Elektrokatalytische Leistung und Stabilität von [FeFe]‐Hydrogenasen während der Wasserstoffproduktion

Webb,

Veliju,

Maroni

et al. 2024

Angewandte Chemie

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The metalloenzyme [FeFe]‐hydrogenase is of interest to future biotechnologies targeting the production of “green” hydrogen (H2). We recently developed a simple two‐step functionalized procedure to immobilize the [FeFe]‐hydrogenase from Clostridium pasteurianum (“CpI”) on mesoporous indium tin oxide (ITO) electrodes to achieve elevated H2 production with high operational stability, with current densities of 8 mA cm–2. Here, we use a combination of atomic force microscopy (AFM), scanning electron microscopy (SEM) and electrochemical quartz crystal microbalance (EQCM) to understand how mesoporous ITO stabilizes and activates CpI for electroenzymatic H2 production. Examination of the topography and morphology of the mesoporous ITO surface revealed a hierarchical morphology containing cavities and well‐defined nanoparticle agglomerates. Any potential effect of mesoporosity was investigated by comparing the stability and electroenzymatic activity of CpI on mesoporous ‘nanoITO’ and planar ITO, where we determined that CpI has a higher turnover frequency and absorbs with greater stability (with respect to electroenzymatic activity over time) to nanoITO surfaces.

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Following Electroenzymatic Hydrogen Production by Rotating Ring–Disk Electrochemistry and Mass Spectrometry**

Abstract: File list (3) download file view on ChemRxiv 170121 MS file.pdf (1.13 MiB) download file view on ChemRxiv 170121 Supporting information.pdf (1.82 MiB)

Cited by 8 publications

References 37 publications

Facile Functionalization of Carbon Electrodes for Efficient Electroenzymatic Hydrogen Production

Facile Functionalization of Carbon Electrodes for Efficient Electroenzymatic Hydrogen Production

Solvent Deuterium Isotope Effects of Substrate Reduction by Nitrogenase from Azotobacter vinelandii

Mesoporöses Indiumzinnoxid Steigert die Elektrokatalytische Leistung und Stabilität von [FeFe]‐Hydrogenasen während der Wasserstoffproduktion

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