XAFS of short-lived reduction products of structural and functional models of the [Fe–Fe] hydrogenase H-cluster

Bondin, Mark I.; Borg, Stacey J.; Cheah, Mun-Hon; Best, Stephen P.

doi:10.1016/j.radphyschem.2005.07.043

Cited by 6 publications

(2 citation statements)

References 18 publications

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“…[32,33] To further determine the local electronic structure of Fe sites at the atomic level, we conducted extended X-ray absorption fine structure (EXAFS) spectroscopy characterizations, and the results of the k 3 -weighted EXAFS spectra are presented in Figure 2e. Combining the results of N 1s XPS and N K-edge XANES of Fe-HDNSs, the dominant peak at ≈1.5 Å of the Fe-HDNSs catalysts can be attributed to the first-shell of Fe-N/O coordination, [34][35][36] while the contrast Fe NPs samples exhibit an Fe-Fe scattering peak consistent with Fe foil at ≈2.1 Å. Remarkably, Figure 2f clearly shows that the Fe-HDNSs catalysts possess a characteristic peak at ≈2.6 Å, which originates from the presence of metal coordination between the high-density Fe sites with distances <3 Å.…”

Section: Electronic Structure Characterization Of Electrocatalystsmentioning

confidence: 89%

In situ Activation of Molecular Oxygen at Intermetallic Spacing‐Optimized Iron Network‐Like Sites for Boosting Electrocatalytic Oxygen Reduction

Jiang,

Zhou,

Jiang

et al. 2024

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The oxygen reduction reaction (ORR) catalyzed by transition‐metal single‐atom catalysts (SACs) is promising for practical applications in energy‐conversion devices, but great challenges still remain due to the sluggish kinetics of O═O cleavage. Herein, a kind of high‐density iron network‐like sites catalysts are constructed with optimized intermetallic distances on an amino‐functionalized carbon matrix (Fe‐HDNSs). Quasi‐in situ soft X‐ray absorption spectroscopy and in situ synchrotron infrared characterizations demonstrate that the optimized intermetallic distances in Fe‐HDNSs can in situ activate the molecular oxygen by fast electron compensation through the hybridized Fe 3d‒O 2p, which efficiently facilitates the cleavage of the O═O bond to *O species and highly suppresses the side reactions for an accelerated kinetics of the 4e− ORR. As a result, the well‐designed Fe‐HDNSs catalysts exhibit superior performances with a half‐wave potential of 0.89 V versus reversible hydrogen electrode (RHE) and a kinetic current density of 72 mA cm−2@0.80 V versus RHE, exceeding most of the noble‐metal‐free ORR catalysts. This work offers some new insights into the understanding of 4e− ORR kinetics and reaction pathways to boost electrochemical performances of SACs.

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Section: Electronic Structure Characterization Of Electrocatalystsmentioning

confidence: 89%

In situ Activation of Molecular Oxygen at Intermetallic Spacing‐Optimized Iron Network‐Like Sites for Boosting Electrocatalytic Oxygen Reduction

Jiang,

Zhou,

Jiang

et al. 2024

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“…The first, adopted by Best et al, is to freeze the electrolyte, trap unstable product species, and collect data at low temperatures to reduce beam damage. − This is successful for moderately stable products but faces limitations for reactive species as it is dependent on the rate at which these species generated by electrolysis can be removed and quenched. The second alternative strategy is to use a channel-flow electrochemical cell.…”

Section: Introductionmentioning

confidence: 99%

Channel-Flow Cell for X-ray Absorption Spectroelectrochemistry

et al. 2008

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X-ray absorption spectroscopy has the potential to provide valuable information not obtainable by other spectroscopic techniques on the structure of intermediates in electron-transfer reactions. Microfocused X-rays have been identified as powerful tools for probing the solution in the vicinity of the working electrode, and the design of an electrochemical flow cell suitable for such measurements is described. The flowing solution, found to be essential to remove any products of beam damage, is characterized by mapping X-ray absorption changes as a function of applied potential and position within the channel. [{Fe(η5-C5H5)(CO)(μ-SPh)}2], used as a model system, undergoes two reversible, one-electron oxidations giving rise to a shortening of the Fe−Fe distance and significant changes in X-ray absorption, making it an ideal compound for trial studies. Two-dimensional numerical modeling is used to rationalize the observed absorption changes and hence solution composition. Excellent agreement between calculated and observed changes in absorbance is found in the vicinity of the electrode although there are substantial differences where forced convection dominates mass transport. These experiments represent the first steps in demonstrating that the combination of microfocused X-rays with electrochemical flow cells has the potential to be a powerful technique for opening up new possibilities for studies of intermediates in electron-transfer reactions.

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An unexpected leading role for [Fe2(CO)6(μ-pdt)] in our understanding of [FeFe]-H2ases and the search for clean hydrogen production

Hogarth

2023

Coordination Chemistry Reviews

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XAFS of short-lived reduction products of structural and functional models of the [Fe–Fe] hydrogenase H-cluster

Cited by 6 publications

References 18 publications

In situ Activation of Molecular Oxygen at Intermetallic Spacing‐Optimized Iron Network‐Like Sites for Boosting Electrocatalytic Oxygen Reduction

In situ Activation of Molecular Oxygen at Intermetallic Spacing‐Optimized Iron Network‐Like Sites for Boosting Electrocatalytic Oxygen Reduction

Channel-Flow Cell for X-ray Absorption Spectroelectrochemistry

An unexpected leading role for [Fe2(CO)6(μ-pdt)] in our understanding of [FeFe]-H2ases and the search for clean hydrogen production

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