Trapping an Iron(VI) Water-Splitting Intermediate in Nonaqueous Media

Hunter, Bryan M.; Thompson, Niklas B.; Müller, Astrid M.; Rossman, George R.; Hill, Michael G.; Winkler, Jay R.

doi:10.1016/j.joule.2018.01.008

Cited by 181 publications

(193 citation statements)

References 40 publications

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“…Calvillo et al has reported surface Fe oxidation on Co x Fe 3Àx O 4 spinels at OER potentials after extended cycling. [10,11,13] [32] Thed ata reported herein are consistent with oxidized Fe species playing ak ey role in the OER mechanism on Co(Fe)O x H y .The energy of the X-ray absorption edge reports on the average oxidation state of all the metal cations.Inthe case of Fe-free CoO x H y ,Co 3+ is,onaverage,further oxidized during OER.…”

supporting

confidence: 81%

“…[11] Balasubramanian et al [32] reported similar Fe oxidation in anodically polarized NiOOH measured ex situ. [11] Balasubramanian et al [32] reported similar Fe oxidation in anodically polarized NiOOH measured ex situ.…”

mentioning

confidence: 78%

“…[3][4][5][6][7][8][9] Friebel et al [3] determined that in Ni(Fe)O x H y the Fe À Ob ond length during the OER was similar to that of NiOOH, which is shorter than in FeOOH. [11] DFT calculations have also pointed to the presence of higher Fe oxidation states (> 3 +)i nN i(Fe)O x H y during the OER that facilitate catalysis. [10] Hunter et al reported evidence of Fe 6+ under anodic bias in non-aqueous electrolytes.…”

mentioning

confidence: 99%

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Operando X‐Ray Absorption Spectroscopy Shows Iron Oxidation Is Concurrent with Oxygen Evolution in Cobalt–Iron (Oxy)hydroxide Electrocatalysts

et al. 2018

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Iron cations are essential for the high activity of nickel and cobalt-based (oxy)hydroxides for the oxygen evolution reaction, but the role of iron in the catalytic mechanism remains under active investigation. Operando X-ray absorption spectroscopy and density functional theory calculations are used to demonstrate partial Fe oxidation and a shortening of the Fe-O bond length during oxygen evolution on Co(Fe)O H . Cobalt oxidation during oxygen evolution is only observed in the absence of iron. These results demonstrate a different mechanism for water oxidation in the presence and absence of iron and support the hypothesis that oxidized iron species are involved in water-oxidation catalysis on Co(Fe)O H .

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supporting

confidence: 81%

mentioning

confidence: 78%

mentioning

confidence: 99%

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Operando X‐Ray Absorption Spectroscopy Shows Iron Oxidation Is Concurrent with Oxygen Evolution in Cobalt–Iron (Oxy)hydroxide Electrocatalysts

et al. 2018

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“…It is well known that the effective adsorption of OH À and H 2 Oo n ac atalyst plays an important role in the OER. [31] To further elucidate the origins of the high OER activity of Ni-Fe-MOF NSs,DFT + Ucomputations were performed to calculate the Gibbs free energy of elementary steps and overpotential for OER. TheO ER activity of Ni-MOF NSs (386 mV at 10 mA cm À2 ) was almost identical to that reported for Co-MOFs (387 mV at 10 mA cm À2 ).…”

Section: Angewandte Chemiementioning

confidence: 99%

Large‐Scale, Bottom‐Up Synthesis of Binary Metal–Organic Framework Nanosheets for Efficient Water Oxidation

et al. 2019

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Ultrathin metal-organic framework (MOF) nanosheets (NSs) offer potential for many applications,b ut the synthetic strategies are largely limited to top-down, low-yield exfoliation methods.H erein, Ni-M-MOF (M = Fe,A l, Co, Mn, Zn, and Cd) NSs are reported with at hickness of only several atomic layers,p repared by al arge-scale,b ottom-up solvothermal method. The solvent mixture of N,N-dimethylacetamide and water playskey role in controlling the formation of these two-dimensional MOF NSs.T he MOF NSs can be directly used as efficient electrocatalysts for the oxygen evolution reaction, in which the Ni-Fe-MOF NSs deliver ac urrent density of 10 mA cm À2 at al ow overpotential of 221 mV with asmall Tafel slope of 56.0 mV dec À1 ,and exhibit excellent stability for at least 20 hw ithout obvious activity decay. Density functional theory calculations on the energy barriers for OER occurring at different metal sites confirm that Fe is the active site for OER at Ni-Fe-MOF NSs.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

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“…An intensively investigated example is the inclusion of Fe into other TM systems such as Ni and Co. [27][28][29][30][31][32][33][34][35][36] In these materials, the included Fe cations drastically increase the OER activity, where Fe is proposed to act as the catalytically most active site. [27,[30][31][32][33][37][38] However, poor catalytic activities are observed for heterometal-free FeO x H y , [37,39,40] due to its low electric conductivity. [29,37,41] Similarly, homometallic iron sulfides usually show low catalytic activities for the OER.…”

Section: Introductionmentioning

confidence: 99%

Stannites – A New Promising Class of Durable Electrocatalysts for Efficient Water Oxidation

et al. 2020

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The oxygen evolution reaction (OER) through water oxidation is a key process for multiple energy storage technologies required for a sustainable energy economy such as the formation of the fuel hydrogen from water and electricity, or metal‐air batteries. Herein, we investigate the suitability of Cu2FeSnS4 for the OER and demonstrate its superiority over iron sulfide, iron (oxy)hydroxides and benchmark noble‐metal catalysts in alkaline media. Electrodeposited Cu2FeSnS4 yields the current densities of 10 and 1000 mA/cm2 at overpotentials of merely 228 and 330 mV, respectively. State‐of‐the‐art analytical methods are applied before and after electrocatalysis to uncover the fate of the Cu2FeSnS4 precatalyst under OER conditions and to deduce structure‐activity relationships. Cu2FeSnS4 is the first compound reported for OER among the broad class of stannite structure type materials containing multiple members with highly active earth‐abundant transition‐metals for OER.

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Trapping an Iron(VI) Water-Splitting Intermediate in Nonaqueous Media

Cited by 181 publications

References 40 publications

Operando X‐Ray Absorption Spectroscopy Shows Iron Oxidation Is Concurrent with Oxygen Evolution in Cobalt–Iron (Oxy)hydroxide Electrocatalysts

Operando X‐Ray Absorption Spectroscopy Shows Iron Oxidation Is Concurrent with Oxygen Evolution in Cobalt–Iron (Oxy)hydroxide Electrocatalysts

Large‐Scale, Bottom‐Up Synthesis of Binary Metal–Organic Framework Nanosheets for Efficient Water Oxidation

Stannites – A New Promising Class of Durable Electrocatalysts for Efficient Water Oxidation

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