Proton switch for modulating oxygen reduction by a copper electrocatalyst embedded in a hybrid bilayer membrane

Barile, Christopher J.; Tse, Edmund C. M.; Liu, Ying; Sobyra, Thomas B.; Zimmerman, Steven C.; Hosseini, Ali; Gewirth, Andrew A.

doi:10.1038/nmat3974

Cited by 52 publications

(74 citation statements)

References 43 publications

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“…2,3 This motivates research in heterogeneous and homogeneous catalysts, from new platinum alloy nanocrystals supported on electrodes 4 to novel earth-abundant carbonaceous materials 5 to unique molecular structures and hybrid combinations. 6,7 Homogeneous electrocatalysts have yet to match heterogeneous materials in turnover frequencies (TOFs) per active site at modest overpotentials, but they permit facile development of important structure/activity and driving force/activation barrier relationships. Such atomic-level understanding is key to building better ORR electrocatalysts.…”

Section: Introductionmentioning

confidence: 99%

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Homogenous Electrocatalytic Oxygen Reduction Rates Correlate with Reaction Overpotential in Acidic Organic Solutions

et al. 2016

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Improved electrocatalysts for the oxygen reduction reaction (ORR) are critical for the advancement of fuel cell technologies. Herein, we report a series of 11 soluble iron porphyrin ORR electrocatalysts that possess turnover frequencies (TOFs) from 3 s–1 to an unprecedented value of 2.2 × 106 s–1. These TOFs correlate with the ORR overpotential, which can be modulated by changing the E1/2 of the catalyst using different ancillary ligands, by changing the solvent and solution acidity, and by changing the catalyst’s protonation state. The overpotential is well-defined for these homogeneous electrocatalysts by the E1/2 of the catalyst and the proton activity of the solution. This is the first such correlation for homogeneous ORR electrocatalysis, and it demonstrates that the remarkably fast TOFs are a consequence of high overpotential. The correlation with overpotential is surprising since the turnover limiting steps involve oxygen binding and protonation, as opposed to turnover limiting electron transfer commonly found in Tafel analysis of heterogeneous ORR materials. Computational studies show that the free energies for oxygen binding to the catalyst and for protonation of the superoxide complex are in general linearly related to the catalyst E1/2, and that this is the origin of the overpotential correlations. This analysis thus provides detailed understanding of the ORR barriers. The best catalysts involve partial decoupling of the influence of the second coordination sphere from the properties of the metal center, which is suggested as new molecular design strategy to avoid the limitations of the traditional scaling relationships for these catalysts.

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Section: Introductionmentioning

confidence: 99%

“…In these situations, differing local environments complicate understanding, 13 with some elegant exceptions. 7,14 …”

Section: Introductionmentioning

confidence: 99%

Homogenous Electrocatalytic Oxygen Reduction Rates Correlate with Reaction Overpotential in Acidic Organic Solutions

et al. 2016

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“…[1][2][3][4][5][6][7][8][9] Using renewable sources of energy to power water-splitting electrolyzers offers a promising system to generate H 2 with almost no carbon footprint. [10][11][12] An electrolyzer is an energy conversion device that splits water into H 2 and O 2 via the following two half-cell reactions: the cathodic hydrogen evolution reaction (HER, 2H + + 2e -→ H 2 ) and the anodic oxygen evolution reaction (OER, 4OH -→ 2H 2 O + 4e -+ O 2 ), 13 also known as the water oxidation reaction.…”

Section: Introductionmentioning

confidence: 99%

Observation of an Inverse Kinetic Isotope Effect in Oxygen Evolution Electrochemistry

et al. 2016

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Earth-abundant and inexpensive catalysts with low overpotential and high durability are central to the development of efficient water splitting electrolyzers. However, improvements in catalyst design and preparation are currently hampered by the lack of detailed understanding of the reaction mechanisms of the oxygen evolution reaction (OER) facilitated by non-precious metal (NPM) catalysts. In this manuscript, we conducted a kinetic isotope effect (KIE) study in an effort to identify the rate-determining step (RDS) of these intricate electrocatalytic reactions involving multiple proton-coupled electron transfer (PCET) processes. We observed an inverse KIE for OER catalyzed by Ni and Co electrodes. These results contribute to a more complete understanding of the OER mechanism and allow for the future development of improved NPM catalysts.

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“…Indeed catalyzed ORR is achieved with high efficiency and selectivity both in nature by cytochrome c oxidases and related oxidases and in many fuel cells by precious Pt‐based catalysts . Recently, substantial progress has been achieved in the electrochemical ORR with various non‐precious Fe, Co, Mn, Cu, and Ni catalysts.

true O_{2} + 4 {normalH}^{+} + 4 {normale}^{-} \vec{\leftarrow} 2 H_{2} normalO E^{0} = 1.23 normalV

…”

Section: Figurementioning

confidence: 99%

Efficient Solar‐Assisted O₂ Reduction Using a Cofacial Iron Porphyrin Dimer Catalyst Integrated into a p‐CuBi₂O₄ Photocathode

Zahran

Mohamed

Haleem

et al. 2018

Chemistry A European J

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A cofacial iron porphyrin heterodimer, Fe TPFPP-TMP showed high electrocatalytic activity, selectivity, and stability for O reduction to H O both in homogeneous non-aqueous and heterogeneous neutral aqueous solutions. When it is integrated to FTO/p-CuBi O (FTO=fluorine doped tin oxide) photocathode prepared by a simple novel method, a remarkable efficient solar-assisted O reduction is achieved in neutral potassium phosphate (KPi) or basic NaOH solutions saturated with O .

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Proton switch for modulating oxygen reduction by a copper electrocatalyst embedded in a hybrid bilayer membrane

Cited by 52 publications

References 43 publications

Homogenous Electrocatalytic Oxygen Reduction Rates Correlate with Reaction Overpotential in Acidic Organic Solutions

Homogenous Electrocatalytic Oxygen Reduction Rates Correlate with Reaction Overpotential in Acidic Organic Solutions

Observation of an Inverse Kinetic Isotope Effect in Oxygen Evolution Electrochemistry

Efficient Solar‐Assisted O₂ Reduction Using a Cofacial Iron Porphyrin Dimer Catalyst Integrated into a p‐CuBi₂O₄ Photocathode

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Proton switch for modulating oxygen reduction by a copper electrocatalyst embedded in a hybrid bilayer membrane

Cited by 52 publications

References 43 publications

Homogenous Electrocatalytic Oxygen Reduction Rates Correlate with Reaction Overpotential in Acidic Organic Solutions

Homogenous Electrocatalytic Oxygen Reduction Rates Correlate with Reaction Overpotential in Acidic Organic Solutions

Observation of an Inverse Kinetic Isotope Effect in Oxygen Evolution Electrochemistry

Efficient Solar‐Assisted O2 Reduction Using a Cofacial Iron Porphyrin Dimer Catalyst Integrated into a p‐CuBi2O4 Photocathode

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Efficient Solar‐Assisted O₂ Reduction Using a Cofacial Iron Porphyrin Dimer Catalyst Integrated into a p‐CuBi₂O₄ Photocathode