Mechanism of Water Oxidation by Ferrate(VI) at pH 7–9

Gui Chen; William W.Y. Lam; Po Kam Lo; Wai Lun MAN; Lingjing Chen; Kai Chung Lau; Tai Chu Lau

doi:10.1002/chem.201803757

Mechanism of Water Oxidation by Ferrate(VI) at pH 7–9

Gui Chen, William W.Y. Lam, Po Kam Lo, Wai Lun MAN, Lingjing Chen, Kai Chung Lau^*, Tai Chu Lau

^*Corresponding author for this work

Department of Chemistry

Research output: Contribution to journal › Journal article › peer-review

25 Citations (Scopus)

Abstract

The kinetics of water oxidation by K₂FeO₄ has been reinvestigated by UV/Vis spectrophotometry from pH 7–9 in 0.2 m phosphate buffer. The rate of reaction was found to be second-order in both [FeO₄ ²⁻] and [H⁺]. These results are consistent with a proposed mechanism in which the first step involves the initial equilibrium protonation of FeO₄ ²⁻ to give FeO₃(OH)⁻, which then undergoes rate-limiting O−O bond formation. Analysis of the O₂ isotopic composition for the reaction in H₂ ¹⁸O suggests that the predominant pathway for water oxidation by ferrate is intramolecular O−O coupling. DFT calculations have also been performed, which support the proposed mechanism.

Original language	English
Pages (from-to)	18735-18742
Number of pages	8
Journal	Chemistry - A European Journal
Volume	24
Issue number	70
DOIs	https://doi.org/10.1002/chem.201803757
Publication status	Published - 12 Dec 2018

Scopus Subject Areas

Catalysis
Organic Chemistry

User-Defined Keywords

DFT calculations
diferrate
ferrate
O−O coupling
water oxidation

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10.1002/chem.201803757

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title = "Mechanism of Water Oxidation by Ferrate(VI) at pH 7–9",

abstract = "The kinetics of water oxidation by K2FeO4 has been reinvestigated by UV/Vis spectrophotometry from pH 7–9 in 0.2 m phosphate buffer. The rate of reaction was found to be second-order in both [FeO4 2−] and [H+]. These results are consistent with a proposed mechanism in which the first step involves the initial equilibrium protonation of FeO4 2− to give FeO3(OH)−, which then undergoes rate-limiting O−O bond formation. Analysis of the O2 isotopic composition for the reaction in H2 18O suggests that the predominant pathway for water oxidation by ferrate is intramolecular O−O coupling. DFT calculations have also been performed, which support the proposed mechanism.",

keywords = "DFT calculations, diferrate, ferrate, O−O coupling, water oxidation",

author = "Gui Chen and Lam, {William W.Y.} and Lo, {Po Kam} and MAN, {Wai Lun} and Lingjing Chen and Lau, {Kai Chung} and Lau, {Tai Chu}",

note = "Funding Information: The work described in this paper was supported by the Hong Kong University Grants Committee Area of Excellence Scheme (AoE/P-03-08) and the Research Grants Council of Hong Kong (CityU 11301514, CityU 11301514). G.C. thanks the startup grants from Dongguan University of Technology for high-level talent (G200906-47, GC200109-17 and KCYKYQD2017015).",

year = "2018",

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doi = "10.1002/chem.201803757",

language = "English",

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AU - Chen, Gui

AU - Lam, William W.Y.

AU - Lo, Po Kam

AU - MAN, Wai Lun

AU - Chen, Lingjing

AU - Lau, Kai Chung

AU - Lau, Tai Chu

N1 - Funding Information: The work described in this paper was supported by the Hong Kong University Grants Committee Area of Excellence Scheme (AoE/P-03-08) and the Research Grants Council of Hong Kong (CityU 11301514, CityU 11301514). G.C. thanks the startup grants from Dongguan University of Technology for high-level talent (G200906-47, GC200109-17 and KCYKYQD2017015).

PY - 2018/12/12

Y1 - 2018/12/12

N2 - The kinetics of water oxidation by K2FeO4 has been reinvestigated by UV/Vis spectrophotometry from pH 7–9 in 0.2 m phosphate buffer. The rate of reaction was found to be second-order in both [FeO4 2−] and [H+]. These results are consistent with a proposed mechanism in which the first step involves the initial equilibrium protonation of FeO4 2− to give FeO3(OH)−, which then undergoes rate-limiting O−O bond formation. Analysis of the O2 isotopic composition for the reaction in H2 18O suggests that the predominant pathway for water oxidation by ferrate is intramolecular O−O coupling. DFT calculations have also been performed, which support the proposed mechanism.

AB - The kinetics of water oxidation by K2FeO4 has been reinvestigated by UV/Vis spectrophotometry from pH 7–9 in 0.2 m phosphate buffer. The rate of reaction was found to be second-order in both [FeO4 2−] and [H+]. These results are consistent with a proposed mechanism in which the first step involves the initial equilibrium protonation of FeO4 2− to give FeO3(OH)−, which then undergoes rate-limiting O−O bond formation. Analysis of the O2 isotopic composition for the reaction in H2 18O suggests that the predominant pathway for water oxidation by ferrate is intramolecular O−O coupling. DFT calculations have also been performed, which support the proposed mechanism.

KW - DFT calculations

KW - diferrate

KW - ferrate

KW - O−O coupling

KW - water oxidation

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JO - Chemistry - A European Journal

JF - Chemistry - A European Journal

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Mechanism of Water Oxidation by Ferrate(VI) at pH 7–9

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