Cobalt Carbonate as an Electrocatalyst for Water Oxidation

Shanti G. Patra; Erzsébet Illés; Amir Mizrahi; Dan Meyerstein

doi:10.1002/chem.201904051

Cobalt Carbonate as an Electrocatalyst for Water Oxidation

Shanti G. Patra, Erzsébet Illés, Amir Mizrahi, Dan Meyerstein

Department of Chemical Sciences

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

Co^II salts in the presence of HCO₃ ⁻/CO₃ ²⁻ in aqueous solutions act as electrocatalysts for water oxidation. It comprises of several key steps: (i) A relatively small wave at E_pa≈0.71 V (vs. Ag/AgCl) owing to the Co^III/II redox couple. (ii) A second wave is observed at E_pa≈1.10 V with a considerably larger current. In which the Co^III undergoes oxidation to form a Co^IV species. The large current is attributed to catalytic oxidation of HCO₃ ⁻/CO₃ ²⁻ to HCO₄ ⁻. (iii) A process with very large currents at >1.2 V owing to the formation of Co^V(CO₃)₃ ⁻, which oxidizes both water and HCO₃ ⁻/CO₃ ²⁻. These processes depend on [Co^II], [NaHCO₃], and pH. Chronoamperometry at 1.3 V gives a green deposit. It acts as a heterogeneous catalyst for water oxidation. DFT calculations point out that Coⁿ(CO₃)₃ ⁿ⁻⁶, n=4, 5 are attainable at potentials similar to those experimentally observed.

Original language	English
Pages (from-to)	711-720
Number of pages	10
Journal	Chemistry - A European Journal
Volume	26
Issue number	3
DOIs	https://doi.org/10.1002/chem.201904051
State	Published - 13 Jan 2020

Keywords

cobalt carbonate
density functional calculations
electrochemistry
peroxo-monocarbonate
water oxidation

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title = "Cobalt Carbonate as an Electrocatalyst for Water Oxidation",

abstract = "CoII salts in the presence of HCO3 −/CO3 2− in aqueous solutions act as electrocatalysts for water oxidation. It comprises of several key steps: (i) A relatively small wave at Epa≈0.71 V (vs. Ag/AgCl) owing to the CoIII/II redox couple. (ii) A second wave is observed at Epa≈1.10 V with a considerably larger current. In which the CoIII undergoes oxidation to form a CoIV species. The large current is attributed to catalytic oxidation of HCO3 −/CO3 2− to HCO4 −. (iii) A process with very large currents at >1.2 V owing to the formation of CoV(CO3)3 −, which oxidizes both water and HCO3 −/CO3 2−. These processes depend on [CoII], [NaHCO3], and pH. Chronoamperometry at 1.3 V gives a green deposit. It acts as a heterogeneous catalyst for water oxidation. DFT calculations point out that Con(CO3)3 n−6, n=4, 5 are attainable at potentials similar to those experimentally observed.",

keywords = "cobalt carbonate, density functional calculations, electrochemistry, peroxo-monocarbonate, water oxidation",

author = "Patra, {Shanti G.} and Erzs{\'e}bet Ill{\'e}s and Amir Mizrahi and Dan Meyerstein",

note = "Publisher Copyright: {\textcopyright} 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim",

year = "2020",

month = jan,

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doi = "10.1002/chem.201904051",

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AU - Patra, Shanti G.

AU - Illés, Erzsébet

AU - Mizrahi, Amir

AU - Meyerstein, Dan

PY - 2020/1/13

Y1 - 2020/1/13

N2 - CoII salts in the presence of HCO3 −/CO3 2− in aqueous solutions act as electrocatalysts for water oxidation. It comprises of several key steps: (i) A relatively small wave at Epa≈0.71 V (vs. Ag/AgCl) owing to the CoIII/II redox couple. (ii) A second wave is observed at Epa≈1.10 V with a considerably larger current. In which the CoIII undergoes oxidation to form a CoIV species. The large current is attributed to catalytic oxidation of HCO3 −/CO3 2− to HCO4 −. (iii) A process with very large currents at >1.2 V owing to the formation of CoV(CO3)3 −, which oxidizes both water and HCO3 −/CO3 2−. These processes depend on [CoII], [NaHCO3], and pH. Chronoamperometry at 1.3 V gives a green deposit. It acts as a heterogeneous catalyst for water oxidation. DFT calculations point out that Con(CO3)3 n−6, n=4, 5 are attainable at potentials similar to those experimentally observed.

AB - CoII salts in the presence of HCO3 −/CO3 2− in aqueous solutions act as electrocatalysts for water oxidation. It comprises of several key steps: (i) A relatively small wave at Epa≈0.71 V (vs. Ag/AgCl) owing to the CoIII/II redox couple. (ii) A second wave is observed at Epa≈1.10 V with a considerably larger current. In which the CoIII undergoes oxidation to form a CoIV species. The large current is attributed to catalytic oxidation of HCO3 −/CO3 2− to HCO4 −. (iii) A process with very large currents at >1.2 V owing to the formation of CoV(CO3)3 −, which oxidizes both water and HCO3 −/CO3 2−. These processes depend on [CoII], [NaHCO3], and pH. Chronoamperometry at 1.3 V gives a green deposit. It acts as a heterogeneous catalyst for water oxidation. DFT calculations point out that Con(CO3)3 n−6, n=4, 5 are attainable at potentials similar to those experimentally observed.

KW - cobalt carbonate

KW - density functional calculations

KW - electrochemistry

KW - peroxo-monocarbonate

KW - water oxidation

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Cobalt Carbonate as an Electrocatalyst for Water Oxidation

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