Water oxidation at low potential exploiting a nitroxide/oxoammonium ion redox couple as mediator

Antonio Barbon; Abdirisak Ahmed Isse; Armando Gennaro; Raanan Carmieli; Itzhak Bilkis; Lev Weiner

doi:10.1039/d2ma00668e

Water oxidation at low potential exploiting a nitroxide/oxoammonium ion redox couple as mediator

Antonio Barbon^*, Abdirisak Ahmed Isse, Armando Gennaro, Raanan Carmieli, Itzhak Bilkis^*, Lev Weiner^*

^*Corresponding author for this work

Institute of Biochemistry, Food Science and Nutrition

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

1 Scopus citations

Abstract

The oxoammonium cation (OAC) of 3-carboxy proxyl, a nitroxide radical (NitR), could be produced either by chemical or by electrochemical oxidation (0.8-1.0 V vs. NHE) of the radical. We have determined that in dilute aqueous basic solutions (pH ≥ 9), OAC is reduced quantitatively to the original radical with concomitant formation of molecular oxygen in a ratio ca. 4 : 1 (4 moles of OAC reduced per 1 mole of O₂), and the redox cycle can be repeated. The low electrolysis potential (0.8 V) contrasts with the high redox potential of the bare OH⁻ anion (2-2.6 V vs. NHE for the first outer-sphere electron transfer). This apparent thermodynamic paradox was solved by a careful study of its possible mechanism. In our opinion, OAC/NitR's may represent a new class of redox mediators for a novel approach to water oxidation (and generation of molecular oxygen) at a low potential.

Original language	English
Pages (from-to)	8149-8156
Number of pages	8
Journal	Materials Advances
Volume	3
Issue number	22
DOIs	https://doi.org/10.1039/d2ma00668e
State	Published - 27 Sep 2022

Bibliographical note

Publisher Copyright:
© 2022 RSC.

Access to Document

10.1039/d2ma00668e

Cite this

@article{99b2026e691e467fa4605e62abd113f1,

title = "Water oxidation at low potential exploiting a nitroxide/oxoammonium ion redox couple as mediator",

abstract = "The oxoammonium cation (OAC) of 3-carboxy proxyl, a nitroxide radical (NitR), could be produced either by chemical or by electrochemical oxidation (0.8-1.0 V vs. NHE) of the radical. We have determined that in dilute aqueous basic solutions (pH ≥ 9), OAC is reduced quantitatively to the original radical with concomitant formation of molecular oxygen in a ratio ca. 4 : 1 (4 moles of OAC reduced per 1 mole of O2), and the redox cycle can be repeated. The low electrolysis potential (0.8 V) contrasts with the high redox potential of the bare OH− anion (2-2.6 V vs. NHE for the first outer-sphere electron transfer). This apparent thermodynamic paradox was solved by a careful study of its possible mechanism. In our opinion, OAC/NitR's may represent a new class of redox mediators for a novel approach to water oxidation (and generation of molecular oxygen) at a low potential.",

author = "Antonio Barbon and Isse, {Abdirisak Ahmed} and Armando Gennaro and Raanan Carmieli and Itzhak Bilkis and Lev Weiner",

note = "Publisher Copyright: {\textcopyright} 2022 RSC.",

year = "2022",

month = sep,

day = "27",

doi = "10.1039/d2ma00668e",

language = "אנגלית",

volume = "3",

pages = "8149--8156",

journal = "Materials Advances",

issn = "2633-5409",

publisher = "Royal Society of Chemistry",

number = "22",

}

TY - JOUR

T1 - Water oxidation at low potential exploiting a nitroxide/oxoammonium ion redox couple as mediator

AU - Barbon, Antonio

AU - Isse, Abdirisak Ahmed

AU - Gennaro, Armando

AU - Carmieli, Raanan

AU - Bilkis, Itzhak

AU - Weiner, Lev

PY - 2022/9/27

Y1 - 2022/9/27

N2 - The oxoammonium cation (OAC) of 3-carboxy proxyl, a nitroxide radical (NitR), could be produced either by chemical or by electrochemical oxidation (0.8-1.0 V vs. NHE) of the radical. We have determined that in dilute aqueous basic solutions (pH ≥ 9), OAC is reduced quantitatively to the original radical with concomitant formation of molecular oxygen in a ratio ca. 4 : 1 (4 moles of OAC reduced per 1 mole of O2), and the redox cycle can be repeated. The low electrolysis potential (0.8 V) contrasts with the high redox potential of the bare OH− anion (2-2.6 V vs. NHE for the first outer-sphere electron transfer). This apparent thermodynamic paradox was solved by a careful study of its possible mechanism. In our opinion, OAC/NitR's may represent a new class of redox mediators for a novel approach to water oxidation (and generation of molecular oxygen) at a low potential.

AB - The oxoammonium cation (OAC) of 3-carboxy proxyl, a nitroxide radical (NitR), could be produced either by chemical or by electrochemical oxidation (0.8-1.0 V vs. NHE) of the radical. We have determined that in dilute aqueous basic solutions (pH ≥ 9), OAC is reduced quantitatively to the original radical with concomitant formation of molecular oxygen in a ratio ca. 4 : 1 (4 moles of OAC reduced per 1 mole of O2), and the redox cycle can be repeated. The low electrolysis potential (0.8 V) contrasts with the high redox potential of the bare OH− anion (2-2.6 V vs. NHE for the first outer-sphere electron transfer). This apparent thermodynamic paradox was solved by a careful study of its possible mechanism. In our opinion, OAC/NitR's may represent a new class of redox mediators for a novel approach to water oxidation (and generation of molecular oxygen) at a low potential.

UR - http://www.scopus.com/inward/record.url?scp=85140440240&partnerID=8YFLogxK

U2 - 10.1039/d2ma00668e

DO - 10.1039/d2ma00668e

M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???

AN - SCOPUS:85140440240

SN - 2633-5409

VL - 3

SP - 8149

EP - 8156

JO - Materials Advances

JF - Materials Advances

IS - 22

ER -

Water oxidation at low potential exploiting a nitroxide/oxoammonium ion redox couple as mediator

Abstract

Bibliographical note

Access to Document

Other files and links

Fingerprint

Cite this