The thermoelectrochemistry of the aqueous iron(ii)/iron(iii) redox couple

Significance of the anion and pH in thermogalvanic thermal-to-electrical energy conversion

Mark A. Buckingham, Frank Marken, Leigh Aldous

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Thermogalvanic conversion of temperature gradients into electricity via a redox couple represents a potential method of waste energy harvesting, but inexpensive, effective and sustainable redox couples are required. In this study four aqueous Fe(ii)/Fe(iii) salt systems are considered, based upon ammonium iron sulphate, iron sulphate, iron trifluoromethanesulfonate and iron nitrate. A range of Seebeck coefficients were observed, from +0.18 ± 0.04 mV K-1 for ammonium iron(ii/iii) sulphate to +1.46 ± 0.02 mV K-1 for acidified iron(ii/iii) trifluoromethanesulfonate, both at a temperature difference of 20 K; notably these apparent Seebeck coefficients vary with temperature difference due to significant chemical equilibria. The iron(ii/iii) nitrate system generated the highest thermogalvanic power output. The systems were probed by cyclic voltammetry, pH, UV-Vis spectroscopy and electrochemical impedance spectroscopy, and two competing mechanisms noted, which strongly affect both the current output and Seebeck coefficient (i.e. potential output) of their thermoelectrochemical cells (or thermocells). Green and economic consideration are important aspects if these systems are to be employed in harvesting low-grade heat energy at a larger scale; iron nitrate and acidified iron sulphate were the most highly competitive systems.

Original languageEnglish
Pages (from-to)2717-2726
Number of pages10
JournalSustainable Energy and Fuels
Volume2
Issue number12
DOIs
Publication statusPublished - 1 Dec 2018

ASJC Scopus subject areas

  • Energy Engineering and Power Technology
  • Fuel Technology
  • Renewable Energy, Sustainability and the Environment

Cite this

@article{94374086068748b0bf3f7fc2ef32b30a,
title = "The thermoelectrochemistry of the aqueous iron(ii)/iron(iii) redox couple: Significance of the anion and pH in thermogalvanic thermal-to-electrical energy conversion",
abstract = "Thermogalvanic conversion of temperature gradients into electricity via a redox couple represents a potential method of waste energy harvesting, but inexpensive, effective and sustainable redox couples are required. In this study four aqueous Fe(ii)/Fe(iii) salt systems are considered, based upon ammonium iron sulphate, iron sulphate, iron trifluoromethanesulfonate and iron nitrate. A range of Seebeck coefficients were observed, from +0.18 ± 0.04 mV K-1 for ammonium iron(ii/iii) sulphate to +1.46 ± 0.02 mV K-1 for acidified iron(ii/iii) trifluoromethanesulfonate, both at a temperature difference of 20 K; notably these apparent Seebeck coefficients vary with temperature difference due to significant chemical equilibria. The iron(ii/iii) nitrate system generated the highest thermogalvanic power output. The systems were probed by cyclic voltammetry, pH, UV-Vis spectroscopy and electrochemical impedance spectroscopy, and two competing mechanisms noted, which strongly affect both the current output and Seebeck coefficient (i.e. potential output) of their thermoelectrochemical cells (or thermocells). Green and economic consideration are important aspects if these systems are to be employed in harvesting low-grade heat energy at a larger scale; iron nitrate and acidified iron sulphate were the most highly competitive systems.",
author = "Buckingham, {Mark A.} and Frank Marken and Leigh Aldous",
year = "2018",
month = "12",
day = "1",
doi = "10.1039/c8se00416a",
language = "English",
volume = "2",
pages = "2717--2726",
journal = "Sustainable Energy & Fuels",
issn = "2398-4902",
publisher = "Royal Society of Chemistry",
number = "12",

}

TY - JOUR

T1 - The thermoelectrochemistry of the aqueous iron(ii)/iron(iii) redox couple

T2 - Significance of the anion and pH in thermogalvanic thermal-to-electrical energy conversion

AU - Buckingham, Mark A.

AU - Marken, Frank

AU - Aldous, Leigh

PY - 2018/12/1

Y1 - 2018/12/1

N2 - Thermogalvanic conversion of temperature gradients into electricity via a redox couple represents a potential method of waste energy harvesting, but inexpensive, effective and sustainable redox couples are required. In this study four aqueous Fe(ii)/Fe(iii) salt systems are considered, based upon ammonium iron sulphate, iron sulphate, iron trifluoromethanesulfonate and iron nitrate. A range of Seebeck coefficients were observed, from +0.18 ± 0.04 mV K-1 for ammonium iron(ii/iii) sulphate to +1.46 ± 0.02 mV K-1 for acidified iron(ii/iii) trifluoromethanesulfonate, both at a temperature difference of 20 K; notably these apparent Seebeck coefficients vary with temperature difference due to significant chemical equilibria. The iron(ii/iii) nitrate system generated the highest thermogalvanic power output. The systems were probed by cyclic voltammetry, pH, UV-Vis spectroscopy and electrochemical impedance spectroscopy, and two competing mechanisms noted, which strongly affect both the current output and Seebeck coefficient (i.e. potential output) of their thermoelectrochemical cells (or thermocells). Green and economic consideration are important aspects if these systems are to be employed in harvesting low-grade heat energy at a larger scale; iron nitrate and acidified iron sulphate were the most highly competitive systems.

AB - Thermogalvanic conversion of temperature gradients into electricity via a redox couple represents a potential method of waste energy harvesting, but inexpensive, effective and sustainable redox couples are required. In this study four aqueous Fe(ii)/Fe(iii) salt systems are considered, based upon ammonium iron sulphate, iron sulphate, iron trifluoromethanesulfonate and iron nitrate. A range of Seebeck coefficients were observed, from +0.18 ± 0.04 mV K-1 for ammonium iron(ii/iii) sulphate to +1.46 ± 0.02 mV K-1 for acidified iron(ii/iii) trifluoromethanesulfonate, both at a temperature difference of 20 K; notably these apparent Seebeck coefficients vary with temperature difference due to significant chemical equilibria. The iron(ii/iii) nitrate system generated the highest thermogalvanic power output. The systems were probed by cyclic voltammetry, pH, UV-Vis spectroscopy and electrochemical impedance spectroscopy, and two competing mechanisms noted, which strongly affect both the current output and Seebeck coefficient (i.e. potential output) of their thermoelectrochemical cells (or thermocells). Green and economic consideration are important aspects if these systems are to be employed in harvesting low-grade heat energy at a larger scale; iron nitrate and acidified iron sulphate were the most highly competitive systems.

UR - http://www.scopus.com/inward/record.url?scp=85057196669&partnerID=8YFLogxK

U2 - 10.1039/c8se00416a

DO - 10.1039/c8se00416a

M3 - Article

VL - 2

SP - 2717

EP - 2726

JO - Sustainable Energy & Fuels

JF - Sustainable Energy & Fuels

SN - 2398-4902

IS - 12

ER -