Cyclic voltammetric studies of nitrate and nitrite ion reduction at the surface of iridium-modified carbon fiber electrode

Dibyendu De, James Douglas Englehardt, Egwu Eric Kalu

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Abstract

The electroreduction of nitrate and nitrite on iridium-deposited carbon fiber electrode in aqueous sodium perchlorate solutions of pH 7 was studied using cyclic voltammetric techniques. Results obtained on the modified electrode support a two-step nitrate reduction mechanism in which nitrate is first reduced to nitrite at Epeak = -800 mV (Ag/AgCl) during the negative scan and further reduced to ammonia at Epeak = -775 mV (Ag/AgCl) during the anodic scan. An oxidation peak for the unreduced nitrite was observed at -300 mV (Ag/AgCl). A Tafel slope of approximately 178 mV/dec and a pseudo-first-order rate constant of k° = 4.18×10-7 cm s-1 were determined for the cathodic reduction peak while Tafel slope of 18.9 mV/dec and k° = 2.62×10-23 cm s-1 were obtained for the anodic reduction peak. The Tafel slopes obtained also support the two-step mechanism. The results obtained strongly suggest a minimal effect of pH on nitrate reduction in the pH range of 2.0-13.0 in NaClO4 solution at the surface of iridium-coated carbon fiber electrode.

Original languageEnglish
Pages (from-to)4224-4228
Number of pages5
JournalJournal of the Electrochemical Society
Volume147
Issue number11
DOIs
StatePublished - Nov 1 2000

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Iridium
nitrites
Nitrites
carbon fibers
iridium
Nitrates
Carbon fibers
nitrates
Ions
Electrodes
electrodes
slopes
ions
perchlorates
Ammonia
ammonia
Rate constants
Sodium
sodium
Oxidation

ASJC Scopus subject areas

  • Electrochemistry
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

Cite this

Cyclic voltammetric studies of nitrate and nitrite ion reduction at the surface of iridium-modified carbon fiber electrode. / De, Dibyendu; Englehardt, James Douglas; Kalu, Egwu Eric.

In: Journal of the Electrochemical Society, Vol. 147, No. 11, 01.11.2000, p. 4224-4228.

Research output: Contribution to journalArticle

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AB - The electroreduction of nitrate and nitrite on iridium-deposited carbon fiber electrode in aqueous sodium perchlorate solutions of pH 7 was studied using cyclic voltammetric techniques. Results obtained on the modified electrode support a two-step nitrate reduction mechanism in which nitrate is first reduced to nitrite at Epeak = -800 mV (Ag/AgCl) during the negative scan and further reduced to ammonia at Epeak = -775 mV (Ag/AgCl) during the anodic scan. An oxidation peak for the unreduced nitrite was observed at -300 mV (Ag/AgCl). A Tafel slope of approximately 178 mV/dec and a pseudo-first-order rate constant of k° = 4.18×10-7 cm s-1 were determined for the cathodic reduction peak while Tafel slope of 18.9 mV/dec and k° = 2.62×10-23 cm s-1 were obtained for the anodic reduction peak. The Tafel slopes obtained also support the two-step mechanism. The results obtained strongly suggest a minimal effect of pH on nitrate reduction in the pH range of 2.0-13.0 in NaClO4 solution at the surface of iridium-coated carbon fiber electrode.

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