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

Dibyendu De, James D. Englehardt, Egwu Eric Kalu

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


ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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