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Journal of Applied Electrochemistry

, Volume 24, Issue 2, pp 107–113 | Cite as

Oxidation of iodide to iodate concurrently with evolution of oxygen at Kelgraf composite electrodes

  • J. E. Vitt
  • D. C. Johnson
Papers

Abstract

The oxidation of I to IO 3 in acidic media occurs at numerous electrode materials at potential values corresponding to the anodic discharge of H2O with simultaneous evolution of oxygen. In the study reported here the anodic current density for IO 3 production was measured by difference voltammetry at rotated disc electrodes (r.d.e.'s) constucted from pure glassy carbon (GC) and Kelgraf (graphite plus Kel-F) composite materials. These signal values (S) were normalized relative to the background current (B) for oxygen evolution measured at 1.75 V vs SCE, a potential corresponding to the transport-limited production of IO 3 at GC. Despite a small positive shift in E1/2 with decreasing fractional active area, the signal-to-background ratio (S/B) at the Kelgraf electrodes was enhanced relative to that for the GC electrode. For example, SIB at a 2% Kelgraf r.d.e. was nine times larger than at a GC r.d.e. This corresponds to an increase in current efficiency (S/(S + B)) for IO 3 production from about 50% at the GC r.d.e. to about 90% at 2% Kelgraf r.d.e. This is explained on the basis of (i) a significant decrease in total background current as a result of the decreased fraction of the Kelgraf surface that corresponds to carbon, and (ii) a larger flux density of I at the carbon microelectrodes in the Kelgraf r.d.e., as compared to the GC r.d.e., as a result of radial diffusion, i.e. the so-called ‘edge effect’.

Keywords

Glassy Carbon Glassy Carbon Electrode Oxygen Evolution Current Efficiency Composite Electrode 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman & Hall 1994

Authors and Affiliations

  • J. E. Vitt
    • 1
  • D. C. Johnson
    • 2
  1. 1.Department of ChemistryUniversity of South DakotaVermillionUSA
  2. 2.Department of Chemistry and Ames LaboratoryIowa State UniversityAmesUSA

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