Natural Convection at Microelectrodes.

Abstract

Steady-state voltammetric currents for Fe(CN)6(-4) oxidation and Fe(CN)6(-3) reduction in 0.2 M KCl solutions are shown to be a function of the orientation of Au and Pt rnicrodisk electrodes (radius = 6.4 to 25 micrometers) with respect to the gravitational field. The observed angular dependencies for the Fe(CN)6(-3/-4) couple are in agreement with theoretical expectations based on electrochemically-generated fluid density gradients within the depletion layer. The results demonstrate that steady-state voltammetric currents measured at microelectrodes are comprised of both diffusional and natural convection mass-transfer fluxes. At 25 micrometers-radius microdisks, natural convection accounts for between 2 and 13% of the total current for redox concentrations between 10 and 500 mM, respectively. The contribution of mass-transfer due to natural convection is shown to rapidly decrease with decreasing electrode size. jg

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Document Details

Document Type
Technical Report
Publication Date
Mar 31, 1995
Accession Number
ADA294338

Entities

People

  • Henry S. White
  • Jeonghee Lee
  • Xiaoping Gao

Organizations

  • University of Utah

Tags

Communities of Interest

  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Analytical Chemistry
  • Aqueous Solutions
  • Cells
  • Chemical Analysis
  • Chemistry
  • Coefficients
  • Convection
  • Diffusion Coefficient
  • Electrochemical Reactions
  • Electrolytes
  • Gravitational Fields
  • Heat Transfer
  • Mass Transfer
  • Measurement
  • Migration
  • Military Research
  • Steady State

Readers

  • Astronomy/Astrophysics
  • Electrochemical Surface Science
  • Mathematics or Statistics