Electrocatalysis at microelectrodes: Geometrical considerations

Huanfeng Zhu, Yuriy V. Tolmachev, Daniel Alberto Scherson

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

The influence of the shape of individual electrocatalytically active, axisymmetric particles supported on an inactive substrate, on the current associated with heterogeneous redox reactions involving solution-phase species has been examined theoretically. In agreement with previous work, the diffusion-limited currents, ilim, for a disk and supported truncated spheres of the same area including a full sphere are very similar (within ca. 10%) . Large enhancements in the predicted values of ilim were found, however, for spheroids of the prolate type, as the aspect ratio was increased. Analyses of arrays of electrocatalytically active disks embedded in a planar inactive support in the presence of a diffusion boundary layer of well-defined thickness, for example, a rotating disk electrode, revealed that values of ilim very close to those expected for fully catalytic surfaces could be achieved for disk coverages on the order of 1%. Similar conclusions were made for corresponding arrays of small disks embedded in microdisks or spherical inactive supports in quiescent media. This effect might explain observations made for iron porphyrins adsorbed on graphite surfaces in aqueous electrolytes, for which the experimentally determined onset for oxygen reduction is found to be at potentials well ahead of the onset of the voltammetric wave associated with the conversion of the inactive (ferric) to the active (ferrous) form of the macrocycle.

Original languageEnglish
Pages (from-to)13650-13656
Number of pages7
JournalJournal of Physical Chemistry C
Volume114
Issue number32
DOIs
Publication statusPublished - 2010 Aug 19
Externally publishedYes

Fingerprint

Electrocatalysis
Microelectrodes
Phosmet
Graphite
Redox reactions
spheroids
Porphyrins
rotating disks
Rotating disks
porphyrins
Electrolytes
aspect ratio
Aspect ratio
boundary layers
Boundary layers
Iron
graphite
electrolytes
Oxygen
iron

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Surfaces, Coatings and Films
  • Energy(all)

Cite this

Electrocatalysis at microelectrodes : Geometrical considerations. / Zhu, Huanfeng; Tolmachev, Yuriy V.; Scherson, Daniel Alberto.

In: Journal of Physical Chemistry C, Vol. 114, No. 32, 19.08.2010, p. 13650-13656.

Research output: Contribution to journalArticle

Zhu, Huanfeng ; Tolmachev, Yuriy V. ; Scherson, Daniel Alberto. / Electrocatalysis at microelectrodes : Geometrical considerations. In: Journal of Physical Chemistry C. 2010 ; Vol. 114, No. 32. pp. 13650-13656.
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