Kinetics of Electron-Transfer Reactions at Nanoelectrodes

Peng Sun and Michael V. Mirkin*
Department of Chemistry and Biochemistry, Queens CollegeCUNY, Flushing, New York 11367
Anal. Chem., 2006, 78 (18), pp 6526–6534
DOI: 10.1021/ac060924q
Publication Date (Web): July 28, 2006
Copyright © 2006 American Chemical Society
*

 To whom correspondence should be addressed. E-mail:  mmirkin@ qc.cuny.edu.

Abstract

The kinetics of several fast heterogeneous electron-transfer reactions were investigated by steady-state voltammetry at nanoelectrodes and scanning electrochemical microscopy (SECM). The disk-type, polished Pt nanoelectrodes (3.7−400-nm radius) were characterized by a combination of voltammetry, scanning electron microscopy, and SECM. A number of experimental curves were obtained at the same nanoelectrode to attain the accuracy and reproducibility similar to those reported previously for micrometer-sized probes. A new analytical approximation was developed and used for analysis of steady-state tip voltammograms. The self-consistent kinetic parameter values with the uncertainty margin of 10% were obtained for electrodes of different radii and for a wide range of the SECM tip/substrate separation distances. The determined standard rate constants are compared to those previously measured at the electrodes of different dimensions, and the correlation between the heterogeneous and self-exchange rate constants is discussed.

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History

  • Published In Issue September 15, 2006
  • Received for review May 19, 2006. Accepted June 26, 2006.

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