Ultrafast Electrochemical Techniques
Published Online: 15 SEP 2006
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Forster, R. J. 2006. Ultrafast Electrochemical Techniques. Encyclopedia of Analytical Chemistry. .
- Published Online: 15 SEP 2006
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Ultrafast electrochemical techniques provide information about the kinetics and thermodynamics of redox processes that occur at submillisecond or even nanosecond timescales. This short timescale is achieved either by making very rapid transient measurements or by using ultrasmall probes to achieve very high rates of diffusion under steady-state conditions. Microelectrodes (i.e. electrodes with critical dimensions in the micrometer range) play pivotal roles in both approaches. Electrochemistry has several advantages over spectroscopy in that it provides direct information about electron transfer (E) and coupled chemical (C) reactions. Ultrafast electrochemical techniques now allow it to do so at times as short as 10 ns. In transient measurements, decreasing the lower accessible timescale depends critically on fabricating ultramicroelectrodes that continue to respond ideally as their critical dimension (e.g. the radius of a microdisc) decreases. It is now possible to assemble microelectrodes that respond to changes in applied potential within less than a few nanoseconds. In steady-state approaches, ultrasmall probes are required to make short timescale measurements and various approaches that yield nanodes (i.e. electrodes of nanometer dimension) have been proposed. However, beyond the need for smaller probes and faster instrumentation, the continued development of new theory describing electron transfer is essential, where the dimensions of the zone that is depleted of reactant because of a Faradaic reaction and the electrochemical double layer become comparable.