Scanning electrochemical microscopy - Kinetics of chemical reactions following electron-transfer measured with the substrate-generation-tip-collection mode
UNSPECIFIED (1998) Scanning electrochemical microscopy - Kinetics of chemical reactions following electron-transfer measured with the substrate-generation-tip-collection mode. JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS, 94 (6). pp. 753-759. ISSN 0956-5000Full text not available from this repository.
The substrate-generation-tip-collection (SG-TC) mode of the scanning electrochemical microscope (SECM) is used as a new approach to investigate the kinetics of EC processes. Under the conditions of interest, a species O is generated at a macroscopic substrate (generator) electrode, with potential-step control, through the diffusion-limited electrolysis of a solution species R (E step). As O diffuses away from the generator, it undergoes a first order Chemical reaction in solution (C step). A fraction of O is collected by electrolysis back to R at an externally biased ultramicroelectrode (UME), positioned directly over the substrate. This promotes the diffusional feedback of R to the substrate. Theory for the problem, relating the time-dependent tip current response to the rate constant for the C step and the tip-substrate electrode separation is developed numerically. Results of the calculations illustrate how the characteristic features of the tip current transients: peak current, peak time and post-half-peak time, depend on the kinetics of the C step and the inter-electrode separation. It is shown that both the kinetics and tip-substrate separation can be determined independently from a single transient by simply measuring the peak current and peak time. The theoretical results are validated experimentally through model studies of the oxidative deamination of N,N,-dimethyl-p-phenylenediamine(DMPPD) in aqueous solution at high pH. The effective second-order rate constant for the deamination step is in excellent agreement with values measured by alternative methods.
|Item Type:||Journal Article|
|Subjects:||Q Science > QD Chemistry
Q Science > QC Physics
|Journal or Publication Title:||JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS|
|Publisher:||ROYAL SOC CHEMISTRY|
|Date:||21 March 1998|
|Number of Pages:||7|
|Page Range:||pp. 753-759|
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