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Electroactive Species (electroactive + species)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Complete Elucidation of Electrode Reaction Mechanisms by Using Differential Pulse Polarography

ELECTROANALYSIS, Issue 17-18 2010
Miguel, Rodríguez Mellado
Abstract By exploring the different parameters of the technique, it is shown that Differential Pulse Polarography (DPP) can be used for the elucidation of the reaction mechanisms of the electrochemical processes (with the evident exception of the product and intermediate identification). So, the type of transport towards or from the electrode can be identified from the dependence of the intensities with the pulse amplitude, the electrochemical reaction order with respect to the electroactive species from the shape of the polarogram, the type of rate-determining step from the dependence of the peak potentials on the pulse duration, the electrochemical reaction order with respect to other species, such as the H+ion, from the dependence of the peak potentials on their concentrations etc. [source]

Palladium Sub-Nanoparticle Decorated ,Bamboo' Multi-Walled Carbon Nanotubes Exhibit Electrochemical Metastability: Voltammetric Sensing in Otherwise Inaccessible pH Ranges

ELECTROANALYSIS, Issue 24 2006
Xiaobo Ji
Abstract A generic approach for the detection of electroactive species in potential ranges that would normally be inhibited due to the stripping of the electrocatalytic material is presented. We demonstrate, via the example of the electrochemical oxidation of hydrazine, that palladium nanoparticle (< 1,nm) decorated bamboo multi-walled carbon nanotubes exhibit a metastability such that they allow the sensing of hydrazine in the pH range where palladium metal would normally be voltammetrically stripped (oxidized) from the surface of convectional electrodes. [source]

A Dual-Electrode Approach for Highly Selective Detection of Glucose Based on Diffusion Layer Theory: Experiments and Simulation

CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2005
Kang Wang Dr.
Abstract A dual-electrode configuration for the highly selective detection of glucose in the diffusion layer of the substrate electrode is presented. In this approach, a glassy carbon electrode (GCE, substrate) modified with a conductive layer of glucose oxidase/Nafion/graphite (GNG) was used to create an interference-free region in its diffusion layer by electrochemical depletion of interfering electroactive species. A Pt microelectrode (tip, 5 ,m in radius) was located in the diffusion layer of the GNG-modified GCE (GNG-G) with the help of scanning electrochemical microscopy. Consequently, the tip of the electrode could sense glucose selectively by detecting the amount of hydrogen peroxide (H2O2) formed from the oxidization of glucose on the glucose oxidase layer. The influences of parameters, including tip,substrate distance, substrate potential, and electrolyzing time, on the interference-removing efficiency of this dual-electrode approach have been investigated systematically. When the electrolyzing time was 30 s, the tip,substrate distance was 1.8,a (9.0 ,m) (where a is the radius of the tip electrode), the potentials of the tip and substrate electrodes were 0.7 V and 0.4 V, respectively, and a mixture of ascorbic acid (0.3,mM), uric acid (0.3,mM), and 4-acetaminophen (0.3,mM) had no influence on the glucose detection. In addition, the current,time responses of the tip electrode at different tip,substrate distances in a solution containing interfering species were numerically simulated. The results from the simulation are in good agreement with the experimental data. This research provides a concept of detection in the diffusion layer of a substrate electrode, as an interference-free region, for developing novel microelectrochemical devices. [source]

The Use of Optical Fiber Bundles Combined with Electrochemistry for Chemical Imaging

CHEMPHYSCHEM, Issue 2 2003
Sabine Szunerits Dr.
Abstract The present Review describes the progress made in using imaging optical fiber bundles for fluorescence and electrochemical-initiated chemiluminescence imaging. A novel optoelectrochemical micro-ring array has been fabricated and demonstrated for concurrent electrochemical and optical measurements. The device comprises optical fibers coated with gold via electroless gold deposition and assembled in a random array format. The design yielded an array of approximately 200 micro-ring electrodes, where interdiffusional problems were minimized. The inner diameter of the ring electrode is fixed by the diameter of the individual optical fibers (25 ,m), while the outer radius is determined by the thickness of the deposited gold. While all the fibers are optically addressable, they are not all electrochemically addressable. The resolution of this device is in the tens of micrometers range, determined by the diameter of the optical fiber (25 ,m) and by the spacing between each electrically connected fiber. For the purpose of having well-behaved microelectrode characteristics, this spacing was designed to be larger than 60 ,m. The array was characterized using ferrocyanide in aqueous solution as a model electroactive species to demonstrate that this microelectrode array format exhibits steady-state currents at short response times. This device has potential application to be used as an optoelectronic sensor, especially for the electrolytic generation and transmission of electrochemiluminescence, and was used to demonstrate that electrochemically generated luminescent products can be detected with the fiber assembly. [source]