Highly Sensitive Detection of Redox Species by Current Amplification Using a Thin-Layer Reactor with Boron-Doped Diamond Electrode
At a Glance
Section titled āAt a Glanceā| Metadata | Details |
|---|---|
| Publication Date | 2024-11-22 |
| Journal | ECS Meeting Abstracts |
| Authors | Kana Asai, Atsushi Otake, Yasuaki Einaga |
Abstract
Section titled āAbstractāIn electrode reactions, an electric double layer exists in the nearest region of the electrode surface. And the next layer is a diffusion layer where a concentration gradient is generated by mass transport by diffusion. In a conventional electrochemical cell, a bulk layer exists between the working and counter electrodes. The rate of electrode reaction is limited by the electron transfer at electrode/electrolyte interface as well as the mass transport in the bulk layer. In this study, the thin-layer reactor was fabricated using diamond electrodes with an inter-electrode distance on the order of micrometers. Using the thin-layer reactor, we investigated the reaction mechanism and highly sensitive detection of redox species. Cyclic voltammograms (CVs) in ferrocyanide ([Fe(CN) 6 ] 4- ) solution showed increasing of oxidation current. After that, the oxidation current decreased in the conventional reactor. On the other hand, the thin-layer reactor did not show the current decreasing but the steady current at the oxidative potential(Fig 1). The calibration curve obtained with the thin-layer reactor confirmed the highly sensitive detection of ferrocyanide ([Fe(CN) 6 ] 4- ). In the case of a conventional reactor, the oxidation current was decreased due to lack of supply of Fe (ā ”) species. On the other hand, in the case of the thin-layer reactor, the steady current was observed due to a three-step cycle of (1) consumption of Fe (ā ”) species and formation of Fe (ā ¢) species at the working electrode, (2) regeneration of Fe (ā ”) species at the counter electrode, and (3) resupply of Fe (ā ”) species to the working electrode, cause the steady-state current and highly sensitive detection. Comb array electrodes are reported as an example of highly sensitive detection of redox species. The proximity of the working and counter electrodes is known to contribute the current amplification. In this study, the thin-layer reactor is expected to exhibit even higher detection sensitivity than a comb electrode because it efficiently utilizes the amplification reaction at the counter electrode by completely eliminating the bulk layer. Another advantage of the thin-layer reactor is the simple fabrication with large area electrodes compared with the comb array electrodes. In addition, electrochemical behavior with different counter electrode materials is discussed. Figure 1