Electrochemical Cells – New Advances in Fundamental Researches and Applications

ELECTROCHEMICAL CELLS – NEW ADVANCES IN FUNDAMENTAL RESEARCHES AND APPLICATIONS Edited by Yan Shao Electrochemical Cells – New Advances in Fundamental Researches and Applications Edited by Yan Shao Published by InTech Janeza Trdine 9, 51000 Rijeka, Croatia Copyright © 2012 InTech All chapters are Open Access distributed under the Creative Commons Attribution 3.0 license, which allows users to download, copy and build upon published articles even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. After this work has been published by InTech, authors have the right to republish it, in whole or part, in any publication of which they are the author, and to make other personal use of the work. Any republication, referencing or personal use of the work must explicitly identify the original source. As for readers, this license allows users to download, copy and build upon published chapters even for commercial purposes, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications. Notice Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published chapters. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials, instructions, methods or ideas contained in the book. Publishing Process Manager Oliver Kurelic Technical Editor Teodora Smiljanic Cover Designer InTech Design Team First published February, 2012 Printed in Croatia A free online edition of this book is available at www.intechopen.com Additional hard copies can be obtained from [email protected] Electrochemical Cells – New Advances in Fundamental Researches and Applications, Edited by Yan Shao p. cm. ISBN 978-953-51-0032-4 Contents Preface IX Part 1 New Advances in Fundamental Research in Electrochemical Cells 1 Chapter 1 A Review of Non-Cottrellian Diffusion Towards Micro- and Nano-Structured Electrodes 3 Katarína Gmucová Chapter 2 Modeling and Quantification of Electrochemical Reactions in RDE (Rotating Disk Electrode) and IRDE (Inverted Rotating Disk Electrode) Based Reactors 21 Lucía Fernández Macía, Heidi Van Parys, Tom Breugelmans, Els Tourwé and Annick Hubin Chapter 3 Electrochemical Probe for Frictional Force and Bubble Measurements in Gas-Liquid-Solid Contactors and Innovative Electrochemical Reactors for Electrocoagulation/Electroflotation 45 Abdel Hafid Essadki Chapter 4 Electrochemical Cells with the Liquid Electrolyte in the Study of Semiconductor, Metallic and Oxide Systems 71 Valery Vassiliev and Weiping Gong Part 2 Recent Developments for Applications of Electrochemical Cells 103 Chapter 5 Cold Plasma – A Promising Tool for the Development of Electrochemical Cells 105 Jacek Tyczkowski Chapter 6 Fuel Cell: A Review and a New Approach About YSZ Solid Oxide Electrolyte Deposition Direct on LSM Porous Substrate by Spray Pyrolysis 139 Tiago Falcade and Célia de Fraga Malfatti VI Contents Chapter 7 Investigations of Intermediate-Temperature Alkaline Methanol Fuel Cell Electrocatalysis Using a Pressurized Electrochemical Cell 161 Junhua Jiang and Ted Aulich Chapter 8 Electrochemical Cells with Multilayer Functional Electrodes for NO Decomposition 179 Sergey Bredikhin and Masanobu Awano Chapter 9 Sequential Injection Anodic Stripping Voltammetry at Tubular Gold Electrodes for Inorganic Arsenic Speciation 203 José A. Rodríguez, Enrique Barrado, Marisol Vega, Yolanda Castrillejo and José L.F.C. Lima Chapter 10 Electrode Materials a Key Factor to Improve Soil Electroremediation 219 Erika Méndez, Erika Bustos, Rossy Feria, Guadalupe García and Margarita Teutli Preface According to the definition, electrochemical cells are the devices transferring electrical energy from chemical reactions into electricity, or helping chemical processes through the introduction of electrical energy or electrical field. A common example in this category is battery, which has evolved into a big family and is currently used in all kinds of applications. As a relatively old scientific topic, the concept and application of electrochemical cells has been invented and utilized by human society has a long history. With the advance of modern science and technology, the research field of electrochemical cells has been more and more involved in the emerging areas of nano-technology, bio-technology, and novel energy storage and conversion systems, especially when serious attentions have been paid to energy, health, and environmental issues for modern industrial society. It has become useful and necessary to summarize the new advances in both fundamental and practical researches in this field when we want to review the new development in recent years. In this book, parallel efforts have been put on both new advances in fundamental research and recent developments for applications of electrochemical cells, which include electrode design, electrochemical probe, liquid electrolytes, fuel cells, electrochemical detectors for health and environment consideration. Of course, electrochemical cells have been developed into a relatively large research category, which also means this book can only cover a corner of these topics. Yan Shao, Center for Polymers and Organic Solids, Mitsubishi Chemical Center for Advanced Materials, University of California, Santa Barbara, USA Part 1 New Advances in Fundamental Research in Electrochemical Cells 1 A Review of Non-Cottrellian Diffusion Towards Micro- and Nano-Structured Electrodes Katarína Gmucová Institute of Physics, Slovak Academy of Sciences Slovak Republic 1. Introduction The past few decades have seen a massive and continued interest in studying electrochemical processes at artificially structured electrodes. As is well known, the rate of redox reactions taking place at an electrode depends on both the mass transport towards the electrode surface and kinetics of electron transfer at the electrode surface. Three modes of mass transport can be considered in electrochemical cells: diffusion, migration and convection. The diffusional mass transport is the movement of molecules along a concentration gradient, from an area of high concentration to an area of low concentration. The migrational mass transport is observed only in the case of ions and occurs in the presence of a potential gradient. Convectional mass transport occurs in flowing solutions at rotating disk electrodes or at the dropping mercury electrode. In 1902 Cottrell derived his landmark equation describing the diffusion current, I, flowing to a planar, uniformly accessible and smooth electrode of surface area, A, large enough not to be seriously affected by the edge effect, in contact with a semi-infinite layer of electrolyte solution containing a uniform concentration, cO, of reagent reacting reversibily and being present as a minor component with an excess supporting electrolyte under unstirred conditions, during the potential-step experiment (Cottrell, 1902) D InFAc , (1) O t where n is the number of electrons entering the redox reaction, F is the Faraday constant, D is the diffusion coefficient, and t is time. It has long been known that the geometry, surface structure and choice of substrate material of an electrode have profound effects on the electrochemical response obtained. It is also understood that the electrochemical response of an electrode is strongly dependent on its size, and that the mass transport in electrochemical cell is affected by the electrode surface roughness which is generally irregular in both the atomic and geometric scales. Moreover, the instant rapid development in nanotechnology stimulates novel approaches in the preparation of artificially structured electrodes. This review seeks to condense information on the reasons giving rise or contributing to the non-Cottrellian diffusion towards micro- and nano structured electrodes. 4 Electrochemical Cells – New Advances in Fundamental Researches and Applications 2. Electrode geometry Cottrell equation, derived for a planar electrode, can be applied to electrodes of other simple geometries, provided that the temporal and spatial conditions are such that the semi-infinite diffusion to the surface of the electrode is approximately planar. However, in both the research and application spheres various electrode geometries are applied depending on the problem or task to be solved. Most electrodes are impaired by an ‘‘edge effect’’ of some sort and therefore do not exhibit uniform accessibility towards diffusing solutes. Only the well defined electrode geometry allows the data collected at the working electrode to be reliably interpreted. The diffusion limited phenomena at a wide variety of different electrode geometries have been frequently studied by several research teams. Aoki and Osteryoung have derived the rigorous expressions for diffusion-controlled currents at a stationary finite disk electrode through use of the Wiener-Hopf technique (Aoki & Osteryoung, 1981). The chronoamperometric curve they have obtained varies smoothly from a curve represented by the Cottrell equation and can be expressed as the Cottrell term multiplied by a power series in the parameter Dt r , where r is the electrode radius. Later, a theoretical basis for understanding the microelectrodes with size comparable with the thickness

Load more