Electrochemistry of Carbon Electrodes

Richard C. Alkire, Philip N. Bartlett, Jacek Lipkowski, Richard C. Alkire, Philip N. Bartlett, Jacek Lipkowski

• Publisher: Wiley-VCH
• Year: 2015
• Print ISBN:
  9783527337323
• eBook ISBN:
  9783527697502
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Physical & Theoretical Chemistry

The book sets the standard on carbon materials for electrode design. For the first time, the leading experts in this field summarize the preparation techniques and specific characteristics together with established and potential applications of the different types of carbon-based electrodes. An introductory chapter on the properties of carbon together with chapters on the electrochemical characteristics and properties of the different modifications of carbon such as carbon nanotubes, graphene, carbon fiber, diamond or highly ordered pyrolytic graphite provide the reader with the basics on this fascinating and ubiquitous electrode material. Cutting-edge technologies such as carbon electrodes in efficient supercapacitors, Li-ion batteries and fuel cells, or electrodes prepared by screen-printing are discussed, giving a complete but concise overview about the topic. The clearly structured book helps newcomers to grasp easily the principles of carbon-based electrodes, while researchers in fundamental and applied electrochemistry will find new ideas for further research on related key technologies.

Chapter 1
Properties of Carbon: An Overview

Shengxi Huang, Johan Ek Weis, Sara Costa, Martin Kalbac and Mildred S. Dresselhaus

1.1 Overview of Properties

Carbon (element No. 6 in the periodic table) forms a variety of materials, including graphite, diamond, carbon fibers, charcoal, as well as newly discovered nanocarbon materials, such as fullerene, graphene, carbon nanotube, and graphene nanoribbon (GNR). Even though all are composed of the same atoms, different carbon materials can show very different physical and chemical properties, including electrical transport, optical and thermal properties, and chemical reactivity, depending on their structures.

Electrochemistry has been connected to carbon materials since the early days of electrochemistry research [1], and the discoveries of new carbon materials in the past decades have been accompanied by research advances concerning the doping of these materials using electrochemical techniques, with an emphasis on materials preparation, characterization, and applications.

Among the electrochemical techniques and characterization tools, vibrational and optical spectroscopies have been important. Electrochemical charge transfer, an important process in electrochemistry, influences not only the electronic structure of the materials but also their vibrational and optical properties, which are all dependent on the concentration of electrons and holes found in the solid. Therefore, valuable data can be obtained when electrochemistry and in situ Raman spectroscopy are applied simultaneously under the heading of spectroelectrochemistry. Such investigations have been carried out extensively on carbon nanomaterials in order to investigate the effects of electron and hole doping.

One advantage of electrochemistry over other experimental techniques is its ability to introduce higher levels of dopants and to make quantitative, reproducible measurements [2, 3]. The electrochemical setup including the choice of the particular electrolyte is an important factor that influences the doping efficiency in spectroelectrochemical experiments. Different electrolytes can thereby require larger electrode potentials than others to achieve the same doping levels, so that attention needs to be given to the choice of the electrolyte for studying a given material system. Failures to pay attention to such issues have, in the past, led to apparent inconsistencies between different sets of published data.

The basic carbon material introduced in this chapter is graphene, which is a single layer of crystalline graphite, because it is the basic building block behind sp² carbon materials. Graphite, which represents nature's way to build up stacks of graphene layers into a bulk crystal, is then introduced briefly, together with the synthetic commercial product, highly oriented pyrolytic graphite (HOPG), which closely resembles graphite. Another commonly used nanocarbon material, carbon nanotube, is also discussed, which has deep scientific interest, and is also interesting along with its related carbon fiber analog for electrochemical commercial applications. Porous carbon is an sp² carbon material useful for applications requiring a huge surface area, and is also discussed briefly. Diamond, which is commonly a symbol of societal wealth and prestige, is gaining more and more scientific attention recently due to its extraordinary properties in electrochemistry, quantum physics, and biology, and has promising applications in all of these fields. Finally, brief mention is made of other sp² nanocarbon materials with significant current scientific interest, carbon nanoribbons and porous carbon, and these materials may someday find interest for electrochemical science and applications.

In this chapter, we will introduce some typical carbon materials that are widely studied in electrochemistry. Their properties, not restricted to their electrochemical properties, will be briefly described. Some characterization techniques, including spectroelectrochemistry, will be described when applied to selected carbon materials. A brief overview of the application of various carbon materials to electrochemistry will be included in this chapter, which will be concluded by an outlook to the future.

1.2 Different Forms of Carbon

1.2.1 Graphene

1.2.1.1 Optical Properties

It is widely established that graphene has numerous fascinating properties [4–9]. Though considered as a semimetal, graphene has unique electromagnetic/plasmonic effects compared to conventional noble metals [10, 11]. First, its plasma frequency in the long-wavelength limit is expressed as [12–15]

where

is the Fermi energy of graphene,

is the universal optical conductivity of graphene and is independent of any material parameters:

[16, 17],

is the unit charge, and

is the permittivity. Note that the expression of plasma frequency for graphene is very different from that for metals which is [18]

where

is the carrier density in graphene and

is the carrier effective mass. We can see that

and

. Such a difference in the plasma frequencies between graphene and metals is due to the Dirac fermions in graphene, rather than to ordinary Schrödinger fermions in normal metals. The plasma frequency of graphene is in the terahertz range, which is 10³ times lower than

in metals, and which can be tuned through gating or doping [11, 19, 20], or by fabricating graphene ribbons with micron widths (see Figure 1.1), where

is in the terahertz range. Here,

differs with the ribbon widths and with the Fermi energy

, as shown in Figure 1.1. Second, single-layer graphene has a lin...

Table of contents

• Cover
• Advances in Electrochemical Science and Engineering
• Title Page
• Copyright
• Table of Contents
• List of Contributors
• Series Editors Preface
• Preface
• Chapter 1: Properties of Carbon: An Overview
• Chapter 2: Electrochemistry at Highly Oriented Pyrolytic Graphite (HOPG): Toward a New Perspective
• Chapter 3: Electrochemistry in One Dimension: Applications of Carbon Nanotubes
• Chapter 4: Electrochemistry of Graphene
• Chapter 5: The Use of Conducting Diamond in Electrochemistry
• Chapter 6: Modification of Carbon Electrode Surface
• Chapter 7: Carbon Materials in Low–Temperature Polymer Electrolyte Membrane Fuel Cells
• Chapter 8: Electrochemical Capacitors Based on Carbon Electrodes in Aqueous Electrolytes
• Chapter 9: Carbon Electrodes in Electrochemical Technology
• Chapter 10: Carbon Electrodes in Molecular Electronics
• Chapter 11: Carbon Paste Electrodes
• Chapter 12: Screen-Printed Carbon Electrodes
• Index
• End User License Agreement