Applications of Graphene and Graphene-Oxide based Nanomaterials

Sekhar Ray

• Publisher: William Andrew
• Year: 2015
• Print ISBN: 9780323375214
• eBook ISBN: 9780323375221
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

Carbon nanomaterials have a unique place in Nanoscience owing to their exceptional electrical, thermal, chemical and mechanical properties and have found application in areas as diverse as composite materials, energy storage and conversion, sensors, drug delivery, field emission devices and nano-scale electronic components. Conjugated carbon nanomaterial covers the areas of carbon nanotubes, fullerenes and graphene. Graphene is the newest of the carbon nanomaterials and promises to be a very active field. Already since its isolation in 2004 it has grabbed the attention of the chemistry, materials and physics communities. It promises to rival carbon nanotubes in terms of properties and potential applications with the number of publications rising from ca. 130 in 2005 to ca. 2,800 in 2010. In this short book Sekhar Ray gives an overview on graphene and graphene-oxide with a strong focus on applications. Structured in three chapters, one on graphene, one on graphene-oxide and one on graphene based nanoparticles his resource describes in each chapter the preparation (including synthesis and functionalization) and material properties before detailing a whole range of applications. Ray finishes each chapter with information on remaining challenges and perspectives. - Written by an expert in the field who, during his last 17 years of research, has published more than 80 peer reviewed articles in recognized international journals - Gives full-chapter overviews on Graphene, Graphene-Oxide, and Graphene based nanoparticles - Focusses on applications

Chapter 1

Application and Uses of Graphene

Sekhar C. Ray, Department of Physics, College of Science, Engineering and Technology, University of South Africa, Florida Park, Johannesburg, South Africa

Graphene represents a conceptually new class of promising material that is only one atom thick and, on this basis, offers new roads into low-dimensional physics. It never ceases to surprise and it continues to provide a fertile ground for different applications. This two-dimensional material exhibits exceptionally high crystal and electronic quality and has several potential applications. Research work regarding graphene is rapidly increasing in materials science, condensed matter physics, and solid-state physics. Graphene and graphene-based materials have attracted great attention because of their unique properties of high mechanical flexibility, large surface area, chemical stability, and superior electric and thermal conductivities that render them great choices for fabricating different devices and for use in different applications. In this chapter, the recent progress in graphene and graphene-based materials for different electronic, optoelectronic, and other applications is presented.

Keywords

Graphene; preparation of graphene; properties of graphene; applications of graphene; perspectives of graphene

1.1 Introduction

Carbon has many different forms, namely diamond, graphite, and amorphous carbon. Diamond and graphite are well-known allotropes of carbon known since ancient times. Fullerene, the third form of carbon, was discovered in 1985 by Kroto et al., and carbon nanotubes (CNTs) were discovered in 1991 by Iijima; subsequently, it has become very important in the science and technology communities. Thus, only three-dimensional (3D) (diamond and graphite), one-dimensional (1D; CNTs), and zero-dimensional (0D; fullerenes) allotropes of carbon were known in the carbon community. Although it was realized in 1991 that CNTs were formed by rolling of a two-dimensional (2D) graphene sheet, with a single layer from 3D graphitic crystal, the isolation of graphene was quite elusive, resisting any attempt regarding its experimental research work until 2004. Graphene is the basic structural element of some carbon allotropes, including graphite, CNTs, and fullerenes. Fullerene is entirely composed of carbon in the form of spherical shapes called bucky balls, whereas CNTs have tubular arrangements. For more than two decades, fullerene and CNTs-based materials enjoyed widespread applications in diverse fields of research such as electronics, batteries, super-capacitors, fuel cells, electrochemical sensors, biosensors, and medicinal applications.

Currently, graphene is becoming a “rising star” material after its successful production by a simple scotch tape approach using readily available graphite in 2004 by Andre Geim and his coworkers. Graphene comprises a single-layer sheet of sp² bonded carbon atoms with densely packed honeycomb crystal lattice. Its exceptional properties such as high surface area, room temperature Hall effect, tunable band gap, and excellent electrical, thermal, and conducting properties offer a versatile platform for its use as active material in the preparation of various composite materials (Novoselov et al., 2004). Numerous efforts were made to review the structure, preparation, properties, and applications of graphene and its composite materials (Geim, 2009; Rao et al., 2009; Neto et al., 2009; Allen et al., 2010). Currently, graphene is one of the most popular materials; it can be applied for various devices and applications due to its outstanding properties. This chapter presents the different uses and applications of graphene, and the synthesis process and different outstanding properties are also discussed briefly.

1.2 Preparation/Synthesis of Graphene

Several methods have already been established for producing different kinds of graphene materials. Micromechanical exfoliation, chemical vapor deposition, epitaxial growth, arc discharge method, intercalation methods in graphite, unzipping of CNTs, and electrochemical and chemical methods were some of the important preparation methods available for the preparation of graphene. Chemical methods involve strong oxidation of graphite and subsequent reduction to graphene by reducing agents. A novel synthesis by dichromate oxidation of graphite followed chemical reduction with hydrazine, which is also used for the preparation of graphene (Chandra et al., 2010). Kumar et al. (2013) reported the preparation of nitrogen-doped graphene by microwave plasma chemical vapor deposition method. Electrophoretic deposition (EPD) is one of the interesting techniques for synthesizing a nanosheet of graphene. Chen et al. (2010) deposited graphene sheets onto nickel foams via EPD approach. Ata et al. (2012) prepared graphene by EPD method with aluminon as an organic charging and film-forming agent. Graphene could be prepared by direct current arc-discharge method in the presence of hydrogen atmospheric pressure using graphite rods as electrodes for the deposition (Guo et al., 2012). Laser pyrolysis technique has been demonstrated to synthesize multilayer graphene in the presence of dilution gas (Florescu et al., 2013). Among these methods, chemical vapor deposition methods (plasma-enhanced CVD/thermal CVD) are efficient approaches for the synthesis of graphene. However, each method has its own advantages and disadvantages. Among all of these methods, CVD method is efficient for the production of graphene materials for different applications. Graphene, produced in this method, was found to have better crystallinity than that formed with any other method. PECVD method has shown the versatility of synthesizing graphene on any substrate, thus expanding its field of applications.

1.3 Properties of Graphene

The bond length of the C–C bond in graphene is ~1.42 Å, with a strong bond in a particular layer but weak bonding between layers. The specific surface area of a single sheet of graphene is ~2630 m²/g (Stoller et al., 2008). Graphene has unique and outstanding optical properties (>97.7% transmittance), with a band gap value of ~0–0.25 eV (Zhang et al., 2009). Some other fascinating characteristics include high carrier mobility (~200,000 cm²/Vs) (Geim and Novoselov, 2007) and high Young’s modulus (1.0 TPa). Graphene and its composite materials can be used as semi-conductors because of their extraordinary conducting properties. Graphene has been envisioned as the building block of all other important graphitic allotrope forms: fullerene-wrapped version of graphene; CNT-rolled version of graphene; and graphite-stacked version of graphene. Enoki et al. (2005) investigated the unique magnetic properties of nanographene, such as spin glass states, magnetic switching, and edge-state spin gas probing, for the possible applications in electronic and magnetic devices. Chen, S. et al. (2012) reported brief experimental studies about the isotope effects on the thermal properties of graphene and found that the ratios of ¹²C and ¹³C play an important role in the thermal conductivity of graphene (Chen, S. et al., 2012). All these extraordinary properties of graphene have led to its inherent use for real applications.

Some of the potential properties are as follows:

• High Young’s modulus ~1000 Gpa

• Effective moisture barrier

• Electrical conductivity similar to copper

• Density four-times lower than copper

• Thermal conductivity five-times that of copper

• Essentially an opened up CNT; high surface area of ~2500 m²/g

• Lower density than steel but can be up to 50-times stronger

However, for a quick reference regarding the synthesis of graphene during different processes and grown/synthesized on different substrates, studies of their different properties using different measurements including their advantages/disadvantages are listed in Tables 1.1 and 1.2 (Soldano et al., 2010).

Table 1.1

Advantages and Disadvantages for Techniques Currently Used to Produce Graphene

	Advantages	Disadvantages
Mechanical exfoliation	(i) Low cost and easy (ii) No special equipment needed, (iii) SiO2 thickness is tuned for better contrast	(i) Serendipitous (ii) Uneven films (iii) Labor intensive (not suitable for large-scale production)
Epitaxial growth	(i) Most even films (of any method) (ii) Large-scale area	(i) Difficult control of morphology and adsorption energy (ii) High-temperature process
Graphene oxide	(i) Straightforward upscaling (ii) Versatile handling of the suspension (iii) Rapid process	(i) Fragile stability of the colloidal dispersion (ii) Reduction to graphene is only partial

Source: Reproduced with permission (Soldano et al., 2010). Copyright 2015 Elsevier.

Table 1.2

Synoptic Table of the Graphene Growth Methods on Both Metals and Carbides Substrates^a

Substrate		Growth Condition (gas, T, exposure)	Experiment Techniques	Edges	Comment (aC=0.245 nm)	Reference
Metals	Pt(111)	Benzene (C6H6), T=1000 K. 1–5L→ nongraphitic film; >5L→ full coverage	STM, LEED, AES	Hexagonal arrangeme...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Acknowledgments
• Chapter 1. Application and Uses of Graphene
• Chapter 2. Application and Uses of Graphene Oxide and Reduced Graphene Oxide
• Chapter 3. Graphene-Based Carbon Nanoparticles for Bioimaging Applications