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- Herausgeber: Wiley-VCH GmbH
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- Sprache: Englisch
This book provides a state-of-the-art overview of carbon- based and enhanced nanostructured materials from materials synthesis methods, characterization techniques to advanced functionalization techniques. Then it discusses the integration of these materials in various electronic applications for the performance enhancement including non-volatile memories, optoelectronic devices, energy harvesters, actuators, analog and digital electronics and circuits.
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Veröffentlichungsjahr: 2022
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Table of Contents
Cover
Title Page
Copyright
Preface
1 Enhanced Carbon‐Based Materials and Their Applications
1.1 Overview
1.2 Glance of Carbon‐Based Materials
1.3 Applications
1.4 Outline of This Book
References
2 Carbon‐Based Nanomaterials: Synthesis and Characterizations
2.1 Introduction
2.2 Synthesis of Carbon‐Based Nanostructures
2.3 Characterization
2.4 Summary
References
3 Functional Carbon‐Based Nanomaterials and Sensor Applications
3.1 Introduction to Low‐Dimensional Carbon‐Based Nanomaterials
3.2 Modification of Low‐Dimensional Carbon‐Based Nanomaterials
3.3 Plasma‐Based Synthesis of Heteroatom‐Doped Graphene
3.4 Doping Modulation in Graphene for Optoelectronic Applications
3.5 Imperfections in Graphene for Strain–Pressure‐ Sensing Applications
3.6 Structural Defect in Graphene for Gas‐Sensing Applications
References
4 Fabrication Techniques of Resistive Switching Carbon‐Based Memories
4.1 Introduction – Emerging Carbon‐Based Memory Technologies
4.2 Memristor‐Based Memory
4.3 Substrate Options
4.4 Effect of Electrode Materials
4.5 Fabrication Methods of Metal/Insulator/Metal Structure
4.6 Conclusion
References
5 Carbonous‐Based Optoelectronic Devices
5.1 Introduction
5.2 Graphene‐Based Optoelectronics
5.3 Carbonous Materials in Photovoltaics
5.4 Carbonous Materials in Dye‐Sensitized Solar Cells
5.5 Carbonous Materials in Perovskite Solar Cells (PSCs)
References
6 Thermoelectric Energy Harvesters and Applications
6.1 Introduction
6.2 Thermoelectric Effect and Properties
6.3 Thermoelectric Power and Efficiency
6.4 Thermoelectric Materials
6.5 Application of Organic Thermoelectric Generators
6.6 Summary/Future Perspective
References
7 Carbon‐Enhanced Piezoelectric Materials and Applications
7.1 Introduction
7.2 Carbon‐Enhanced Piezoelectric Materials
7.3 Fabrication Methods
7.4 Applications
7.5 Conclusion
Acknowledgment
References
8 Actuators Based On the Carbon‐Enhanced Materials
8.1 Introduction
8.2 Actuation on the Molecular Scale
8.3 Carbon Nanomaterials
8.4 Carbon‐Based Actuation
8.5 Challenges and Prospectives of Actuators Based on Carbon Nanostructures
References
9 Display Based on Carbon‐Enhanced Materials
9.1. Introduction
9.2. Display Based on CDs
9.3. Display Based on Carbon Nanotubes
9.4. Display Based on Graphene and Graphene Oxide
9.5. Summary and Outlook
References
10 Enhanced Carbon‐Based Materials and Their Applications
References
Index
End User License Agreement
List of Tables
Chapter 2
Table 2.1 Summary of some variation of carbon nanostructures properties....
Table 2.2 Precursor for the synthesis of carbon nanomaterials from differen...
Table 2.3 Summary of the related works used thermal CVD for synthesis of ca...
Table 2.4 Variation of Raman D and G peak position and
I
D
/
I
G
of DLC films....
Chapter 4
Table 4.1 Summary of various aspects of solution‐processed and PP depositio...
Chapter 6
Table 6.1 Selected high‐performance p‐type organic TE materials and their S...
Table 6.2 Selected high‐performance n‐type organic TE materials and their S...
Table 6.3 Selected high‐performance organometallic TE materials and their S...
Chapter 7
Table 7.1 Carbon‐enhanced inorganic piezoelectric materials.
Chapter 8
Table 8.1 Electrical, mechanical, and thermal properties of SWCNT and MWCNT...
List of Illustrations
Chapter 1
Figure 1.1 Multiforms of carbon‐based materials and their applications in co...
Figure 1.2 Number of published articles with the keywords “carbon” and “carb...
Chapter 2
Figure 2.1 Various carbon allotropes.
Figure 2.2 Approaches route for carbon‐based nanostructures fabrication.
Figure 2.3 Overview of the chemical interaction process involved in nanostru...
Figure 2.4 (a) Schematic of the CVD process used for graphene synthesis from...
Figure 2.5 Schematic of (a) thermal and (b) plasma‐enhanced CVD reactors....
Figure 2.6 Schematic of typical (a) cold‐wall and (b) hot‐wall CVD reactors....
Figure 2.7 Schematic of (a) ion bombardment process (b) ion irradiation expe...
Figure 2.8 Raman spectra of deposited DLC films using different hydrocarbon ...
Figure 2.9 The Raman spectra of the monolayer, bilayer, three layers, and fo...
Figure 2.10 Signals generated from electron‐beam‐irradiated sample.
Figure 2.11 (a) SAED and (b) EDX spectra corresponding to Ag‐CNF.
Figure 2.12 Spherical concentric‐shell carbon onion, generated under electro...
Figure 2.13 (a) Schematic diagram of the experimental setup for Ag‐CNF fabri...
Figure 2.14 (a–f) Time‐lapsed HRTEM images of Ag‐incorporated CNF during the...
Figure 2.15 High magnification images (a) before and (b) after the FE proces...
Figure 2.16 (a) Video clip showing the nano‐soldering process of CNTs with c...
Chapter 3
Figure 3.1 Variety of synthetic carbon allotropes with differently hybridize...
Figure 3.2 Schematic representation of C
60
. (a) Ball and stick model, (b) sp...
Figure 3.3 Atomic structure of single‐walled carbon nanotube. (a) Schematic ...
Figure 3.4 Schematic representations of (a) hydroxylfullerene, (b) carboxyfu...
Figure 3.5 Schematic representations of theoretical conjugation of proteins ...
Figure 3.6 Schematic representation of electrochemically driven anchoring of...
Figure 3.7 Schematic of the PECVD system.
Figure 3.8 Growth of N‐doped nanocrystalline graphene by plasma‐assisted che...
Figure 3.9 Low‐energy electron diffraction (LEED) patterns of (a) pristine g...
Figure 3.10 (a) Schematic representation of photoisomerization of DR1P on gr...
Figure 3.11 Graphene‐based piezoresistive pressure sensors. (a, b) Optical i...
Figure 3.12 Buckled graphene ribbon strain sensors. (a) Schematic representa...
Figure 3.13 Current–voltage characteristics of the fabricated pressure senso...
Figure 3.14 Raman spectra of pre‐plasma treated device (black curve) and the...
Figure 3.15 Fully passivated CNTFET‐based gas sensors. (a, b) SEM images of ...
Chapter 4
Figure 4.1 An experimental current–voltage (
I–V
) plot of a Pt–TiO
2−x
...
Figure 4.2 Cross‐sectional structures of the as‐fabricated (a) NVM device an...
Figure 4.3 Schematic diagram of the fabricated NVM device.
Figure 4.4 Schematic diagram of the fabricated tristable NVM device. The ins...
Figure 4.5 (a) Schematic diagram and SEM cross‐sectional image of the device...
Figure 4.6 (a) Schematic diagram and (b) SEM cross‐sectional structure of th...
Figure 4.7 (a–e) AFM images of the fabricated chemically converted graphene ...
Figure 4.8 AFM images of (a) first‐layer 100‐nm‐thick GO film on PEDOT:PSS/P...
Figure 4.9 (a) Schematic diagram of the spinning process for the formation o...
Figure 4.10 (a) Schematic drawing and TEM image of the proposed ITO/RGO/ITO ...
Figure 4.11 (a) ZnO–rGO memristor
I
–
V
curve, and (b) STPD behavior.
Figure 4.12 Fabrication and geometry of a paper RRAM. (a) Schematic diagram ...
Figure 4.13 Fabrication procedures for the n‐type flexible organic transisto...
Figure 4.14 (a) Photograph of the array of Ag/GO/ITO 25 devices. (b) Optical...
Figure 4.15 (a) Schematic diagram and the SEM cross‐sectional structure of t...
Chapter 5
Figure 5.1 Basic carbonous structures.
Figure 5.2 Schematic representation of DSSC working.
Figure 5.3 Schematic representation of different perovskite solar cell struc...
Chapter 6
Figure 6.1 Thermoelectric energy generator: (a) schematic illustrating charg...
Figure 6.2 Multi‐mission radioisotope thermoelectric generator (MMRTG) used ...
Figure 6.3 Seebeck effect causes an induced voltage in response to the appli...
Figure 6.4 Peltier effect causes cooling or heating in response to an applie...
Figure 6.5 Material properties of commercial p‐type bismuth telluride. (a) S...
Figure 6.6 Material properties of commercial n‐type bismuth telluride. (a) S...
Figure 6.7 Simplified one‐dimensional energy equilibrium model for TEG. (a) ...
Figure 6.8 Figure‐of‐merit,
zT
of (a) p‐type.
Figure 6.9 Some of the widely used TE materials with their operating tempera...
Figure 6.10 A wearable organic TE generator based on carbon nanotubes could ...
Figure 6.11 Schematic illustration of the integer charge transfer (CT) withi...
Figure 6.12 Thermoelectric properties of P3HT (which has a relatively shallo...
Figure 6.13 Schematic illustrating OTEG using a roll‐to‐roll printing proces...
Figure 6.14 Photographic images of electricity generation by the flexible PP...
Figure 6.15 Single‐couple OTEG printed on a glass substrate for power genera...
Figure 6.16 (a) Photograph and (b) output power and voltage versus current o...
Chapter 7
Figure 7.1 Schematic diagram of piezoelectric effect.
Figure 7.2 Carbon‐enhanced lead‐based piezoelectric ceramics. (a) Schematic ...
Figure 7.3 Mechanism of the enhancement with carbon materials. (a) Schematic...
Figure 7.4 Structure of (a) nonpolar
α
‐phase and (b) polar
β
‐phase...
Figure 7.5 (a) Schematic core–shell structure of interface modulated 0D piez...
Figure 7.6 (A) Schematic of the 3D‐printing system for the PVDF–TrFE nanobel...
Figure 7.7 Schematic of GAg‐induced self‐polarization among the PVDF chains ...
Figure 7.8 SEM images of the etched fracture surfaces of GQD/PVDF composite,...
Figure 7.9 Schematic for deposition of PVDF nanofibers around conductive cor...
Figure 7.10 (A) Schematic representation of electrospun fiber‐based hybrid n...
Figure 7.11 (A) Piezoelectric nanogenerator is attached to the rear wheel of...
Chapter 8
Figure 8.1 Structures of neat graphene (a) and GO different structures as pr...
Figure 8.2 Folding a graphene sheet accordingly with a chiral vector to lead...
Figure 8.3 Longitudinal section of (a) SWCNT and (b) MWCNT.
Figure 8.4 Mechanism of CNTs growth during CVD process: root and tip growth....
Figure 8.5 3D representation of (a) C
60
, also known as buckyball, and (b) fu...
Figure 8.6 Atomic force microscopy caption of a single FM image of an MWCNT....
Figure 8.7 Schematic nanotorsional actuator based on CNT.
Figure 8.8 Scheme of the actuators based on the ion‐transfer mechanism.
Figure 8.9 Actuation performances of graphene‐based Nafion actuator.
Figure 8.10 GO‐based membrane actuator.
Figure 8.11 Straightening‐back phenomena of neat Nafion (blue line) and full...
Chapter 9
Figure 9.1 Depiction of CDs (a) after surface oxidative treatment and (b) af...
Figure 9.2 Exciting CDs phosphors with ultraviolet and sunlight. (a) Images ...
Figure 9.3 CDs powders working in LEDs. (a) Images of CNRs dispersions and p...
Figure 9.4 Structures and EL spectra of LEDs employing CDs. (a) The device s...
Figure 9.5 CNT works as an emission material on display. (a) Schematic of tr...
Figure 9.6 CNTs as alignment material and polarizer in LCD. (a) Schematic of...
Figure 9.7 CNT–TFT application in LCD and OLED. (a) Schematic of LCD with CN...
Figure 9.8 CNT film as transparent electrode and touch panel of the display....
Figure 9.9 Graphene and graphene oxide as the liquid‐crystal materials of LC...
Figure 9.10 Graphene transparent electrode in the display. (a) Graphene film...
Guide
Cover Page
Table of Contents
Title Page
Copyright
Preface
Begin Reading
Index
Wiley End User License Agreement
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Enhanced Carbon‐Based Materials and Their Applications
Edited by Poh Choon Ooi, Mengying Xie, and Chang Fu Dee
Editors
Dr. Poh Choon Ooi
Institute of Microengineering and Nanoelectronics (IMEN)
Universiti Kebangsaan Malaysia
43600 Bangi, Selangor
Malaysia
Dr. Mengying Xie
State Key Laboratory of Precision Measuring Technology and Instrument
College of Precision Instruments and Opto‐electronics Engineering
Tianjin University
Tianjin, 300072
China
Dr. Chang Fu Dee
Institute of Microengineering and Nanoelectronics (IMEN)
Universiti Kebangsaan Malaysia
43600 Bangi, Selangor
Malaysia
Cover: © Andrey Suslov/Shutterstock
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Print ISBN: 978‐3‐527‐34802‐2
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Preface
Carbon has drawn the attention of global researchers because of its dimensional structural flexibility, which can be transformed into different materials according to sp, sp2, and sp3 hybridization. Moreover, its outstanding mechanical, electrical, thermal, optical, and chemical properties have been extensively employed in designing and developing from the conventional macro realm for structural, mechanical, and chemical reinforcement/strengthen applications, down to micro/nanodomain, primarily material doping, conductivity, and mobility modulation until all carbon electronics and integrated circuits. Their applications expand cross‐disciplinary into physics, chemistry, and biological subjects. Such diverse carbon material applications are not possible to be covered in a book or even in a book series. Therefore, we focus on specific frontier applications of carbon‐based smart electronic materials for certain latest advanced areas. This book is intended to provide information about the introduction to the latest development of carbon‐based materials, preparation methods, functionalization, and applications of carbon‐based nanomaterials. The discussion extends to the sensor, piezoelectric, thermoelectric, actuator, nonvolatile memory (NVM), optoelectronic, energy harvesting, and display applications.
This book begins with an overview of carbon‐based materials and their synthesis methods in Chapters 1–3. Chapter 1 comprises a cursory overview of this book, a brief introduction of carbon‐based materials and their applications, followed by the book outline. Chapter 2 discusses the recent development of carbon allotropes. The typical carbon‐based nanomaterial fabrication and characterization methods have been provided as well. Chapter 3 highlights the recent advances in chemically modified and functionalized low‐dimensional carbon‐based nanomaterials, especially fullerenes, carbon nanotubes, and graphene. The enhanced intrinsic properties of these functional nanomaterials in optoelectronics, strain–pressure, and gas‐sensing applications are also presented.
Advanced topics of enhanced carbon‐based materials and their applications are presented in Chapters 4–9. Chapter 4 delineates the discovery of memristor‐based memory, substrate options, and the effect of electrode materials. Then, an explicit discussion on solution‐processing techniques and plasma polymerization deposition utilized to construct the metal–insulator–metal structure of carbon‐based NVM devices will be presented. Chapter 5 reviews the developments in carbonous materials, including fullerene, carbon nanotubes, carbon black, graphene, and carbon quantum dots, with their wide applications in optoelectronics. Chapter 6 presents the working principle of thermoelectric energy harvesting, including materials, devices, and applications. This chapter primarily focuses on organic and hybrid materials, a promising solution for lightweight and conformal thermoelectric power generation. Chapter 7 describes carbon‐enhanced piezoelectric materials and demonstrates their applications as sustainable energy harvesters and biomechanical sensors. The introduction of carbon‐based nanomaterials into poly(vinylidene fluoride) and its copolymer matrix to enhance their performance as energy harvesters will be emphasized. Chapter 8 provides an overview and discussion of actuators based on carbon nanostructures, particularly carbon nanotubes, graphene, graphene oxide, and fullerene. Subsequently, the factors that allow carbon materials to be one of the most promising actuator resources will be discussed. Chapter 9 elaborates on the display performance enhancement of carbon nanomaterials, especially carbon dots, carbon nanotubes, and graphene/graphene oxide. The remaining challenges and further improvement aspects are also proposed for future optimization and commercialization of carbon‐based displays. Finally, Chapter 10 summarizes the overview of this book and the future prospects and challenges of enhanced carbon‐based nanomaterials to be overcome before the large‐scale production of carbon‐based products.
In a nutshell, we hope that the broad spectrum of readers, particularly the scientific and industrial community, will find this book helpful to gain valuable experience and references related to enhanced carbon‐based materials and their applications.
18 April 2022
Poh Choon Ooi
Institute of Microengineering and Nanoelectronics (IMEN)
Universiti Kebangsaan Malaysia
43600 Bangi
Selangor
Malaysia
Mengying Xie
State Key Laboratory of Precision Measuring Technology and Instrument
College of Precision Instruments and Opto‐electronics Engineering
Tianjin University
Tianjin 300072
China
Chang Fu Dee
Institute of Microengineering and Nanoelectronics (IMEN)
Universiti Kebangsaan Malaysia
43600 Bangi
Selangor
Malaysia
1Enhanced Carbon‐Based Materials and Their Applications
Poh Choon Ooi1, Mengying Xie2, and Chang Fu Dee1
1Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
2State Key Laboratory of Precision Measuring Technology and Instrument, College of Precision Instruments and Opto‐electronics Engineering, Tianjin University, Tianjin, 300072, China
1.1 Overview
This book entitled “Enhanced Carbon‐Based Materials and Their Applications” intends to deliver the synthesis methods and role of carbon‐based materials that can be introduced into the device to enhance the performance of several types of electronic devices. The theme of this book is multidisciplinary and provides the broader scientific and industrial community with a timely and carefully referenced overview that provides a summary of carbon‐based materials and applications. The book has been written in style to make it accessible for academics to provide an overview of synthesis methods and characterization techniques of carbon nanomaterials. On the other hand, this book also demonstrates the various reported applications for carbon‐based and enhanced materials for professionals.
1.2 Glance of Carbon‐Based Materials
Carbon is the 4th most abundant element in the universe and the foundation of life, despite the various elements on the Earth. Its existence extended from nonliving substances to living objects. All organic substances that are found in nature consist of carbon. It has unique physical and chemical properties in multiple forms [1]. The carbon material is a big family with many allotropes, and they possess unique structure, texture, and properties. These carbon materials are classified according to their C‐to‐C bonding, namely, sp, sp2, and sp3 hybrid orbitals of carbon atoms. Carbon structures include three primary allotropes known as diamond, graphite, and fullerene. Diamond and graphite are the natural carbon sources that humankind could discover abundantly on Earth [1].
Diamond shows sp3 hybrid orbitals, consisting of a tetrahedron network of carbon atoms. It can be naturally formed under prolonged high pressure and high temperature. In the sp3 hybridized form, the C atom and adjacent C atom are linked up by covalent bonds. Consequently, it leads to a strong bonding and tetrahedral atomic arrangement that allows the diamond to be the hardest substrate among others. Diamond is a colorless transparent substrate, which is heavy and extremely hard. It does not conduct electricity but has high thermal conductivity and melting point. In addition, diamond has high resistance to chemical corrosion. For more than one century, this special allotrope of carbon has only been used as a precious stone in making jewelry, ornaments, and glass cutters. Nonetheless, recent scientific development has extended its application into medical science, material science, semiconductor, and nanotechnology [2–6].
Graphite shows sp2 orbitals. It is a greyish‐black opaque substance with a high‐melting point and low coefficient of thermal expansion. In addition, graphite also has high thermal, electrical conductivity, chemical, and corrosion resistance. These properties enable wide applications from pencil lead, high‐temperature lubricant, paint, printing, plastic industry, and electrode in battery/cell up to the application as nuclear reactor moderator [7, 8]. A fullerene is the third allotropes of carbon whose molecule consists of carbon atoms connected by covalent bonds to form fused rings of five to seven. Fullerenes are polyhedral carbon cages in which sp2‐carbons are directly bonded to three neighbors in an arrangement of five‐ and six‐membered rings [9]. Fullerene (also called “buckyball”) can be constructed by 24, 28, 32, 36, 50, 60, 70, 72, etc., number of carbon atoms. Compared to other types of carbon allotrope, it can be dissolved in common solvents, for example, carbon disulfide and toluene, at room temperature. Recent research on fullerene has enabled its applications in catalysis, water purification, antiviral and antioxidant activities, biohazard protection, magnetic resonance imaging (MRI) medium for diagnostic agents, and the latest nanotechnology advancement in drug and gene delivery [9–14].
Graphite, carbon fiber, etc., have been widely used in the manufacturing and industrial field. Modern applications for carbon materials are focused on the nanostructured form of carbon elements. The world demand for the carbon nanomaterials market is expected to reach US$ 21.97 Billion in 2026. A compound annual growth rate (CAGR) of 4.1% was predicted during this forecast period [15]. The end‐use area in industries includes aviation, energy, electrical and electronics, medical and healthcare, packaging and backend, transportation, automotive, and consumer goods. Its nontoxic and biocompatible characteristics have greatly enhanced the possibility of its applications to areas from nonliving to living things. Figure 1.1 summarizes the allotropes/form/type of carbon in a concentric circle. Carbon‐based materials can be categorized into different types, which are carbon nanotubes (CNTs), layered sheets (graphene/graphite), carbon black, fullerene, and quantum dots.
Most carbon‐based materials are naturally stiff, lightweight, and highly conductive [16, 17]. In addition, they can be easily engineered to achieve targeted material properties. For example, CNTs have been assembled into fibers with ultrahigh specific strength and stiffness, which are much higher than commercially available engineering fibers [17]. These lightweight, stiff CNT fibers show their potential in many structural applications, such as the construction of energy‐efficient airplanes and space structures. Although single‐crystal graphene shows excellent properties, single crystals need to be assembled into the macroscopic structure in many practical applications. A single piece of graphene is delicate, but linking them through chemical or physical approaches can form a stronger 3D network [18, 19]. It has been reported that porous structured 3D graphene assembly can be even lighter than air and ten times as strong as mild steel [19]. In addition to the inherent properties of carbon nanomaterials, the high surface area and large pore volume of the 3D porous structure can create more space for the transportation or storage of the electron/ion, gas, and liquid, which enables remarkable sensitivity for sensors, large capacity for supercapacitors, and high‐power density batteries [20].
Figure 1.1 Multiforms of carbon‐based materials and their applications in contemporary electronic and optical‐related technologies.
On the other hand, carbon‐based materials always face irreversible aggregation and insolubilization issues when preparing aqueous suspensions due to their van der Waals attractions between single crystals and hydrophobicity. Stable and distributed aqueous or organic suspensions are the key factors to enable repeatability and homogeneity, which directly limit their industrial applications. Several functionalization approaches have been utilized to treat carbon‐based materials to reduce aggregation and insolubilization [21]. The commonly used method modifier to achieve stabilized aqueous or organic dispersions is an amphiphilic or covalent surfactant. For instance, graphene nanosheet was stably dispersed in water, N,N‐dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) by covalently functionalized polydisperse graphene with amine‐terminated ionic liquid [22]. Amphiphilic surfactant poly(sodium 4‐styrenesulfonate) (PSS) has been coated on graphitic nanoplatelets to provide stable aqueous dispersion with the aid of ultrasonic treatment. Reduced graphene was stabilized via association with the hydrophobic backbone of PSS, while the hydrophilic sulfonate side groups sustained the graphene‐PSS in water [23].
1.3 Applications
In this book, we infer “enhanced carbon‐based materials” as modified properties of pristine carbon materials derivatives that can be used to enhance the performance of devices. In the examples mentioned above, the formed functional variants in enhanced carbon‐based nanomaterials play a crucial role in distinguishing specific applications. Plenty of methods can be used to enhance the carbon materials, and the resulting enhanced carbon‐based materials can be categorized as (i) doping, (ii) alloying, and (iii) surface attaching of alien atoms/molecules in order to alter their physical and chemical properties. Those three methods mentioned above achieve the same goal in the nanoscale material form, resulting in surface energy/chemistry change. This is due to its high surface‐to‐volume ratio of nano‐regime properties. The change in the surface energy enhances a better coupling for signal transduction used for different applications with the attachment of dedicated alien substances, especially luminescent molecules/substances for biomarkers, chemical/protein‐based drugs/genomic elements for medical applications, moieties for catalysis or plasmonics, and polar/nonpolar materials for modulation on wettability [24–30]. Again, those attachments in different forms enhance the carbon materials and enable the multiple functions used for various applications.
In the trend toward miniaturization, electronics require small, flexible, lightweight, and multifunction devices. These demands have driven the rapid development of nanotechnology. Enhanced carbon‐based materials have become the most desirable materials for future electronics. They have driven the development of revolutionary technologies, such as advanced materials, renewable energy, biomedical, and smart electronic devices, due to their superior mechanical and electrical performances. These applications associated with enhanced carbon‐based materials have shown low‐power consumption, high sensitivity, selectivity, and efficiency. Figure 1.2 shows that the research on carbon‐based materials has increased by leaps and bounds in the recent three decades since 1980 [31]. Over the past three decades, the number of published articles with the keywords “carbon” and “carbonuous” has increased tremendously, more than 12 times from 10 690 in 1980 to 137 176 in 2021. Carbon‐based materials have shown great versatility since they can be easily functionalized physically and chemically modified with other elements. The excellent and tunable mechanical, electrical, thermal, optical, and chemical properties of carbon‐based nanomaterials are desired to be included in electronic gadgets to improve overall performance further [32].
Figure 1.2 Number of published articles with the keywords “carbon” and “carbonuous” from 1980 to 2021.
1.4 Outline of This Book
The book consists of 10 chapters to provide a brief overview of state‐of‐the‐art carbon‐based and enhanced nanostructures and their applications. Chapter 2 outlines the fundamental insight into carbon‐based materials synthesis and material characterization techniques. Chapter 3 presents the advanced functionalization techniques of carbon‐based materials and their applications, such as carbon‐based sensors that consist of planar graphene and graphene hybridized material. Their specific material properties, preparation methods, and sensing behaviors are discussed. The following chapters (Chapters 4–9) focus on the overview of carbon‐enhanced materials. The integration of these materials is of great importance for the performance enhancement of various future electronics applications, including nonvolatile memories, optoelectronic devices, thermoelectrics, energy harvesters, actuator, and display. In addition, an overview of this book will be summarized in the conclusions, and future directions for the applications of carbon‐based and enhanced materials are discussed.
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115 (15): 7046–7117.
2
Krüger, A., Liang, Y., Jarre, G., and Stegk, J. (2006). Surface functionalisation of detonation diamond suitable for biological applications.
Journal of Materials Chemistry
16 (24): 2322–2328.
3
Ando, T. et al. (1996). Direct interaction of elemental fluorine with diamond surfaces.
Diamond and Related Materials
5 (9): 1021–1025.
4
Hui, Y.Y., Cheng, C.‐L., and Chang, H.‐C. (2010). Nanodiamonds for optical bioimaging.
Journal of Physics D: Applied Physics
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2Carbon‐Based Nanomaterials: Synthesis and Characterizations
Yazid Yaakob1 and Shahira L. Kamis2
1Universiti Putra Malaysia, Department of Physics, Faculty of Science, 43400, Selangor, Malaysia
2Universiti Teknologi Malaysia, Malaysia‐Japan International Institute of Technology (MJIIT), Tribology and Precision Machining (TriPrem) i‐Kohza, Department of Mechanical Precision Engineering, 54100, Kuala Lumpur, Malaysia
2.1 Introduction
This era shows rapid progress of technology, especially in electronic fields, along with fast‐driven developments of information technology toward industrial revolution 4.0. This trend has been escalated with recent pandemic crisis that urged people around the globe to practice social distance and to adapt “new norms,” such as practicing social distance, utilizing contactless gadgets and promoting “work from home” [1]. The rapid advancement now even reached the stage to achieve and control the structural and functional part of a very small component down to the microlevel. These comply with Moore's law, where he predicts that the miniaturization of semiconductor devices (number of transistors per chip) should be doubled every two years [2]. To realize this possibility, the researcher has diligently realigned their research direction toward product integration for high‐density, high‐speed, high strength‐to‐weight ratio, and low‐energy‐consumption devices, but at the same time require low production cost. Nanotechnology, the idea first introduced by Richard P. Feynman in 1959, is the most promising research field that offers the opportunity to exploit novel properties of materials at the nanoscale (10−9 m) level, attracting many investors as well as general public attention until now. Among them, carbon nanostructures (CNSs) are the most trending materials within the field of nanoscience and technology owing to their unique properties (high mechanical strength, high electrical and thermal conductivity, excellent optical properties, chemical inertness, and versatility). These superb features have been exploited to develop numerous electronic devices, sensors, batteries, and composites to be employed in the majority of scientific areas.
2.1.1 Carbon
Carbon is one of the most abundant elements ever known and a major constituent element of all living things, as all organic compounds are comprised of carbon networks. As an element or compound, carbon has been utilized in human civilization and daily life for long centuries. Ever since ancient times, carbon‐based materials, such as coal and charcoal, have been used as energy resources. Carbon black and graphite have also been adopted as writing tools. As time progresses, the use of carbon has been creatively manipulated by blending them into other matrix composites to produce enhanced properties of composite materials. For example, “wootz steel” as raw materials to forge Damascus blades that exhibited extraordinary mechanical properties is actually incorporated with carbon nanotubes, which scientists later revealed in the modern day [3]. Graphite and diamonds were recognized during eighteenth century as two existing natural crystalline allotropic forms of carbon structure, yet they exhibit totally different appearances, crystal structures, and properties [4]. Since then, the rapid development of carbon‐based materials has taken part in the industrial revolution. As a case in point, the sp2‐hybridized graphite is important as raw material for the lead of a pencil, vehicles brake lining, and circuit electrodes, and is further utilized in carbon fiber for sports equipment and aeronautic applications due to their excellent mechanical properties. Diamonds, the sp3‐hybridized carbons that possess a sparkle‐shiny appearance known as the hardest natural materials to date, have been utilized as jewelry and cutting tools.
2.1.2 Allotropes of Carbon
The development of carbon‐based nanotechnology has been driven by the refinement of microscopy that opens the path of discovery at the nanoscale. CNS has been identified to consist of a variant of low‐dimension allotropes due to its valency, as shown in Figure 2.1[6]. It was started with the discovery of fullerene in 1985, which triggered the exploration of a new class of low‐dimension materials. Then followed by the first observation reports of CNTs in 1991, and later the scotch tape exfoliation of graphene in 2004 [7, 8]. This surprising finding, which is recognized as miracle materials of the century (awarded Nobel Prize in 2010), has triggered even more exploration of other thermodynamically stable two‐dimensional (2D) materials (hexagonal boron nitride, molybdenum disulfide, MXenes, etc.). Even though these stories have passed over decades, the exploration of their potential still shows no limit and continues to be a hot topic among researchers and industry players. A brief survey on the Web of Science database for the last five years (2016–2020) with the keywords of the famous “Carbon nanotube” and “Graphene” displayed more than 73 628 and 146 375 articles published, respectively. This outcome indicates that graphene still received more attention than carbon nanotubes and any other carbon allotropes in the scientific community.
Graphene has a fundamental building block of 2D honeycomb lattice, which can be considered the “mother” of other sp2‐hybridized building blocks of CNS. This super carbon is already famous for its first‐rate electrical, optical, mechanical, thermal, and chemical properties, making it very flexible to be functionalized and potentially applied in various devices [5]. They even are considered a suitable replacement candidate in semiconductor devices post‐silicon. Other than these graphitic (sp2)‐dominated forms of CNS, other forms and hybridization, such as amorphous carbon and diamond structure, also exhibit their unique properties. Table 2.1 summarizes some of the CNS's unique properties, which vary depending on their structure forms. For example, three‐dimensional diamonds possess high thermal conductivity and inelastic behavior, while zero‐dimensional nanodiamonds consisting of sp2/sp3 hybridization behave more elastic and have lower thermal conductivity [9–12]. Other than basic forms mentioned above, there is also a lot of functionalized and hybrid forms to join the carbon class families, such as carbon dots, graphene quantum dots, graphene oxide, diamond‐like carbon and diaphite [14], which have been produced to fill the gap of technology‐driven opportunities.
Figure 2.1 Various carbon allotropes.
Source: Reproduced from Savage [5] with the permission of American Chemical Society.
As summarized in Table 2.1, crystalline carbon in different forms and dimensions exhibit contrasting physical and chemical properties. Various physical phenomena and structure‐related properties have been explored or discovered. At the same time, the most established CNTs and graphene can be ideal forms of materials to understand the various other forms. Even though specific applications have already made use of CNS, a bunch of fundamental questions still need to be answered before it can totally replace the existing materials and encourage further innovation of new class carbon‐related materials. To give some insight on the topic, this chapter aims to provide an overview of the recent development of facile and economical synthesis methods of CNS and their typical characterization techniques. Finally, the potential for detailed characterization of CNS via in situ transmission electron microscopy will be introduced and summarized.
Table 2.1 Summary of some variation of carbon nanostructures properties.
Source: Adapted from Raccichini et al. [13].
Carbon nanostructure material
Dimensions
Hybridization
Hardness
Tenacity
Specific surface area (m
2
g
−1
)
Thermal conductivity (W m
−1
K
−1
)
Electrical conductivity (S cm
−1
)
Graphite
3
sp
2
High
Flexible, nonelastic
∼10–20
Anisotropic: 1500–2000, 5–10
Anisotropic: 2–3 × 10
4
Graphene
2
sp
2
Upper most (for single layer)
Flexible, elastic
∼1500
4840–5300
∼2000
CNTs
1
Mostly sp
2
High
Flexible, elastic
∼1300
3500
Structure‐dependent
Nanodiamonds [
9
,
10
]
0
sp
2
/sp
3
Mostly sp
3
Very high
Elastic
[11]
∼300–400
∼0.3–10
[12]
∼10
−11
depending on the presence of defects, impurities or dopants
Fullerene
0
Mostly sp
2
High
Elastic
80–90
0.4
10
−10
2.2 Synthesis of Carbon‐Based Nanostructures
At the moment, a lot of methods have been developed to synthesize CNS, whether by top‐down method or bottom‐up method, as illustrated in Figure 2.2[15]. Both paths have their role, as the top‐down approach offers size reduction of existing devices, which is beneficial for architectural structures in connecting macroscopic components. In contrast, the bottom‐up methods can build complex devices through strategic atomic arrangement, suitable for nanoscale short‐range order of product. These make a perfect combination to produce excellent integration devices based on nanofabrication [16]. CNS fabrication methods have been developed in various ways, either by physical or chemical processes. The common established synthesis methods are exfoliation (physical or chemical), pulsed laser deposition, arc discharge, ion/electron beam irradiation, and physical/chemical vapor deposition. However, most research directions have been moved toward a green and sustainable environment, so low cost, less complexity, and bio/eco‐friendly production have become popular. Recently, researchers from Rice University demonstrated a flash Joule heating technique to synthesize turbostratic graphene from plastic waste, which proved to have outstanding properties as filler in polyvinyl alcohol, cement, and concrete composites [17]. Researchers keep coming out with new CNS fabrication techniques and innovations to fulfill industries' desire for efficient and sustainable production. This section will focus on two types of techniques that are considered facile and economical fabrication, namely, chemical vapor deposition and ion irradiation.
Figure 2.2 Approaches route for carbon‐based nanostructures fabrication.
Source: Adapted from Habiba et al. [15].
2.2.1 Chemical Vapor Deposition Technique
The chemical vapor deposition (CVD) method was developed for carbon nanomaterials production in the 1960 and 1970s [18, 19]. High quality and high performance solid coating can be achieved using this method, with great potential for producing large‐area deposition. In contrast with other techniques for the growth of carbon nanomaterials, such as discharge using electric arc, chemical or plasma exfoliation, laser ablation, and sputtering, CVD is the most promising technology for producing a high‐growth rate, high morphological purity of the grown material. The carbon nanomaterials' synthesis via CVD is achieved through chemical reactions by placing carbon sources into a reactor. Thin films are formed on a heated substrate using thermal or electrical energy sources, such as inductive heating or plasma. Deposition parameters, such as the type of carbon source, catalyst, carrier gas, reaction chamber pressure, and substrate temperature, play a major role in producing thin films composed of carbon nanostructure.
Methane (CH4), ethane (C2H6), ethylene (C2H4), and acetylene (C2H2) are important carbon precursors for the growth of thin film produced by the CVD method [20]. The concentration and purity of carbon source gas can affect the formation of morphology and growth kinetics of thin films [21, 22]. However, these precursors are nonrenewable sources of carbon that originated from fossil fuels. These precursors are also known as inflammable carbonaceous gases, which require safety control and handling precautions. Alternatively, renewable energy sources and nonexplosive carbon sources, especially natural carbon sources and waste materials, are used to reduce fossil fuel dependency and cost. The summary for the use of carbon precursors in the synthesis of the thin films composed of carbon nanomaterials via the CVD method is listed in Table 2.2. A carrier gas, such as hydrogen, nitrogen, or argon, is usually employed to dilute the precursor molecules for chemical reactions.
Table 2.2 Precursor for the synthesis of carbon nanomaterials from different classes of hydrocarbon.
Carbon nanostructure
Hydrocarbon source
Temperature (°C)
References
Fossil based
CNFs
Ethylene (C
2
H
4
)
700
[23]
CNTs
Ethylene(C
2
H
4
), Acetylene(C
2
H
2
)
925
[24]
Graphene
Methane (CH
4
)
1060
[25]
DLC
Acetylene(C
2
H
2
)
300
[26]
Natural sources
CNTs
Camphor
700, 800, and 900
[27]
MWNTs
Jatropha curcas
450–850
[28]
Graphene
Palm oil
900 and 1000
[29]
Waste materials
CNTs
Natural rubber glove
600 and 700
[30]
CNTs
Waste latex
700
[31]
Graphene
Cooking palm oil
850–1100
[32]
Graphene
Fruit cover plastic waste and oil palm fiber
1020
[33]
Graphene
Solid plastic waste
1020
[34]
Graphene
Chicken fat oil
1080
[35]
For efficient carbon nanomaterial production, catalyst particles were introduced into the deposition system. Catalyst plays a key role in the improved quality and controls the size and shape of the carbon nanomaterials produced. Catalysts act as the nucleation site for decomposing the molecules induced carbon deposition on the substrate during the CVD process. Catalysts accelerate reactions by providing the surface area for the adsorption of carbon [36]. Transition metals, such as Cu, Ni, and Pt, are often used as a catalyst to obtain crystalline structure and improve the growth rate of synthesized materials [32, 37, 38].
The nanostructured thin films have a thickness range of a few 100 nm up to a few μm. The CVD of thin films is the result of complicated chemical reactions involving many intermediate steps. As illustrated in Figure 2.3, there are important chemical reactions involved in film growth in CVD, which can be summarized as follows [39]: (a) transport of reactants precursor molecules via gas diffusion at boundary layer region, (b) adsorption and surface diffusion of atoms on that surface, (c) chemical reactions on the substrate, (d) desorption of adsorbed species, and (e) diffusion out of gaseous reaction products through the boundary layer. The boundary layer results from fluid dynamics, which occur when the thin layer of a flowing gas tends to cling to the substrate surface. In this region, the gas stream velocity, concentration of the vapor species, and temperature are not equal to the same parameters in the main gas stream. Therefore, the growth rate of synthesized carbon nanomaterials is generally depending on a wide range of parameters, such as substrate temperature [40], operating pressure [41], carbon precursor/carrier gas ratio [42], and carbon solubility in transition metal catalysts [43].
Figure 2.3 Overview of the chemical interaction process involved in nanostructured thin‐film synthesized by CVD.
Source: Reproduced from Shang et al. [39] with the permission of Elsevier.
One of the facile CVD techniques is alcoholic catalytic chemical vapor deposition (ACCVD), which is operated up to ∼1100 °C to produce CNS using an alcoholic precursor. This method is very simple and flexible in varying CNS growth parameters to fit our resources. They can be operated at atmospheric or low‐pressure conditions with a creative heating method (double furnace, spray pyrolysis, heating mantle, etc.) to expand their potential in utilizing various precursor types: solid, liquid, and gas [44]. Figure 2.4 shows an example of a typical CVD procedure to synthesize graphene from solid waste plastic using the double‐furnace method.
Figure 2.4 (a) Schematic of the CVD process used for graphene synthesis from solid waste plastic. (b) Photograph of waste plastic used in these experiments. (c) Heating, annealing, growth duration, and cooling rate (∼16 °C min−2) for the graphene growth process.
Source: (a, c) Reproduced from Sharma et al. [34] with the permission of Elsevier, (b) Sharma et al. [34], Reproduced with permission from Elsevier.
Today, various kinds of enhanced CVD processes are also available that can be employed to synthesize CNS, which involve the use of plasmas, ions, photons, lasers, hot filaments, or combustion reactions to increase deposition rates and/or lower deposition temperatures. This method can be categorized based on a heating method, which is discussed in the next subtopic. Out of these techniques, thermal and plasma‐enhanced CVD are the two most dominant thin‐film deposition methods. Figure 2.5 shows a schematic of thermal and plasma‐enhanced CVD reactors.
2.2.1.1 Thermal Chemical Vapor Deposition
Thermal CVD uses higher temperatures (typically between 800 and 2000 °C) to heat hydrocarbon precursors and encourage the chemical reaction in a gas phase that results in thin films grown on the substrate. In 1966, the first thermal CVD on metals was reported to grow highly crystalline graphite films on Ni substrates [18]. Heating processes, such as hot plate heating, resistive heating, induction heating, and radiant heating, are usually used to reach a high temperature. The heat can be delivered externally (hot‐wall reactor) or internally (cold‐wall reactor). In hot‐wall reactors, the whole chamber is heated by an array of heat sources, such as halogen heater or quartz lamps, and the substrate is heated by radiation. In contrast, the substrate is heated by plate‐type heaters in cold‐wall reactors and the reactor walls are kept cold. Figure 2.6 shows a schematic of typical (a) cold‐wall and (b) hot‐wall CVD reactors. Besides, research works involving using thermal CVD to synthesize the carbon nanomaterials thin film are summarized in Table 2.3.
Figure 2.5 Schematic of (a) thermal and (b) plasma‐enhanced CVD reactors.
Source: Reproduced from Pessoa et al. [45] with the permission of Elsevier.
Figure 2.6 Schematic of typical (a) cold‐wall and (b) hot‐wall CVD reactors.
Source: Reproduced from Kim et al. [46] with the permission of Elsevier.
Generally, it is desirable to use low‐temperature and low‐pressure processes in CVD heating systems, which offer significant potential advantages to reduce unwanted gas‐phase reactions and enhance the thin‐film thickness uniformity. In this respect, the use of low‐pressure thermal CVD under 100 Pa with low dissociative temperatures of 800–900 °C has proven capable of producing CNTs by using C2H4 as carbon precursor [43]. The researchers also proposed using other hydrocarbon precursors, especially C2H2, as it is easier to decompose at lower temperatures. When using solid or liquid carbon precursors, double thermal CVD is needed, which has two independent heating zones; the first furnace for the precursor furnace and the second furnace for the deposition furnace where the substrate was placed [53].
2.2.1.2 Plasma‐Enhanced Chemical Vapor Deposition
Plasma‐enhanced CVD (PECVD) is different from other CVD methods in which the chemical reactions on the surface occur after the reacting gases create the plasma. In the PECVD process, a high‐frequency voltage is required to ignite plasma by liberating electrons from precursor molecules and atoms for creating thin films. Plasma can ionize and decompose the reactive gas, activate the chemical reaction, and create heat. As a result, the plasma could reduce the deposition temperature (approximately around 200–400 °C) and improve deposition rates. This technique also has the advantage of reducing operating costs involving energy to heat the gas phase and can use for materials and substrates, especially those that are not suitable for higher deposition temperatures. Although PECVD is known as a promising method, the quality of the deposited thin film can be affected by energetic particles (e.g. fast ions and electrons) from the plasma‐surface interaction, leading to increased surface defect densities.
Table 2.3 Summary of the related works used thermal CVD for synthesis of carbon nanomaterials thin film.
Carbon nanostructure material
Carbon precursor
Catalyst
Substrates
Carrier gas and flow rate
Deposition temperature (°C)
Cold‐wall reactor
Graphene
[25]
Methane (CH
4
)
—
Cu foil
Hydrogen (20 sccm) and argon (900 sccm)
1060
SWCNTs
[47]
Methane (CH
4
)
Al and Fe
Silicon
Hydrogen (20 sccm)
700–950
SWCNTs and MWCNTs
[48]
Ethanol
Co and Mo
Porous alumina
Hydrogen and argon
a)
650 and 830
Hot‐wall reactor
SWCNTs
[49]
Acetylene(C
2
H
2
), Methane (CH
4
)
Ni, Co, and Fe
Thermal Si‐oxide
—
600–950
MWCNTs
[50]
Methane (CH
4
)
Pt–W with MgO
–
Argon (200–500 sccm)
800
Graphene
[51]
Methane (CH
4
)
Co and Fe
Silicon
Hydrogen (50 sccm) and argon (300 sccm)
800
Hybrid cold‐ and hot‐wall reaction chamber
Graphene
[52]
Methane (CH
4
)
–
Cu foil
Hydrogen (20 sccm)
1035
a) Flow rates are not mentioned.
The PECVD method can be categorized in different deposition processes depending on the power source that generates plasma. Various types of plasma can be artificially generated by using electric power sources at various plasma excitation frequencies, which could be further divided into three subcategories; audio frequency (10 or 20 kHz), radio frequency (13.56 MHz), and microwave frequency (2.45 GHz) [54]. Among them, radio frequency (RF)‐PECVD and microwave (MW)‐PECVD are widely used plasma sources for carbon nanostructure thin‐film deposition.
According to Wang and Moore [55], CNTs could grow wells by RF‐PECVD because there is a higher density of reactive radicals than in dc‐PECVD at the same deposition condition. This indicates that RF‐PECVD is capable of synthesizing CNT at low temperatures (∼180 °C). In another study, it has already been reported that 13.56 MHz of RF‐PECVD is capable of growing multilayer graphene on Ni and Co films at a relatively low temperature of 600 °C with 40 W plasma power [56]. In 2011, Qi et al. reported that the thickness of graphene (corresponds to a few graphene layers) prepared by RF‐PECVD could be controlled by the ratio of CH4 flow rate in a mixture of reaction gases [57]. Also, RF‐PECVD is one of the most popular techniques for the deposition of DLC films because it can improve the quality of the film by producing uniform thickness over a large area.
To date, MW‐PECVD has been used extensively to achieve high‐deposition rates and/or high fragmentation of precursor material for thin‐film deposition. The MW‐PECVD process involves applying high electromagnetic radiation (in the GHz range) to generate plasma in the reaction chamber. The plasma is physically transformed into nanoparticles after being heated, diffused, and condensed to a substrate film. For example, Fernandes et al. employed a 2.45 GHz MW‐PECVD to obtain growth of the NCD/CNT hybrid films on Si substrate using a CH4/H2 mixture with Fe catalysts under 700 °C [58]. Another study by Chockalingam et al. successfully synthesized MWCNT graphene‐like nanocarbon hybrid film using CH4/H2 mixture under 600 °C [59]. This hybrid film has the potential to enhance electrical properties by using graphene as connecting particles within the porous CNT network. Cho et al. provided a comparison study between different deposition conditions used in synthesized DLC films; RF‐PECVD and MW‐PECVD [60]. It was found that both deposition methods produce similar DLC structures, but there are differences in surface roughness and coating thickness.
Recently, there has been an improvement in the CVD method, such as introducing pulsed plasma discharge, in order to reduce the occurrence of gas‐phase polymerization caused by continuous‐wave discharge [61]. The high‐power pulses significantly produced higher plasma density and deposition rates compared to traditional PECVD. In 2018, Mamun et al. proposed that the pulsed dc PECVD system can be considered an alternative to the conventional RF PECVD. It improved film properties and reduced energy consumption to promote the growth of DLC film [26].
2.2.2 Ion Irradiation Technique
The irradiation method was developed by utilizing an ion or electron beam to sputter the deposition of samples in the targeted substrate. Normally, the ion/electron beam is known to be destructive and introduces defects toward the target materials' surface. However, these phenomena also will introduce structural change and enhancement of properties of the nanomaterials [62], which lead to a creative and easy way to modify them. For example, Banhart reported that structural transformation of graphitic particles into crystalline diamond occurs when exposed to intense electron beam irradiation of about 10–200 A cm−2 current density in transmission electron microscopy (TEM), as shown in Figure 2.12[63].
Generally, during the ion irradiation process, the bombardment exposure will erode the solid material surface. The erosion rates are characterized by sputtering yield, defined as the mean number of emitted atoms per incident particle, depending on materials. As illustrated in Figure 2.7
