Handbook of Graphene, Volume 5 E-Book
233,99 €
Mehr erfahren.
- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
The fifth volume in a series of handbooks on graphene research and applications Graphene is a valuable nanomaterial used in technology. The Handbook of Graphene: Graphene in Energy, Healthcare, and Environmental Applications is the fifth volume in the handbook series. The book's topics include: graphene nanomaterials in energy and environment applications and graphene used as nanolubricant. Within the handbook, three-dimensional graphene materials are discussed, as are synthesis and applications in electrocatalysts and electrochemical sensors. The battery topics cover: graphene and graphene-based hybrid composites for advanced rechargeable battery electrodes; graphene-based materials for advanced lithium-ion batteries; graphene-based materials for supercapacitors and conductive additives of lithium ion batteries. The book's graphene-based sensor information addresses flexible actuators, sensors, and supercapacitors.
Sie lesen das E-Book in den Legimi-Apps auf:
Seitenzahl: 1275
Veröffentlichungsjahr: 2019
Ähnliche
Contents
Cover
Preface
Chapter 1: Graphene Nanomaterials in Energy and Environment Applications
1.1 Introduction
1.2 Preparations of Graphene-Based Materials
1.3 Applications of Graphene-Based Materials in Energy and Environment
1.4 Conclusion and Outlook
Acknowledgments
References
Chapter 2: Graphene as Nanolubricant for Machining
2.1 Introduction
2.2 Tribological Testing of Graphene Nanolubricants
2.3 Machining Using Graphene as Nanolubricant
2.4 Conclusion and Outlook
References
Chapter 3: Three-Dimensional Graphene Foams for Energy Storage Applications
3.1 Introduction
3.2 Fabrication, Structure, and Performance of GF
3.3 Applications of GF in Energy Storage Devices
3.4 Conclusions and Outlook
References
Chapter 4: Three-Dimensional Graphene Materials: Synthesis and Applications in Electrocatalysts and Electrochemical Sensors
4.1 Introduction
4.2 Synthesis of 3D Graphene-Based Materials
4.3 Electrocatalytic Activity of 3D Graphene-Based Materials
4.4 Electrochemical Sensing Properties of 3D Graphene-Based Materials
4.5 Conclusion
Acknowledgments
References
Chapter 5: Graphene and Graphene-Based Hybrid Composites for Advanced Rechargeable Battery Electrodes
5.1 Introduction
5.2 Li-Ion Batteries
5.3 Na-Ion Batteries
5.4 Li–S Batteries
5.5 Li–Air Batteries
5.6 Summary and Perspectives
References
Chapter 6: Graphene-Based Materials for Advanced Lithium-Ion Batteries
6.1 Introduction of Lithium-Ion Batteries
6.2 Graphene and Its Properties
6.3 Synthesis Methods of Graphene for LIBs
6.4 Graphene-Based Composites for LIBs
6.5 Graphene-Based Composites for Li–S Batteries
6.6 Graphene-Based Composites for Li–O
2
Batteries
6.7 Conclusions and Outlook
References
Chapter 7: Graphene-Based Materials for Supercapacitors and Conductive Additives of Lithium Ion Batteries
7.1 Introduction
7.2 Experimental Technique
7.3 Graphene and Carbon Nanotube Composite Materials
7.4 Graphene and Nanostructured MnO
2
Composite Electrode
7.5 Polyaniline Nanocone-Coated Graphene and Carbon Nanotube Composite Electrode
7.6 Electrodeposition of Nanoporous Cobalt Hydroxide on Graphene and Carbon Nanotube Composites
7.7 Porous Graphene Sponge Additives for Lithium Ion Batteries with Excellent Rate Capability
7.8 Conclusions and Perspective
References
Chapter 8: Graphene-Based Flexible Actuators, Sensors, and Supercapacitors
8.1 Introduction
8.2 IPGC Transducer for Actuators, Sensors, and Supercapacitors—Background and Basics
8.3 Electrochemical Actuators
8.4 Piezoionic Sensors
8.5 Supercapacitors
8.6 Summary and Future Development
Acknowledgments
References
Chapter 9: Graphene as Catalyst Support for the Reactions in Fuel Cells
9.1 Introduction
9.2 Synthesis of Graphene
9.3 Structural Properties and Functionalization of Graphene
9.4 Structural Characterizations of Graphene
9.5 Graphene Morphology
9.6 Carbon Materials as Catalyst Support
9.7 Promoting Effect of Carbon Functional Groups
9.8 Graphene as Catalyst Support
Acknowledgment
References
Chapter 10: Nitrogen-Doped Carbon Nanostructures as Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) Electrocatalysts in Acidic Media
10.1 Introduction
10.2 Pt-Free Electrocatalysts for ORR
10.3
In Situ
Characterization of the Pyrolytic Growth of CN
x
Catalysts
10.4 ORR Active Site Debate
10.5 Probing the ORR Active Sites over CN
x
Catalysts Using Phosphate Anion
10.6 Other Electrochemical Applications of CN
x
Catalysts
10.7 Concluding Remarks
Acknowledgments
References
Chapter 11: Recent Advances in Graphene-Based Materials for Photocatalytic H
2
Evolution
11.1 Introduction
11.2 Applications of Graphene-Based Photocatalytic Materials
11.3 The Role of Graphene in Photocatalytic Materials
11.4 Conclusion
References
Chapter 12: Graphene Thermal Functional Device and Its Property Characterization
12.1 Introduction
12.2 Fabrication of Suspended Graphene Electronic Devices
12.3 Electrical and Thermal Properties of Graphene
12.4 Thermal Rectification in Suspended Graphene
12.5 Conclusions
References
Chapter 13: Self- and Directed-Assembly of Metallic and Nonmetallic Fluorophors: Considerations into Graphene and Graphene Oxides for Sensing and Imaging Applications
13.1 Introduction
13.2 Graphene and Graphene-Based Functional Materials for Biosensing Applications
13.3 Graphene and Graphene-Based Materials for Biosensing Applications
13.4 Graphene and Graphene-Like Materials for Bioimaging Applications
13.5 Conclusions
References
Chapter 14: Stimuli-Responsive Graphene-Based Matrices for Smart Therapeutics
14.1 Introduction
14.2 pH-Responsive Systems
14.3 Magnetic Field Controlled Drug Delivery
14.4 Photothermal Triggered Drug Release
14.5 Electrochemically Controlled Release
14.6 Multimode Stimuli
14.7 Perspectives and Conclusions
References
Chapter 15: Application of Graphene Materials in Molecular Diagnostics
15.1 Introduction
15.2 Optical Strategies
15.3 FRET Strategies
15.4 Electrochemical Strategies
15.5 SPR Strategies
15.6 SERS Strategies
15.7 FET Strategies
References
Chapter 16: Graphene Oxide Membranes for Liquid Separation
16.1 Introduction
16.2 Pristine GO Membranes
16.3 Tuning Pore Size
16.4 Conclusions
References
Index
End User License Agreement
Guide
Cover
Table of Contents
Begin Reading
List of Illustrations
Chapter 1
Figure 1.1
TEM images of (a) graphene sheets. (b) Graphene sheets with Pd nanoparticles with…
Figure 1.2
(a) Image of the (rGO–PDDA
+
/rGO–O
−
)…
Figure 1.3
(a) SEM image of graphene wrapped-MnO
2
nanocomposites. (b) Specific…
Figure 1.4
Sensitivity of graphene to chemical doping. (a) Chemically induced charge carrier…
Figure 1.5
Graphene nanoplatelet-polymer chemiresistive sensor arrays for the detection and…
Figure 1.6
rGO-based multisensory array. (a) Optical photograph of a multielectrode KAMINA…
Figure 1.7
Gas sensing signals of (a) NO
2
and (b) NH
3
from rGO sensors…
Figure 1.8
(a) (Graphene-Ti
091
O
2
)
5
hollow spheres. Scale bar…
Figure 1.9
Proposed pathways for catalytic oxidation of HCHO over G-Mn hybrid nanostructure…
Figure 1.10
Cross-sectional-view (a) and top-view (b) SEM images of the SiNW array. Cross-se…
Figure 1.11
Photoresponse of substrate-free rGO film device under 532-nm light illumination…
Chapter 2
Figure 2.1
(a) FC curves and (b) WSDs and WVs of different lubricants. All tests were conducted…
Figure 2.2
SEM images of the worn surfaces on the steel balls lubricated with the different…
Figure 2.3
(a) Average friction coefficient and (b) WSD and WSW of graphene and MoS…
Figure 2.4
Effect of mass ratio of GO to SiO
2
on (a) coefficient of friction and…
Figure 2.5
Flank wear evolution after end milling of AISI-304 austenitic stainless steel…
Figure 2.6
Surface roughness under different feed rates and spindle speeds: (a) feed rate:…
Figure 2.7
SEM image of chip formation under two different coolants: (a) conventional coolant…
Figure 2.8
Mean of torque values under different lubrication conditions [15].
Figure 2.9
Micrographs of thread surface under different lubrication conditions: (a) under…
Figure 2.10
Trends in the cutting temperatures (a) and the cutting forces (b) [16].
Figure 2.11
(a) Cutting force and (b) surface roughness trends seen for the GOP colloidal…
Figure 2.12
(a) Cutting temperature and (b) cutting force trends over the length of cut for…
Figure 2.13
(a) Cutting temperature trace, (b) peak temperature rise of tool, and (c)…
Figure 2.14
(a) Variation of coefficient of friction between sliding pin and rotating disk…
Figure 2.15
(a) Horizontal grinding force as a function of graphite diameter and concentration…
Figure 2.16
Surface roughness as a function of graphite diameter and concentration, dispersing…
Figure 2.17
(a) Material removal rate (MRR), (b) electrode wear rate (EWR), and (c) surface…
Figure 2.18
Comparison of workpiece hardness with various compositions before and after EDM…
Figure 2.19
Optical image of the machined surfaces of different ceramic/carbon nanostructure…
Figure 2.20
Comparison of the edge sharpness of the machined hole on Si
3
N…
Chapter 3
Figure 3.1
GF synthesized by a self-assembly method. (a) Photographs of a GO aqueous…
Figure 3.2
Template-guide methods for GF fabrication. (a) Typical steps showing the Ni foam…
Figure 3.3
Digital photographs of (a) GO-based ink for 3D printing and (b) the printed GF…
Figure 3.4
Specific energy densities for different rechargeable batteries. (Reproduced with…
Figure 3.5
(a) Schematic illustration of the working mechanism for a rechargeable LIB. The…
Figure 3.6
Performance of GF hybrid for LIB anode. (a) Photograph of a flexible NGF-Ge@NG y…
Figure 3.7
GF composites for LIB cathode and flexible LIB. (a) SEM image, (b) cycling stability…
Figure 3.8
GF-Sb
2
S
5
anode for SIB. (a) SEM image of a GF-Sb…
Figure 3.9
GF for the cathode of AIB. (a) SEM images and (b) the cycling stability of the GF…
Figure 3.10
Schematic diagram of the composition of a Li–S battery. (Reproduced with…
Figure 3.11
GF supported sulfur cathode for Li–S battery. (a) Digital photograph of the…
Figure 3.12
Schematic illustration showing the structure and components of a metal-air battery…
Figure 3.13
GF-based cathodes for Li-air batteries. (a) Discharge/charge profiles of GF-Ru and…
Figure 3.14
Performance of a GF-AgNW-based Zn-air battery. (a) SEM image of GF-AgNW composite…
Figure 3.15
Performance of GF-based EDLC. (a) CV curves and (b) capacitance retention at…
Figure 3.16
(a) Schematic illustration of the molecular structures of thiourea functionalized…
Chapter 4
Figure 4.1
(a) Schematic fabrication of R-3DNG: (i) hydrothermal self-assembly of GO, melamine…
Figure 4.2
(a) Schematic illustration of the synthesis process of 3D (Ni, Co)Se
2
…
Figure 4.3
Schematic illustration of the fabrication of NiCo
2
O
4
on a…
Figure 4.4
(a) Schematic illustration of the synthesis of 3D-NG. (Reprinted with permission…
Figure 4.5
(a) Schematic illustration of the preparation of NCO/GNF. (Reprinted with permission…
Figure 4.6
The 3D graphene aerogel printing process. (a) 3D printing setup. (b) Ice support…
Figure 4.7
(a) SEM images of DL-3D-G (left), TL-3D-G (middle), and FL-3D-G (right), and the…
Figure 4.8
SEM (A) and TEM (B) images of PtNR/R-3DNG. CV curves with a scan rate of 50 mV s…
Figure 4.9
(a) TEM image of Pt/PdCu nanocubes supported on graphene. (b) HAADF-STEM image of…
Figure 4.10
(a) Schematic illustration of the fabrication of Pd
6
Co/3DG catalyst and…
Figure 4.11
HER activity of NS codoped nanoporous graphene (a–d). (a) CV curves of the…
Figure 4.12
(a) A structure sketch of layered MoS
2
nanosheets supported on a 3D….
Figure 4.13
(a) Schematic illustration of the preparation and application of Ni–Fe/3D…
Figure 4.14
Electrochemical reduction of CO
2
, coupled to renewable electricity…
Figure 4.15
3D model diagrams of 3D graphene-based sensing materials: 3D GF/BiNP film (left)…
Figure 4.16
(a) CV curves, (b) lines of charge versus t
1/2
, and (c) EIS measurements…
Figure 4.17
Scheme illustration of the fabrication process of Fe
3
O
4
/3DG…
Figure 4.18
(a) Current response of Ni(OH)
2
/3DGF at different potentials in 0.1 M…
Figure 4.19
(a) Current response of the freestanding 3D graphene with the successive addition…
Figure 4.20
(a) CVs of NiCo
2
O
4
supported on 3D graphene and carbon nanotube…
Figure 4.21
Low- (a, b) and high-magnification (c) SEM images of 3D graphene micropillars. (d)…
Figure 4.22
Schematic illustration of the preparation of 3DRGO and the application for CAP sensing…
Figure 4.23
(a) Schematic illustration for the preparation of CuO-NPs/3DGR/GCE and the electrochemical…
Chapter 5
Figure 5.1
(a) Schematic illustration and (b) long-term cyclability of Si/graphene composite…
Figure 5.2
(a) TEM image and (b) long-term cyclability of Sn/graphene composite. Reproduced…
Figure 5.3
(a) SEM image of SnO
2
/graphene composite. (b) SEM image corresponding…
Figure 5.4
(a) SEM, (b) TEM images, and (c) long-term cyclability of Fe
2
O…
Figure 5.5
(a) Schematic illustration, (b) corresponding SEM image, and (c) rate capability…
Figure 5.6
(a) TEM image and (b) long-term cyclability of Li
4
Ti
5
O
12
/graphene…
Figure 5.7
(a, b) Schematic illustrations and (c) long-term cyclability of the TiO…
Figure 5.8
(a) SEM image and (b) long-term cyclability of LiFePO
4
/graphene composite…
Figure 5.9
(a) Schematic illustration and (b) long-term cyclability of SnS
2
/rGO…
Figure 5.10
(a) Schematic illustration for the structural changes of the Sb–O–…
Figure 5.11
(a) Schematic illustration for the synthetic procedures, (b) TEM image, and (c)…
Figure 5.12
(a) Schematic illustration of a sodium storage mechanism in the TiO
2
/open…
Figure 5.13
(a) TEM image, (b) its scheme, and (c) rate capability of 3D hierarchical meso- and…
Figure 5.14
(a) Scheme of interaction between Li
2
S cluster and ethylenediamine…
Figure 5.15
(a) Scheme, (b) SEM image, and (c) long-term cyclability of S/graphene composite…
Figure 5.16
(a) Schematic illustration and SEM image of Li–S cell configuration with a…
Figure 5.17
(a) SEM image and (b) discharge–charge profiles of graphene electrode at 75…
Figure 5.18
(a) Schematic illustration for the synthetic procedures of porous graphene and…
Figure 5.19
(a) Discharge–charge profiles of α-MnO
2
/graphene at 200…
Chapter 6
Figure 6.1
Comparison of the different battery technologies in terms of volumetric and…
Figure 6.2
(a) The schematic of graphene structure. (b) The photo of flexible graphene…
Figure 6.3
A proposed schematic (Lerf–Klinowski model) of graphene oxide structure…
Figure 6.4
Optical photos of GO before (a) and after (b) treatment in a microwave oven for…
Figure 6.5
Schematic describing the nucleation and growth process of graphene grown on a…
Figure 6.6
(a) N1s XPS spectrum of the N-doped graphene. Inset: schematic structure of the…
Figure 6.7
(a) The schematic of preparing ASGFs, (b) the electrochemical performance of…
Figure 6.8
The fabrication of a layered Li–rGO composite film (a); galvanostatic…
Figure 6.9
(a) Schematic of GN added in the LiFePO
4
cathode materials;…
Figure 6.10
(a) Schematic of the electrochemistry and (b) charge/discharge voltage profile…
Figure 6.11
Schematic (a) and the electrochemical performance (b) of the G-NDHCS-S hybrids…
Figure 6.12
(a) The schematic representations of Li-ion, non-aqueous, and aqueous Li–…
Figure 6.13
(a) Schematic Illustration for synthesis of porous graphene and Ru-functionalized…
Chapter 7
Figure 7.1
Classification of supercapacitor.
Figure 7.2
Comparison of construction diagrams of three capacitors of (a) conventional…
Figure 7.3
Models of the electrical double layer at a positively charged surface: (a) the…
Figure 7.4
Two-electrode test configuration.
Figure 7.5
Comparison of different carbon materials as electrodes of supercapacitors. (a)…
Figure 7.6
Interaction of chemically reduced graphene and CNTs in water. (a) Dispersability…
Figure 7.7
Morphological and structural characterization of the various carbon electrodes…
Figure 7.8
Electrochemical properties of the various electrodes made of CNTs, graphene, and…
Figure 7.9
Comparison of electrochemical behaviors of the studied electrodes made of CNTs,…
Figure 7.10
Summary of electrochemical properties of CNTs, graphene, and graphene/CNT compos…
Figure 7.11
Specific capacitance of CNTs, graphene, graphene/CNT composite supercapacitors at…
Figure 7.12
(a) Cyclic voltammetry curves in ionic liquid at scan rate of 10, 20, 50, and 100…
Figure 7.13
(a) Cycling property of SWCNTs, graphene, and graphene/CNT composite electrodes…
Figure 7.14
Schematic illustrating the electroactivation to increase the electrode surface area…
Figure 7.15
Nitrogen adsorption isotherm of graphene/CNT composite. The inserted graph is…
Figure 7.16
Illustrative fabrication process of the composite electrode. The graphene was…
Figure 7.17
Morphology of graphene oxide and graphene. (a) SEM image of graphene oxide, (b)…
Figure 7.18
Morphology and structural characterization of as-coated MnO
2
graphene…
Figure 7.19
Electrochemical measurement of graphene electrode. (a) CV curves of the graphene…
Figure 7.20
Schematics illustrating coating of graphene with MnO
2
nanoflowers…
Figure 7.21
Electrochemical properties of graphene electrode after MnO
2
coating…
Figure 7.22
Comparison of various carbon structures as electrode material for supercapacitors…
Figure 7.23
Illustrative fabrication process of the composite materials. (a) The graphene and…
Figure 7.24
Morphological and structural characterization of various carbon materials. (a)…
Figure 7.25
Electrochemical properties of graphene/CNT based materials. (a) Galvanostatic…
Figure 7.26
Graphene/CNT/polyaniline coin cell configuration.
Figure 7.27
Illustrative fabrication process of the composite materials. (a) Single-layer…
Figure 7.28
Morphological and structural characterization of various graphene-based materials…
Figure 7.29
Electrochemical properties of graphene/CNT-based materials. (a) CV curves of…
Figure 7.30
Schematic diagram and the material synthesis process. (a) Digital photo of 0.1 g…
Figure 7.31
SEM images of (a) graphite raw materials for MG, (b) PreMG, and (c) MG and (d) TEM…
Figure 7.32
Representative AFM images and the cross-sectional high profiles of (a) PreMG and…
Figure 7.33
Nitrogen absorption isotherm of PreMG and MG. The inset graph is the pore size…
Figure 7.34
Raman spectroscopy of PreMG and MG. The inset compares (a) AvG, full width half…
Figure 7.35
XPS characterization of PreMG and MG. The inset graph is the quantitative…
Figure 7.36
ATR-FTIR characterization of PreMG and MG.
Figure 7.37
TPD-MS analysis of (a) PreMG and (b) MG.
Figure 7.38
Half-cell initial charge and discharge curves of the reference cell and cell…
Figure 7.39
Full-cell charge and discharge rate capability: (a) charge rate capability of…
Figure 7.40
Electrochemical impedance spectroscopy (EIS) analysis: (a) equivalent circuit,…
Figure 7.41
Rate cycling of reference cell and cell with MG at 1, 3, and 6 C.
Figure 7.42
Road map of supercapacitors.
Chapter 8
Figure 8.1
Schematic of graphene structure.
Figure 8.2
IPGC structure and its applications as actuator, sensor, and supercapacitor. (a)…
Figure 8.3
Mechanisms of IPGC based (a) actuator, (b) sensor, and (c) supercapacitor,…
Figure 8.4
Fabrication process of the graphene-based photoactuator and its application as…
Figure 8.5
(a) Large electrochemical strain induced by change of the atomic structure of…
Figure 8.6
Illustration of (a) ion insertion induced graphite expansion, (b) widely adopted…
Figure 8.8
Graphene-stabilized silver nanoparticle electrode-based IPGC actuator. (a)…
Figure 8.7
Graphene nanosheet/carbon nanotube hybrid electrode-based IPGC actuators. (a)…
Figure 8.9
Fabrication of the porous graphic carbon nitride electrode and its…
Figure 8.10
Schematic diagrams for the synthetic route of Th-SNG and the concept of a novel…
Figure 8.11
(a) Schematics of an electrolyte containing film sandwiched between metal electrodes…
Figure 8.12
(a) Illustration of structure and assembly procedure of the VANiONW@ RGO–…
Figure 8.13
(a) Schematic illustration for fabricating the PANI@VA-CNTs film. (b) Surface SEM…
Figure 8.14
Piezoionic effect showing inhomogeneous ionic distribution [83].
Figure 8.15
(a) Schematic diagram of the fabrication process of the IPMC piezoionic sensor…
Figure 8.16
Response of the IPGC piezoionic sensor. (a) SEM image of the graphene composite…
Figure 8.17
Applications of the piezoionic sensor as wearable sensor for the monitoring of…
Figure 8.18
Schematic of the fabrication process for holey-graphene-based IPGC sensor. (a)…
Figure 8.19
Sensing performance of holey-graphene-based IPGC sensor. (a) Working mechanism…
Figure 8.20
Large-scale and spatial movements monitoring. Relevant potential change of (a)…
Figure 8.21
Sign recognition of the ionic sensor arrays with smart glove. (a) Schematic for…
Figure 8.22
(a) Sensing signal about the movement of the bicipital muscle and triceps muscle…
Figure 8.23
(a) Schematic diagrams of IPGC supercapacitor at charged state. Reprinted with…
Figure 8.24
(a) Graphene–PANI composite-based electrode. Reprinted with permission…
Figure 8.25
(a) SEM image of the interconnected structure formed by the grapheme–CNT…
Figure 8.26
(a) Schematic illustration of nitrogen-doped mechanism in graphene. (b) Schematic…
Figure 8.27
(a) Scheme and photographs of the micro-SCs integrated into woven fabric and flexible…
Chapter 9
Figure 9.1
Structure of graphene (a) and graphene sheets (b).
Figure 9.2
Structure of graphite oxide layer by Lerf–Klinowski model. (Reprinted from…
Figure 9.3
Three common bonding configurations of nitrogen-doped graphene. (Reprinted from…
Figure 9.4
(a) XRD patterns, (b) Raman spectra, and (c) C1s XPS spectra for the graphite…
Figure 9.5
In situ
SEM images recorded at 1000°C during LP-CVD growth showing…
Figure 9.6
(a) Photograph of 3D graphene foam and (b) typical Raman spectra measured at…
Figure 9.7
(A) Deconvoluted XPS C1s spectra of the surface of polished (a) and oxidized (b)…
Figure 9.8
(A) Capacitances and CFG resistance (EEC-simulated data) of differently activated…
Figure 9.9
CV responses of Pt/RGO hybrids and Pt/C in N
2
-saturated (a) 1 M H…
Figure 9.10
(a) Dependence of I
f
/I
b
ratio on contribution of residual…
Chapter 10
Figure 10.1
Examples of nitrogen species on the surface of carbon-based ORR electrocatalysts…
Figure 10.2
Carbon nanostructures and corresponding TEM images of materials synthesized in…
Figure 10.3
Normalized
in situ
XANES spectra of Co K-edge during the growth of CN…
Figure 10.4
XAFS characterization of CN
x
grown on Co/VC and Co/MgO substrates…
Figure 10.5
Effect of CO exposure on ORR activity of (a) CN
x
and (b) FeNC catalysts:…
Figure 10.6
DRIFT spectra obtained over FeNC (left) and CN
x
(right) catalysts under…
Figure 10.7
ORR activity measurements by RDE in 0.5 M H
2
SO
4
for (a)…
Figure 10.8
N 1s region of the X-ray photoelectron spectra for untreated and H
2
…
Figure 10.9
Fe K-edge XAS spectra for CN
x
and FeNC before and after H
2
…
Figure 10.10
Comparison of ORR RRDE results for unwashed and acid-washed catalysts at 1600 rpm…
Figure 10.11
Effect of acid washing on magnetization as a function of field at 300 K for…
Figure 10.12
N1 s XPS spectra of CN
x
before and after acid washing.
Figure 10.13
N1 s XPS spectra of FeNC before and after acid washing. Adapted by permission…
Figure 10.14
FT magnitudes of Fe–K edge of (a) CN
x
-unwashed, (b)…
Figure 10.15
Deconvoluted Mössbauer spectra for CN
x
before and after acid…
Figure 10.16
Deconvoluted Mössbauer spectra for FeNC before and after acid washing…
Figure 10.17
Polarization curves of CN
x
catalyst before and after soaking in 0.1 M…
Figure 10.18
(a) Mass-transport corrected ORR polarization curves for CN
x
catalyst…
Figure 10.19
(a) Transmission IR and (b) Raman spectra for CNx soaked in 0.1 M H
3
…
Figure 10.20
P 2p and N 1s XPS regions for CNx catalyst (a) before and (b) after soaking in…
Figure 10.21
Correlation between the loss in i
K
and the loss in pyridinic-N site…
Figure 10.22
(a) Electrochemically active hydroquinone (right)–quinone (left) reduction…
Figure 10.23
Reduction sweep voltammograms for CN
x
and Pt/VC in 0.5 M H…
Figure 10.24
RDE polarization curves of Pt/C, Rh
x
S
y
/C, and CN…
Figure 10.25
Stability testing of CN
x
in 0.5 M HCl. (a) Potential at –0.1…
Figure 10.26
Polarization curves of CNx, Ir/C, and Pt/C samples for (a) ORR and (b) OER. Inset…
Figure 10.27
(a) High potential regions of the cathodic polarization curves and (b) mass-tran…
Figure 10.28
Correlation of relative distribution of pyridinic-N functionalities to ORR (a)…
Chapter 11
Figure 11.1
Schematic energy level diagrams of GO samples of different oxidation levels…
Figure 11.2
The schematic diagram of the photocatalytic mechanism for hydrogen generation of…
Figure 11.3
The schematic diagram of charge carrier transfer in the [ZnTMPyP]
4+
…
Figure 11.4
(a) Schematic illustration of the charge transfer in the MoS
2
/G-CdS…
Figure 11.5
The proposed mechanism for graphene-based photocatalysts in photocatalytic…
Figure 11.6
Schematic diagram for charge carrier separation on Pt-graphene-Sr
2
Ta…
Figure 11.7
Schematic diagram of the preparation procedure of r-NGOT and r-LGOT. Reprinted…
Figure 11.8
The Nyquist plots of ZnIn
2
S
4
and…
Figure 11.9
Schematic illustration of the charge transfer in TiO
2
/MG composites…
Chapter 12
Figure 12.1
Fabrication route for making suspended graphene ribbon with electrodes…
Figure 12.2
Scanning electron microscope (SEM) images of suspended graphene with metallic…
Figure 12.3
Zoom-in SEM images of suspended graphene ribbons. The width of graphene ribbon…
Figure 12.4
SEM images of suspended graphene ribbon with scrolling edges. The yellow and…
Figure 12.5
Raman spectra of the graphene sample before and after suspending. Reproduced…
Figure 12.6
Prepared suspended graphene samples for electrical measurement. Reproduced with…
Figure 12.7
In situ
measurement of current annealing on suspended graphene. Reproduced…
Figure 12.8
Temperature distribution of the suspended graphene along with the electrode pad and…
Figure 12.9
Electrical conductivity of suspended graphene ribbon as a function of bias voltage…
Figure 12.10
Breakdown of suspended graphene at high bias voltage. The right figure is the SEM…
Figure 12.11
SEM images of two suspended graphene ribbon with different surface cleanness…
Figure 12.12
Raman spectra of two samples with different surface cleanness. Reproduced with…
Figure 12.13
Charge mobility of clean graphene as a function of gate voltage. The dashed one…
Figure 12.14
(a) Schematic diagram of indirect FIB irradiation on suspended graphene; (b)…
Figure 12.15
Charge mobilities of graphene samples with and without artificial defects…
Figure 12.16
SEM images of six suspended single-layer graphene (SLG) samples. Reproduced with…
Figure 12.17
Principle of T-type sensor for measuring thermal conductivity of graphene. (a)…
Figure 12.18
Temperature distribution of the T-type sensor with and without graphene ribbon…
Figure 12.19
Thermal conductivities of six suspended graphene samples. Reproduced with…
Figure 12.20
Nanopores in graphene made by FIB irradiation. (a–c) sample #5 after 0, 1…
Figure 12.21
Thermal conductivity of graphene with nanopores. Reproduced with permission from…
Figure 12.22
Width-dependent thermal conductivity of graphene. Reproduced with permission…
Figure 12.23
SEM images of the H-type sensor with suspended graphene ribbon. Reproduced with…
Figure 12.24
Temperature distribution of the H-type sensor with graphene ribbon. (a)…
Figure 12.25
Resistance changes of two sensors as a function of heating power. Reproduced…
Figure 12.26
SEM images of suspended graphene ribbon with and without nanopores. Reproduced…
Figure 12.27
Thermal conductivities of graphene samples #1, #2, and #3 in two heat flow…
Figure 12.28
Physical mechanism of thermal rectification in defective graphene ribbons…
Figure 12.29
SEM images of graphene ribbon with asymmetric structures. Reproduced with…
Figure 12.30
Thermal conductivities of graphene samples #4 and #5 in two heat flow directions…
Figure 12.31
MD simulation result of the trapezoid graphene sample #5. (a) Calculation model of…
Figure 12.32
MD simulation result of the particle deposition sample #5. (a) Calculation model…
Chapter 13
Figure 13.1
Scheme of a biosensor. The biosensor consists of a receptor layer, which consists…
Figure 13.2
(a) Schematic representation of the FRET mechanism, its disruption, and the role…
Figure 13.3
Schematic illustration of the FRET assays proposed by Feng [50] for the detection…
Figure 13.4
Schematic representation of the organic pollutants detection (a) and digital images…
Figure 13.5
Illustration of a GO-based immuno-biosensor. Reproduced with permission from Ref…
Figure 13.6
Preparation of the rGO–PAMAM–MWCNT–AuNP nanohybrid material…
Figure 13.7
Construction process of the photoelectrochemical sandwich immunosensor. Reproduced…
Figure 13.8
Schematic illustration of a sandwich electrochemical biosensor for MCF-7 detection…
Figure 13.9
(a)
In vivo
distribution of graphene oxide–polyethylene glycol…
Figure 13.10
(a) Schematic representation of the NIR emitting vascular endothelial growth factor…
Figure 13.11
Evaluation of the rGO-IONP-PEG composite as multimodal probe and biodistribution…
Figure 13.12
(a) Image of mouse with MCF-7 xenografted tumor; (b) ultrasound image of the area…
Figure 13.13
(a) Preparation of GO-wrapped gold nanorods (GO@AuNRs) functionalized with doxorubicin…
Chapter 14
Figure 14.1
Graphene-based nanomaterials family for drug delivery: Chemical structures of some…
Figure 14.2
Release strategies of drugs from graphene matrices and their advantages and…
Figure 14.3
Preparation of various curcumin–graphene composites by adsorption of Cur…
Figure 14.4
(a) The preparation process of magnetic graphene nanohybrid and the mechanism of…
Figure 14.5
(A) (a) Percentage of DOX released from DOX-loaded rGO/dopa-MAL-cRGDfC…
Figure 14.6
(A) Effect of voltage stimulus modulation on the amount of DEX released from a…
Figure 14.7
Illustration of the PEG–NGO–Pt nanocomposite as a multifunctional…
Chapter 15
Figure 15.1
Schematic representation of the target-induced fluorescence change of the…
Figure 15.2
Schematic illustration for the developed GO-based photoinduced charge transfer…
Chapter 16
Figure 16.1
Ion permeation through GO laminates. (a) Photograph of a GO membrane covering a…
Figure 16.2
Sieving through the GO membrane. The permeation rates are normalized per 1 M…
Figure 16.3
Proposed conceptual interlayer nanostructures of GO membranes prepared by slow…
Figure 16.4
GO encapsulated using Stycast epoxy. (a) Optical micrograph of the cross-section…
Figure 16.5
Illustration of the fabrication process of the NSC-GO membrane. A multistep…
Figure 16.6
(a) Permeation fluxes of metal chlorides (0.05 M) through propandioic acid cross…
List of Tables
Chapter 3
Table 3.1
Physical properties of GF fabricated by different methods (σ-electrical…
Table 3.2
Performance of GF-based anodes in LIB.
Table 3.3
Summary of the GF-based composites for SC applications.
Chapter 4
Table 4.1
Determination of carbaryl in real samples [203].
Chapter 7
Table 7.1
A summary of graphene supercapacitor.
Table 7.2
Values of specific capacitance (F/g) depending on cell type.
Chapter 13
Table 13.1
Summary of the recent donor–acceptor FRET assays based on graphene derivatives…
Chapter 14
Table 14.1
Some examples of drugs loaded onto graphene-based matrices together with…
Table 14.2
Interactions between graphene nanomaterials and drugs for efficient loading.
Table 14.3
Examples of therapeutic graphene-based nanocomposites based on drug release by…
Pages
Cover
ii
iii
iv
xv
xvi
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
Scrivener Publishing100 Cummings Center, Suite 541JBeverly, MA 01915-6106
Publishers at ScrivenerMartin Scrivener ([email protected])Phillip Carmical ([email protected])
Handbook of Graphene comprises 8 volumes:
Volume 1: Growth, Synthesis, and FunctionalizationEdited by Edvige Celasco and Alexander ChaikaISBN 978-1-119-46855-4
Volume 2: Physics, Chemistry, and BiologyEdited by Tobias StauberISBN 978-1-119-46959-9
Volume 3: Graphene-Like 2D MaterialsEdited by Mei ZhangISBN 978-1-119-46965-0
Volume 4: CompositesEdited by Cengiz OzkanISBN 978-1-119-46968-1
Volume 5: Energy, Healthcare, and Environmental ApplicationsEdited by Cengiz Ozkan and Umit OzkanISBN 978-1-119-46971-1
Volume 6: Biosensors and Advanced SensorsEdited by Barbara PalysISBN 978-1-119-46974-2
Volume 7: BiomaterialsEdited by Sulaiman Wadi HarunISBN 978-1-119-46977-3
Volume 8: Technology and InnovationEdited by Sulaiman Wadi HarunISBN 978-1-119-46980-3
Handbook of Graphene
Volume 5: Graphene in Energy, Healthcare, and Environmental Applications
Edited by
Cengiz Ozkan
Department of Materials Science & Engineering, University of California, Riverside, USA
and
Umit Ozkan
Chemical and Biomolecular Engineering, Ohio State University, Columbus, USA
This edition first published 2019 by John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA and Scrivener Publishing LLC, 100 Cummings Center, Suite 541J, Beverly, MA 01915, USA © 2019 Scrivener Publishing LLC For more information about Scrivener publications please visit www.scrivenerpublishing.com.
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.
Wiley Global Headquarters111 River Street, Hoboken, NJ 07030, USA
For details of our global editorial offices, customer services, and more information about Wiley products visit us at www.wiley.com.
Limit of Liability/Disclaimer of WarrantyWhile the publisher and authors have used their best efforts in preparing this work, they make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials, or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read.
Library of Congress Cataloging-in-Publication Data
ISBN 978-1-119-46971-1
Preface
Despite being just a one-atom-thick sheet of carbon, graphene is one of the most valuable nanomaterials. Initially discovered through scotch-tape-based mechanical exfoliation, graphene can now be synthesized in bulk using various chemical techniques. Counted among the contrasting properties of this remarkable material are its light weight, thinness, flexibility, transparency, strength, and resistance, along with superior electrical, thermal, mechanical, and optical properties. Due to these novel traits, graphene has attracted attention for use in cutting-edge applications in almost every area of technology, which are projected to change the world.
The Handbook of Graphene is presented in a unique eight-volume format covering all aspects relating to graphene—its development, synthesis, application techniques, and integration methods; its modification and functionalization, its characterization tools and related 2D materials; physical, chemical, and biological studies of graphene and related 2D materials; graphene composites; use of graphene in energy, healthcare, and environmental applications (electronics, photonics, spintronics, bioelectronics and optoelectronics, photovoltaics, energy storage, fuel cells and hydrogen storage, graphene-based devices); and its large-scale production and characterization, as well as graphene-related 2D material innovations and their commercialization.
This fifth volume of the handbook is solely focused on graphene in energy, healthcare, and environmental applications. Some of the important topics include but are not limited to graphene nanomaterials in energy and environment applications; graphene as nanolubricant for machining, three-dimensional graphene foams for energy storage applications; three-dimensional graphene materials: synthesis and applications in electrocatalysts and electrochemical sensors; graphene and graphene-based hybrid composites for advanced rechargeable battery electrodes; graphene-based materials for advanced lithium-ion batteries; graphene-based materials for supercapacitors and conductive additives of lithium-ion batteries; graphene-based flexible actuators, sensors, and supercapacitors; graphene as catalyst support for the reactions in fuel cells; nitrogen-doped carbon nanostructures as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts in acidic media; graphene-based materials for photocatalytic H2 evolution; graphene thermal functional device and its property characterization; self- and directed-assembly of metallic and nonmetallic fluorophors: considerations into graphene and graphene oxides for sensing; stimuli-responsive graphene-based matrices for smart therapeutics; application of graphene materials in molecular diagnostics; and graphene oxide membranes for liquid separation.
In conclusion, thank you to all the authors whose expertise in their respective fields have contributed to this book as well as a sincere appreciation to the International Association of Advanced Materials.
February 16, 2019
Chapter 1Graphene Nanomaterials in Energy and Environment Applications
Mingqing Yang, Hua Tian, Jiayi Zhu and Junhui He*
Functional Nanomaterials Laboratory, Center for Micro/Nanomaterials and Technology and Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences (CAS), Beijing, China
*Corresponding author: [email protected]
Abstract
In the 21st century, aggravating energy and environmental problems such as fossil fuel depletion, global warming, and pollution are ringing the alarm bell to the human society. Thus, green energy and environment technologies have been the urgent and important areas. Among several possible alternatives for fossil energy, eventually solar energy is probably the only one that can meet the multifold demand for long-term human needs. The utilization of solar energy consists of two steps: First, solar energy can be effectively converted to applicable forms (electricity or fuel) from solar power to suppress energy crisis and global warming. Aiming at this goal, solar cells and photocatalysts for production of H2 and reduction of CO2 are mostly concerned. Second, high-performance energy storage devices are also required. This is mainly due to the intermittent characteristics of solar energy and other renewable energy sources. Supercapacitor is one of the promising devices for this purpose. Nanoscience and nanotechnology are interdisciplinary fields that bring together physicists, chemists, materials scientists, biochemists, and engineers to meet the challenges that humankind faces. Among the current subjects in nanoscience and nanotechnology, nanomaterials are developing fast and explosively and attract a huge amount of attention. Nowadays, a variety of nanomaterials have been employed to solve the energy and environmental problems. Among them, graphene, a single layer of two-dimensional network of hexagonal structured sp2-hybridized carbon atoms, has shown many unique properties, such as the quantum Hall effect, high carrier mobility at room temperature, large theoretical specific surface area, good optical transparency, high Young’s modulus, and excellent thermal conductivity. Furthermore, it has high chemical stability and can be produced in a low-cost, controlled, scalable, and reproducible manner. Thus, graphene has been useful in various energy and environment applications, such as solar cells, high-performance electrodes in supercapacitors, degradation of organic pollutants, catalysts for reduction of CO2, chemical sensors for pollutants, and broadband photodetectors. In this chapter, we will systematically review the synthesis of graphene-based materials and their applications in energy- and environment-related fields described above. Some future research perspectives and new challenges that the field will have to address are also discussed.
Keywords: Graphene, energy, environment, solar cell, catalyst, supercapacitor, sensor, photodetector
1.1 Introduction
With the development of economy and society, aggravating energy and environmental problems such as fossil fuel depletion, global warming, and pollution are ringing the alarm bell to the human society. Thus, green energy and environment technologies have been the urgent and important areas. Among several possible alternatives for fossil energy, eventually solar energy is probably the only one that can meet the multifold demand for long-term human needs. The utilization of solar energy consists of two steps: First, solar energy can be effectively converted to applicable forms (electricity or fuel) from solar power to suppress energy crisis and global warming. Aiming at this goal, solar cells and photocatalysts for production of H2 and reduction of CO2 are mostly concerned [1–6]. Second, high-performance energy storage devices are also required. This is mainly due to the intermittent characteristics of solar energy and other renewable energy sources. Supercapacitor is one of the promising devices for this purpose [7–9]. On the other hand, the demand for developing reliable gas sensors is huge for applications in areas such as environmental monitoring, agriculture, medical diagnosis, and industrial wastes management. The detection of gas molecules such as nano-nitrogen oxides (nitric oxide, NO), nitrogen dioxide (NO2), formaldehyde (HCHO), ammonia (NH3), carbon monoxide (CO), etc. is necessary in many fields especially in environmental monitoring due to their toxicity and associated risk to the ecosystem [10–14]. So far, the sensing material becomes one of the essential issues toward achieving high-performance gas sensors.
The exponential growth of graphene research in both the scientific and engineering communities has taken place after the Geim group isolated “free” and “perfect” graphene sheets and demonstrated the unprecedented electronic properties of graphene in 2004 (Graphene, 2010 Nobel Prize for Physics) [15]. Graphene, a single layer of two-dimensional carbon lattice, has shown many unique properties, such as the quantum Hall effect (QHE), high carrier mobility at room temperature (~10,000 cm2 V−1 s−1), large theoretical specific surface area (~2630 m2 g−1), good optical transparency (~97.7% per layer), high Young’s modulus (~1 TPa), and excellent thermal conductivity (~3000–5000 W m−1 K−1) [16–20]. To exploit these properties in various kinds of application, several synthetic routes have been developed for the preparation of graphene and its derivatives, ranging from the bottom-up epitaxial growth to the top-down exfoliation of graphite. In particular, chemical exfoliation and reduction starting from the oxidation of graphite is an efficient process to produce graphene sheets in a low-cost, scalable, controllable, and reproducible manner. Owning to the highly versatile and tunable properties, graphene has attracted a great deal of attention in many important applications, such as optoelectronic devices, energy storage materials, catalysis, chemical and biological sensors, and polymer composites [21–28].
Due to highly remarkable properties, graphene has been useful in various energy and environment applications, such as transparent conductive electrodes or active materials in thin film solar cells, high-performance electrodes in supercapacitors, catalysts for reduction of CO2 and degradation of organic pollutants, gas sensors for polluting gases, and broadband photodetectors. This chapter mainly focuses on recent advances in the synthesis of graphene and graphene-based materials and their applications in energy- and environment-related fields described above.
1.2 Preparations of Graphene-Based Materials
1.2.1 Graphene
Geim and coworkers at the University of Manchester reported the isolation of graphene sheets by mechanical exfoliation of highly oriented pyrolytic graphite (this method is commonly known as the Scotch tape method) [15]. Since then, graphene has become the topic of extensive research for scientists around the globe due to its fascinating structural, electrical, optical, and mechanical properties. Now, graphene can be synthesized by various methods. These methods can be generally classified into the bottom-up and top-down approaches.
The bottom-up approach involves the direct synthesis of graphene materials from the carbon sources, such as the chemical vapor deposition (CVD), which is a typical method used to grow large-area, single- and few-layer graphene sheets on metal substrates. When the metal surfaces are heated, hydrocarbon (or carbon oxide) decomposes into carbon atoms and hydrogen gas (or oxygen gas), and the carbon atoms then form a graphene monolayer. Furthermore, the obtained graphene films on metal surface can be transferred to other target substrates via metal etching, which is very important for device applications [29]. The epitaxial growth process has also been exploited to prepare single-layer graphene via the sublimation of SiC. This process can provide a higher yield with much less defects, but cannot easily fabricate a large-area graphene. In addition to the above methods based on the solid-phase deposition, graphene is also obtainable via the wet chemical reaction of ethanol and sodium followed by pyrolysis, or through the organic synthesis to give graphene-like polyaromatic hydrocarbons [30, 31]. Different from the bottom-up approaches, the top-down approaches are advantageous in terms of high-yield, solution-based processability, and ease of implementation. Chemical exfoliation and reduction starting from the oxidation of graphite is an efficient process to produce graphene sheets in a low-cost, controlled, scalable, and reproducible manner. The procedure is through three steps: oxidation of graphite, exfoliation of graphite oxide into graphene oxide, and reduction of graphene oxide [32]. Unzipping carbon nanotubes (CNTs) can offer the possibility of large-scale production of narrow graphene nanoribbons with well-controlled widths. Some unzipping methods, such as oxidative treatment of CNTs and cutting of CNTs induced by transition metal nanoparticles, have been developed to effectively unzip CNTs to form graphene nanoribbons [33–35]. Although significant progress has been witnessed in developing the methods of fabricating graphene materials, the controllable production of graphene materials with desirable size, shape, and quality in a low-cost, scalable, and reproducible manner is still an essential technological challenge for graphene potential applications in different fields.
1.2.2 Graphene-Based Composites
In graphene-based composites, graphene generally acts either as a functional component or a substrate for immobilizing other components. The high surface area and the conductive robust structure of graphene often facilitate charge transfer and redox reaction, as well as enforce the mechanical strengths of composites. Therefore, anchoring redox active materials and photocatalysts on graphene would improve the performances of the composites for energy conversion and storage devices and/or degradation of organic pollutants [36–38]. As metal oxides are dispersed on reduced GO, the size of metal oxide nanoparticles can be nanometer scale without aggregation, showing much stability under reduction/oxidation electrochemical environments. Then their catalytic activity and durability can drastically increase as compared with their aggregated materials. Thus, highly electrochemically active graphene hybrid materials with SnO2, MnO2, Mn3O4, Co3O4, and Fe3O4, etc., have been exploited for electrochemical energy storage such as lithium-ion batteries and supercapacitors [27, 39].
Methods for fabricating graphene-based composites used in energy and environment applications can be classified into two general strategies: in situ reaction and ex situ hybridization. For example, many graphene-based composites with organic or inorganic nanoparticles were prepared via in situ chemical reactions. As seen from Figure 1.1a and b, in chemical syntheses, positively charged metal ions (e.g., Pd2+) preferably adsorbed on negatively charged rGO sheets via electrostatic interactions [40]. Therefore, metallization occurred preferentially on rGO sheets to form the corresponding composite materials. Negatively charged ions, such as PtCl42-, can also be reduced to metal nanoparticles on rGO sheets. Besides, if graphene is a reactant (e.g., reducing MnO4− by graphene), the reaction is self-limited on the surface of graphene sheets. On the other hand, the ex situ hybridization involves the mixing of graphene sheets and presynthesized or commercially available nanocrystals in solutions. rGO sheets are usually dispersible in water or various organic solvents. Furthermore, graphene can be easily functionalized into either positively or negatively charged derivatives. Thus, they can form composites with other charged components via electrostatic assembly. In our work, we reported a facile approach to fabricate novel graphene wrapped-MnO2 nanocomposites by coassembly between honeycomb MnO2 nanospheres and graphene sheets via electrostatic interaction [21]. As seen from Figure 1.1c and d, the graphene wrapped-MnO2 nanocomposites show crinkled and rough textures, which is associated with the presence of flexible and ultrathin graphene sheets. The honeycomb MnO2 nanospheres are firmly attached to the graphene sheets. Based on the above techniques, graphene-based composites with various functions have been successfully prepared.
Figure 1.1 TEM images of (a) graphene sheets. (b) Graphene sheets with Pd nanoparticles with a worm-like shape ~4 nm in width. (c, d) SEM and TEM images of graphene wrapped-MnO2 nanocomposites. Reproduced from Refs. [21] and [40].
1.3 Applications of Graphene-Based Materials in Energy and Environment
1.3.1 Solar Cells
Solar cell can directly convert solar energy to electrical power. Thus, it is one of the most promising devices satisfying the global energy requirements. As a novel and unique star among carbon nanomaterials, graphene manifests attractive application potentials in thin film, dye-sensitized, as well as heterojunction solar cells [41].
Graphene, a single layer of two-dimensional carbon lattice, exhibits remarkable optoelectronic properties as well as excellent chemical resistance and mechanical flexibility, and is considered to be an ideal candidate to replace indium tin oxide (ITO) for transparent electrodes. Several methods have been developed for the preparation of large-area graphene films to satisfy optoelectronic applications. Generally, there are mainly two strategies to prepare graphene-based transparent electrodes: solution-based assembly of rGO sheets into thin films and CVD fabrication of large-size continuous graphene films. The solution-based assembly of rGO sheets into thin films has several advantages. On one hand, the starting material of rGO is usually low-cost and abundant graphite; on the other hand, it is facile to process rGO sheets into a large-area film via wet processing techniques (e.g., spin coating, dip coating, LbL assembly, or vacuum filtration) [42–45]. We reported a new approach to fabrication of flexible, transparent conductive thin films via LbL assembly of oppositely charged rGOs and benign step-by-step post-treatment [46]. The graphene thin films showed remarkable optical and electronic properties as well as good electrical conductivities even under excessively multiple-cycle bending conditions, as seen from Figure 1.2a and b. This could be attributed to the superior structural properties of graphene sheets, such as flexibility, mechanical stability, and high tendency to stack together via π–π stacking. In contrast, the ITO on flexible substrate showed significant loss of electrical conductivity after multiple cycles of bending, which should be due to an increased number of cracks in the rigid inorganic structure of ITO under identical bending conditions. However, the conductivity and transparency of solution-based assembled rGO thin films are still far from the requirements of practical applications as transparent conductive electrodes for solar cells (sheet resistance < 100 Ω sq−1, transmittance > 90%). However, the production of large-area continuous graphene films may circumvent the above problem. As seen from Figure 1.2c and d, Wang et al. fabricated a large-area graphene film using a CVD process [47]. For graphene film with transmittance of 91–72% in the visible light wavelength range, the average sheet resistance varied from 1350 to 210 Ω sq−1, which is lower than that of the solution-based assembled rGO thin films by a factor of 2–3. Furthermore, they exploited the graphene film as a photo-anode for the organic photovoltaic device. The performance of the photovoltaic cell was measured and the graphene anode exhibited excellent performance characteristics (Voc=0.55 V, Jsc=6.05 mA cm−2, FF=51.3%, and PCE=1.71%). Under the same conditions, the photovoltaic performance of a reference device made with ITO anode showed Voc, Jsc, FF, and PCE of 0.56 V, 9.03 mA cm−2, 61.1%, and 3.10%, respectively. This indicates that the solar cell with a graphene anode has reached 55.2% PCE of a structurally identical cell with ITO anode.
Figure 1.2 (a) Image of the (rGO–PDDA+/rGO–O−)30 film on a PET substrate during the bending test (inset: left is blank PET and right is PET with the (rGO–PDDA+/rGO–O−)30 film). (b) The change in the resistance ratio (R/R0) of (rGO–PDDA+/rGO–O−)30 on PET (dark line) and ITO on PET (red line) with the number of bending cycles at an angle of 180°. (c, d) Schematic and energy diagram of the fabricated device with the structure of graphene/PEDOT:PSS/P3HT:PCBM/LiF/Al. Reproduced from Refs. [46] and [47].
The electron donor/acceptor layer is one of the most important components in a polymer-based thin film solar cell, which contains a conjugated polymer (e.g., poly(3-hexyl)thiophene, P3HT) to generate electron–hole pairs upon photon absorption, and an acceptor with a relatively high electron affinity to dissociate the electron–hole pairs into separate charges [48]. Owing to its large surface area for donor/acceptor interfaces and continuous pathway for electron transfer, graphene-based materials are anticipated to be used for the effective electron–hole separation and charge transport when blended with conjugated polymers. Recently, functionalized graphene has been explored as an electron acceptor for OPV devices [49].
Direct connection between the cathode and anode by the electron donor/acceptor layer will result in the fast recombination of charge carriers and current leakage. Therefore, a hole transport layer is usually incorporated between the anode and the electron donor/acceptor layer, such as the commonly used poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)(PEDOT: PSS). GO film could be used as a simple and effective alternative to PEDOT: PSS in polymer-based thin film solar cells. In the configuration of glass/PBASE-ITO/GO/P3HT:PCBM/Al, the GO film with a band gap of ~3.6 eV is able to hinder the electron transport from the PCBM LUMO to the ITO anode, while bridging the holes to the anode. Besides, the investigation into the effects of film thickness on the performance of polymer-based thin film solar cells was also discussed [2, 50].
In order to partially replace silicon, thus reducing cost in solar cell devices, carbon-based materials have been attempted in the p-type amorphous carbon/n-type silicon (p-AC/n-Si) heterojunctions and CNT/Si heterojunctions. Recently, we fabricated heterojunction structures, which consisted of a double-walled carbon nanotube (DWCNT) thin film coated either on an n-type silicon wafer or an n-type silicon nanowires (SiNW) array with varied lengths. We found that the photoresponse of the heterojunctions dramatically depends on the length of SiNWs. The heterojunction with a SiNW length of ca. 600 nm has the highest photoresponse value of 10.72. The heterojunction also showed fast photocurrent response (<10 ms) with good reproducibility [51].
Besides, graphene-based films can be prepared with controlled thickness, good surface continuity, and tunable properties via variable functionalizations. CVD grown graphene sheets had been deposited on n-Si with 100% coverage to make the Schottky junction solar cell, which showed an efficiency of up to ~1.5% with a filling factor of ~56%. In addition, the graphene film served as a semitransparent electrode for the graphene/n-Si solar cells [52].
1.3.2 Supercapacitors
Supercapacitors are charge-storage devices that have been attracting tremendous attention due to their high power density, excellent reversibility, and long cycle life. A high-performance supercapacitor should have high energy density (~1–10 Wh/kg, determined by its capacitance and voltage), high power density (~103–105 W/kg, determined by its voltage and internal resistance), and ultra-long cycling life (>100,000 cycles) [53–55]. Thus, supercapacitors are considered to be promising power supplies for versatile applications such as environmentally friendly automobiles, artificial organs, high-performance portable electronics, etc.
