Handbook of Graphene, Volume 5

Energy, Healthcare, and Environmental Applications

Cengiz Ozkan, Umit S. Ozkan, Cengiz Ozkan, Umit S. Ozkan

• Publisher: Wiley-Scrivener
• Year: 2019
• Print ISBN: 9781119469711
• eBook ISBN: 9781119469735
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

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.

Chapter 1
Graphene 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 v...

Table of contents

• Cover
• Title Page
• Copyright
• Preface
• Chapter 1: Graphene Nanomaterials in Energy and Environment Applications
• Chapter 2: Graphene as Nanolubricant for Machining
• Chapter 3: Three-Dimensional Graphene Foams for Energy Storage Applications
• Chapter 4: Three-Dimensional Graphene Materials: Synthesis and Applications in Electrocatalysts and Electrochemical Sensors
• Chapter 5: Graphene and Graphene-Based Hybrid Composites for Advanced Rechargeable Battery Electrodes
• Chapter 6: Graphene-Based Materials for Advanced Lithium-Ion Batteries
• Chapter 7: Graphene-Based Materials for Supercapacitors and Conductive Additives of Lithium Ion Batteries
• Chapter 8: Graphene-Based Flexible Actuators, Sensors, and Supercapacitors
• Chapter 9: Graphene as Catalyst Support for the Reactions in Fuel Cells
• Chapter 10: Nitrogen-Doped Carbon Nanostructures as Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER) Electrocatalysts in Acidic Media
• Chapter 11: Recent Advances in Graphene-Based Materials for Photocatalytic H2 Evolution
• Chapter 12: Graphene Thermal Functional Device and Its Property Characterization
• Chapter 13: Self- and Directed-Assembly of Metallic and Nonmetallic Fluorophors: Considerations into Graphene and Graphene Oxides for Sensing and Imaging Applications
• Chapter 14: Stimuli-Responsive Graphene-Based Matrices for Smart Therapeutics
• Chapter 15: Application of Graphene Materials in Molecular Diagnostics
• Chapter 16: Graphene Oxide Membranes for Liquid Separation
• Index
• End User License Agreement