Graphene, one-atom-thick planar sheet of carbon atoms densely packed in a honeycomb crystal lattice, has grabbed appreciable attention due to its exceptional electronic and optoelectronic properties. The reported properties and applications of this two-dimensional form of carbon structure have opened up new opportunities for the future devices and systems. Although graphene is known as one of the best electronic materials, synthesizing single sheet of graphene has been less explored. This review article aims to present an overview of the advancement of research in graphene, in the area of synthesis, properties and applications, such as field emission, sensors, electronics, and energy. Wherever applicable, the limitations of present knowledgebase and future research directions have also been highlighted.

Synthesis of Graphene and Its Applications: A Review

Graphene is a true wonder material that promises much in a variety of applications that include electronic devices, supercapacitors, batteries, composites, flexible transparent displays and sensors. This review highlights the different methods available for the synthesis of graphene and discusses the viability and practicalities of using the materials produced via these methods for different graphene-based applications.

Graphene synthesis: relationship to applications.

This review examines the properties of graphene from an experimental perspective. The intent is to review the most important experimental results at a level of detail appropriate for new graduate students who are interested in a general overview of the fascinating properties of graphene. While some introductory theoretical concepts are provided, including a discussion of the electronic band structure and phonon dispersion, the main emphasis is on describing relevant experiments and important results as well as some of the novel applications of graphene. In particular, this review covers graphene synthesis and characterization, field-effect behavior, electronic transport properties, magnetotransport, integer and fractional quantum Hall effects, mechanical properties, transistors, optoelectronics, graphene-based sensors, and biosensors. This approach attempts to highlight both the means by which the current understanding of graphene has come about and some tools for future contributions.

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Experimental Review of Graphene

In recent years, two-dimensional (2D) materials, including graphene and inorganic graphene analogs (IGAs), have been the subject of intensive studies due to their novel chemical and physical properties. With apparent high surface-to-volume ratio, 2D materials are promising electrode candidates for lithium ion batteries (LIBs). Compared with three-dimensional bulk crystals, 2D materials have superior structural characteristics, and thus can exhibit higher specific capacity and better high-rate stability. In particular, composites consisting of graphene and IGAs could have enhanced electrochemical performances due to the specific synergic effects, which open up new frontiers in fundamental science and technology. Although the explorations of using IGAs for lithium storage have begun very recently, a timely overview in this field is necessary for developing improved electrode candidates. In this feature article, we summarize the ongoing efforts and studies from both experimental and theoretical communities on developing graphene and IGAs as LIB electrodes. Compared with graphene, we put more emphasis on IGAs, such as transition metal oxides, dichalcogenides, and MXenes, and illustrate the significant advantages of IGAs as electrodes. We also show that due to the effective synergic interactions between graphene and IGAs, their composites step further to achieve reversible high-capacity LIBs. Finally, we discuss the problems and limitations for the practical application of 2D materials to LIBs.

Graphene, inorganic graphene analogs and their composites for lithium ion batteries

This work reports a green and facile approach to the synthesis of graphene nanosheets through the zinc reduction of a graphene oxide precursor in alkaline media. Compared to the chemical reduction of GO by using hydrazine or its derivations, the present route is operationally easy and environmentally friendly. Moreover, the reduction degree of GO in the present condition is much higher than that in either Zn or alkaline solutions alone, indicating a cooperative mechanism, and the as-prepared graphene exhibits a good stability in solution. This simple method shows promising applications in the bulk-quantity production of graphene and graphene-based materials.

A facile green strategy for rapid reduction of graphene oxide by metallic zinc

Synthesis of graphene on silicon carbide substrates at low temperature

The atomic arrangement and bonding characteristics of void-free 3C-SiC/Si(100) grown by the modified four-step method are presented. Without the diffusion step, Si-C bonds are partially formed in the as-carburized layer on Si(100). The ratio of C-C bonds to Si-C bonds is about 7:3, which can be lowered to about 1:9 after the diffusion step at 1350°C for 5 min or at 1300°C for 7 min according to C 1s core level spectra. The residual C-C bonds cannot be removed, which is associated with an irregular atomic arrangement (amorphous) located either at the 3C-SiC/Si(100) interface or at the intersection of twin boundaries in the 3C-SiC buffer layer based on the lattice image taken by transmission electron microscope. The diffusion step helps the formation of Si-C bonds more completely and results in a SiC buffer layer of high quality formed on Si(100) before the growth step. However, twins and stacking faults still appear in the 3C-SiC buffer layer after the diffusion step. The formation mechanism of the 3C-SiC buffer layer is proposed and discussed.

https://ir.nctu.edu.tw:443/bitstream/11536/6180/1/000274321900094.pdf

Crystal Quality of 3C-SiC Influenced by the Diffusion Step in the Modified Four-Step Method

https://ir.nctu.edu.tw:443/bitstream/11536/32313/1/000280541400020.pdf

Growth of 3C-SiC on si(111) using the four-step non-cooling process

A method of fabricating a silicon carbide (SiC) layer is disclosed, which comprises steps: (S1) heating a silicon-based substrate at a temperature of X ° C.; (S2) carburizating the silicon-based substrate with a first hydrocarbon-containing gas at a temperature of Y ° C. to form a carbide layer on the silicon-based substrate; (S3) annealing the silicon-based substrate with the carbide layer thereon at a temperature of Z ° C.; and (S4) forming a silicon carbide layer on the carbide layer with a second hydrocarbon-containing gas and a silicon-containing gas at a temperature of W ° C.; wherein, X is 800 to 1200; Y is 1100 to 1400; Z is 1200 to 1500; W is 1300 to 1550; and X<Y≦Z≦W. In the method of the present invention, since no cooling steps between respective steps are required, the full process time can be reduced and the cost is lowered because no energy consumption occurs for the cooling and the re-heating steps.

Method of fabricating silicon carbide (SiC) layer

A void free 3C-SiC film grown on Si(100) can be achieved by low pressure chemical vapor deposition using the modified four-step method. The diffusion step plays an important role to enhance the quality of the 3C-SiC buffer layer on Si(100). X-ray photoelectron spectroscopy was used to characterize the bonding characteristics of the 3C-SiC buffer layer of about 10 nm thick. The Si-C bonds are partially formed on the as-carburized Si(100) before the diffusion step. The ratio of C-C to Si-C bonds on the as-carburized Si(100) is about 7:3, which can be lowered to about 1:9 after the diffusion step at 1350 oC for 5 min or at 1300 oC for 7 min. According to XPS data and Fick’s second law, the diffusivity of Si across the 3C-SiC interlayer are determined to be 2.2×10-16 cm2/s and 3.13×10-16 cm2/s at 1300°C and 1350°C, respectively. The derived activation energy is 1.6 eV for the diffusion of Si atoms in the 3C-SiC buffer layer.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1946427400001810

Wei-Yu Chen

Papers

Synthesis of graphene on silicon carbide substrates at low temperature

Crystal Quality of 3C-SiC Influenced by the Diffusion Step in the Modified Four-Step Method

Growth of 3C-SiC on si(111) using the four-step non-cooling process

Method of fabricating silicon carbide (SiC) layer

Diffusivity of Si in the 3C-SiC buffer layer on Si(100) by X-ray photoelectron spectroscopy