Till now, several innovative methods have been developed for the synthesis of graphene materials including mechanical exfoliation, epitaxial growth by chemical vapor deposition, chemical reduction of ...graphite oxide, liquid-phase exfoliation, arc discharge of graphite,
in situ
electron beam irradiation, epitaxial growth on SiC, thermal fusion, laser reduction of polymers sheets and unzipping of carbon nanotubes
etc.
Generally large scale graphene nanosheets are reliably synthesized utilizing other forms of graphene-based novel materials, including graphene oxide (GO), exfoliated graphite oxide (by thermal and microwave), and reduced graphene oxide. The degree of GO reduction and number of graphene layers are minimized mainly by applying two approaches
via
chemical or thermal treatments. The promising and excellent properties together with the ease of processability and chemical functionalization makes graphene based materials especially GO, ideal candidates for incorporation into a variety of advanced functional materials. Chemical functionalization of graphene can be easily achieved, by the introduction of various functional groups. These functional groups help to control and manipulate the graphene surfaces and help to tune the properties of the resulting hybrid materials. Importantly, graphene and its derivatives GO, have been explored in a wide range of applications, such as energy generation/storage, optical devices, electronic and photonic devices, drug delivery, clean energy, and chemical/bio sensors. In this review article, we have incorporated a general introduction of GO, its synthesis, reduction and some selected frontier applications.
In this review article, we describe a general introduction to GO, its synthesis, reduction and some selected frontier applications. Its low cost and potential for mass production make GO a promising building block for functional hybrid materials.
Carbon nanomaterials have huge potential in the field of energy and environmental applications. However, a wide range of greener and environment friendly synthesis methods utilizing natural, ...renewable, cheaper waste materials has to be developed. This will lead to the reduction of green house gases, exploitation of toxic materials and helps in the development of sustainable technologies. In this review, the details progress made in the last ten years concerning the synthesis of new one dimensional (carbon nanotubes CNT, carbon nanofiber) and two dimensional (graphene) carbon based materials using natural precursors and waste materials is summarized. The aim of this review paper is to provide a comprehensive scientific progress of synthesis of graphene and carbon nanotubes using natural precursor and waste materials for the future perspective. This paper also concludes with a brief discussion on the impact of natural precursor for the graphene and CNTs for environment, its toxicological effects and its future prospects in this rapidly emerging field. Natural precursors and waste carbon containing products are emerging as a new class of materials that have efficiency to produce graphene and CNTs. The various synthesis processes of graphene, CNTs and carbon dots has been reported using several natural hydrocarbon precursors (turpentine oil, eucalyptus oil, palm oil, neem oil, sunflower oil, castor oil, biodiesel, tea-tree extract, honey, milk, sugar, butter, egg etc.). Also, some research groups have used foods wastes (cookie and chocolate), vegetation wastes (woods, leaf, grass, fruit wastes), animal/bird/insect wastes (bone and cow dung, dog feces, chicken feather) and agro waste (sugarcane bagasse) for the synthesis of graphene and CNTs. Research on natural hydrocarbon precursors and wastage materials has increased in recent years as they promise to produce better and high quality of graphene and CNTs in large quantities. The fascinating aspect of this research area is that it guides the use of natural hydrocarbons to explore the possibilities of improving graphene stability and robustness suitable for different type of applications.
The importance of graphene and its derivatives for “clean energy” applications became apparent over the last few years due to their exceptional characteristics, especially regarding electrical, ...thermal and chemical properties. In this review article we examine the recent progress and some of the challenges in the syntheses and modification of graphene-based materials, including energy storage applications as electrodes in Li-ion batteries (LIBs). Various synthesis routes have been used for obtaining graphene using different kinds of carbon sources (graphite, non-graphitic carbon and carbon-containing materials). The most popular processing methods include epitaxial growth, liquid phase chemical/electrochemical exfoliation, mechanical exfoliation, chemical vapor deposition and laser-assisted synthesis. Taking the reduction approach, chemical, thermal, microwave and laser reduction methods have been applied to prepare graphene from graphene oxide/graphite oxide. Recent research has shown that graphene derivatives and hybrids/ nanocomposites using metal oxides/mixed metal oxides and metal sulfides/mixed metal sulphides can have a profound impact on the performance of energy storage devices. Closing the text, we speculate on the future prospects for the application of graphene and its derivatives in energy storage devices. We expect that this review article will help in generating new insights for further development and practical applications of graphene-based materials.
Supercapacitors are energy storage devices with unique characteristics, and together with batteries have generated a significant research effort, with various types of electrode materials having been ...developed over the last few years. Current trends for this application have been gradually shifting towards pseudocapacitive/battery-like materials. When compared to electric double-layer capacitors, pseudocapacitive/battery-type materials have a decisive advantage, since they are usually able to deliver improved energy density. Furthermore, these materials can undergo reversible electrochemical reactions within a very short period of time without compromising their high charge storage capacity. In this article, we systematically survey the current state of the art regarding the fabrication and electrochemical performance of the most promising classes of pseudocapacitive/battery-type electrode materials for supercapacitors. The text covers metal oxides, mixed metal oxides, conducting polymers, and MXenes. Closing the article, some of the outstanding problems for increasing the performance of SCs are discussed, and future research directions are suggested.
Systematic survey on the fabrication and electrochemical performance of the most promising classes of pseudocapacitive/battery-type electrode materials for supercapacitors.
Laser-based approaches for graphene synthesis, reduction, modification, cutting and micro-patterning have been developed and applied to the fabrication of various electronic devices. These ...laser-based techniques exhibit several advantages over alternative methods: low temperature, shorter reaction times, environmentally friendly, energy saving, catalyst free growth on insulating substrates, high productivity, better reproducibility, scalability, excellent control over experimental parameters. Given the importance of the subject, in the last few years a remarkable increase in the number of scientific articles has occurred in this area. Direct fabrication of graphene patterns for micro-supercapacitors, flexible electrodes, field-effect-transistors, and sensors are some of the examples. Direct laser writing enables local graphene synthesis and fabrication of graphene patterns on graphene oxide films. It can be used to achieve band gap modulation, removal of surface functionalities, conductivity enhancement, exfoliation and porous structure formation. The aim of this review is to collect some of the most relevant research efforts published on this important topic, with emphasis in the articles published in the last few years. After an introduction highlighting the main factors affecting the outcome of laser-materials interactions, devices built using direct laser writing (DLW) on graphene oxide/graphene films and the experimental conditions used for their fabrication are summarized. Some of the expected directions for promising future research in this area are briefly discussed.
The significance of graphene and its two-dimensional (2D) analogous inorganic layered materials especially as hexagonal boron nitride (h-BN) and molybdenum disulphide (MoS
2
) for “clean energy” ...applications became apparent over the last few years due to their extraordinary properties. In this review article we study the current progress and selected challenges in the syntheses of graphene, h-BN and MoS
2
including energy storage applications as supercapacitors and batteries. Various substrates/catalysts (metals/insulator/semiconducting) have been used to obtain graphene, h-BN and MoS
2
using different kinds of precursors. The most widespread methods for synthesis of graphene, h-BN and MoS
2
layers are chemical vapor deposition (CVD), plasma-enhanced CVD, hydro/solvothermal methods, liquid phase exfoliation, physical methods etc. Current research has shown that graphene, h-BN and MoS
2
layered materials modified with metal oxide can have an insightful influence on the performance of energy storage devices as supercapacitors and batteries. This review article also contains the discussion on the opportunities and perspectives of these materials (graphene, h-BN and MoS
2
) in the energy storage fields. We expect that this written review article including recent research on energy storage will help in generating new insights for further development and practical applications of graphene, h-BN and MoS
2
layers based materials.
Here we report the electrochemical performance of a interesting three-dimensional (3D) structures comprised of zero-dimensional (0D) cobalt oxide nanobeads, one-dimensional (1D) carbon nanotubes and ...two-dimensional (2D) graphene, stacked hierarchically. We have synthesized 3D self-assembled hierarchical nanostructure comprised of cobalt oxide nanobeads (Co-nb), carbon nanotubes (CNTs), and graphene nanosheets (GNSs) for high-performance supercapacitor electrode application. This 3D self-assembled hierarchical nanostructure Co3O4 nanobeads–CNTs–GNSs (3D:Co-nb@CG) is grown at a large scale (gram) through simple, facile, and ultrafast microwave irradiation (MWI). In 3D:Co-nb@CG nanostructure, Co3O4 nanobeads are attached to the CNT surfaces grown on GNSs. Our ultrafast, one-step approach not only renders simultaneous growth of cobalt oxide and CNTs on graphene nanosheets but also institutes the intrinsic dispersion of carbon nanotubes and cobalt oxide within a highly conductive scaffold. The 3D:Co-nb@CG electrode shows better electrochemical performance with a maximum specific capacitance of 600 F/g at the charge/discharge current density of 0.7A/g in KOH electrolyte, which is 1.56 times higher than that of Co3O4-decorated graphene (Co-np@G) nanostructure. This electrode also shows a long cyclic life, excellent rate capability, and high specific capacitance. It also shows high stability after few cycles (550 cycles) and exhibits high capacitance retention behavior. It was observed that the supercapacitor retained 94.5% of its initial capacitance even after 5000 cycles, indicating its excellent cyclic stability. The synergistic effect of the 3D:Co-nb@CG appears to contribute to the enhanced electrochemical performances.
Currently, nanomaterials are considered to be the backbone of modern civilization. Especially in the energy sector, nanomaterials (mainly, carbon- and metal oxide/hydroxide-based nanomaterials) have ...contributed significantly. Among the various green approaches for the synthesis of these nanomaterials, the microwave-assisted approach has attracted significant research interest worldwide. In this context, it is noteworthy to mention that because of their enhanced surface area, high conducting nature, and excellent electrical and electrochemical properties, carbon nanomaterials are being extensively utilized as efficient electrode materials for both supercapacitors and secondary batteries. In this review article, we briefly demonstrate the characteristics of microwave-synthesized nanomaterials for next-generation energy storage devices. Starting with the basics of microwave heating, herein, we illustrate the past and present status of microwave chemistry for energy-related applications, and finally present a brief outlook and concluding remarks. We hope that this review article will positively convey new insights for the microwave synthesis of nanomaterials for energy storage applications.
Microwave-assisted synthesis of carbon nanomaterials, metal oxides/hydroxides and their composites for energy storage applications.
This review article provides an introduction to microwave heating, focusing on its intrinsic advantages, and presents an overview of the latest research on microwave processed graphene-based ...electrode materials for supercapacitors.
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The various methods for microwave processing of materials exhibit numerous advantages, such as short processing times, high yield, expanded reaction conditions, high reproducibility, and high purity of products. Microwave-assisted synthesis strategies have been widely adopted for the preparation of high-performance graphene-based materials for supercapacitor electrodes. Metal oxides, mixed metal oxides, metal hydroxides, layered double hydroxides, carbon nanotubes and conducting polymers are some of the main materials which have been added to graphene derivatives for advanced composite/hybrid electrodes. This review article first provides a brief introduction and an overview of microwave heating and its advantages for processing graphene-based electrode materials. After that, a systematic survey of recently published research on microwave irradiation-assisted processing is presented, focusing on: (i) transformation of graphite/ graphite oxide into graphene/graphene oxide by exfoliation and reduction; (ii) formation of graphene derivatives in various liquid and gaseous media; (iii) modification of graphene derivatives with various metal oxides/hydroxides, carbon nanotubes, and conducting polymers for use in supercapacitors. Major challenges and future perspectives for microwave-assisted processing of graphene-based materials for cutting-edge supercapacitor electrode applications are also summarized in the conclusion.
The demand for electromagnetic interference (EMI) shielding has increased strongly in the last few years, owing to the fast technological developments in the electronics industry. In order to meet ...these markedly increased demands, many new layer-structured materials (as well as other structures with various morphologies) are being investigated to replace conventionally used metal sheets for the purpose of EMI shielding. Carbon-based nanostructures and their composites are used for EMI protection due to their low weight, cost-effectiveness, and good thermal/electrical properties. Polymers are also low density materials, with the added benefits of low cost and easy processing. Composites combining various polymers with different types of conducting carbon fillers have been proposed as EM wave absorbers. MXene-based 2D layered materials have also received tremendous attention for application in EMI shielding. In this review article, we have systematically summarized the recent research on materials designed for microwave/radio wave absorption and EMI shielding. The text covers carbon-based nanostructured materials, various kinds of polymers, layered inorganic materials and their composite hybrids. The review is concluded with a brief discussion of the perspectives and outstanding challenges for future EMI shielding applications of carbon, polymers and MXene-based materials.
The main classes of materials used for EMI shielding and possible attenuation mechanisms for EM waves incident on a slab of EMI shielding material. Display omitted
