Research

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13 pages, 4302 KiB

Open AccessArticle

Porous Characteristics of Three-Dimensional Disordered Graphene Networks

by YongChao Wang, YinBo Zhu and HengAn Wu

Crystals 2021, 11(2), 127; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11020127 - 28 Jan 2021

Cited by 14 | Viewed by 2646

The porous characteristics of disordered carbons are critical factors to their performance on hydrogen storage and electrochemical capacitors. Even though the porous information can be estimated indirectly by gas adsorption experiments, it is still hard to directly characterize the porous morphology considering the [...] Read more.

The porous characteristics of disordered carbons are critical factors to their performance on hydrogen storage and electrochemical capacitors. Even though the porous information can be estimated indirectly by gas adsorption experiments, it is still hard to directly characterize the porous morphology considering the complex 3D connectivity. To this end, we construct full-atom disordered graphene networks (DGNs) by mimicking the chlorination process of carbide-derived carbons using annealing-MD simulations, which could model the structure of disordered carbons at the atomic scale. The porous characteristics, including pore volume, pore size distribution (PSD), and specific surface area (SSA), were then computed from the coordinates of carbon atoms. From the evolution of structural features, pores grow dramatically during the formation of polyaromatic fragments and sequent disordered framework. Then structure is further graphitized while the PSD shows little change. For the obtained DGNs, the porosity, pore size, and SSA increase with decreasing density. Furthermore, SSA tends to saturate in the low-density range. The DGNs annealed at low temperatures exhibit larger SSA than high-temperature DGNs because of the abundant free edges. Full article

(This article belongs to the Special Issue Graphene-Based Nanocomposites and Manufacturing)

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13 pages, 2228 KiB

Open AccessArticle

Multiple Equilibria and Buckling of Functionally Graded Graphene Nanoplatelet-Reinforced Composite Arches with Pinned-Fixed End

by Zhicheng Yang, Jiamian Xu, Hanwen Lu, Jiangen Lv, Airong Liu and Jiyang Fu

Crystals 2020, 10(11), 1003; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10111003 - 05 Nov 2020

Cited by 12 | Viewed by 1599

Abstract

This paper presents an analytical study on the multiple equilibria and buckling of pinned-fixed functionally graded graphene nanoplatelet-reinforced composite (FG-GPLRC) arches under central point load. It is assumed that graphene nanoplatelets (GPLs) in each GPLRC layer are uniformly distributed and randomly oriented with [...] Read more.

This paper presents an analytical study on the multiple equilibria and buckling of pinned-fixed functionally graded graphene nanoplatelet-reinforced composite (FG-GPLRC) arches under central point load. It is assumed that graphene nanoplatelets (GPLs) in each GPLRC layer are uniformly distributed and randomly oriented with its concentration varying layer-wise along the thickness direction. The Halpin–Tsai micromechanics-based model is used to estimate the effective elastic modulus of GPLRC. The non-linear equilibrium path and buckling load of the pinned-fixed FG-GPLRC arch are subsequently derived by employing the principle of virtual work. The effects of GPLs distribution, weight fraction, size and geometry on the buckling load are examined comprehensively. It is found that the buckling performances of FG-GPLRC arches can be significantly improved by using GPLs as reinforcing nanofillers. It is also found that the non-linear equilibrium path of the pinned-fixed FG-GPLRC arch have multiple limit points and non-linear equilibrium branches when the arch is with a special geometric parameter. Full article

(This article belongs to the Special Issue Graphene-Based Nanocomposites and Manufacturing)

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6 pages, 180 KiB

Open AccessArticle

The Future of Carbon: An Update on Graphene’s Dermal, Inhalation, and Gene Toxicity

by Nima Moghimian and Soroush Nazarpour

Crystals 2020, 10(9), 718; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst10090718 - 19 Aug 2020

Cited by 17 | Viewed by 5563

Abstract

Recent studies on gene, inhalation and dermal toxicity of few-layer graphene have revealed much lower health risk than expected. This could pave the way for graphene as a young member of the nanocarbons family to become the “heir presumptive” to the long-reigning carbon [...] Read more.

Recent studies on gene, inhalation and dermal toxicity of few-layer graphene have revealed much lower health risk than expected. This could pave the way for graphene as a young member of the nanocarbons family to become the “heir presumptive” to the long-reigning carbon black. Full article

(This article belongs to the Special Issue Graphene-Based Nanocomposites and Manufacturing)

Review

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32 pages, 9200 KiB

Open AccessReview

An Overview of Hierarchical Design of Textile-Based Sensor in Wearable Electronics

by Songmei Wu

Crystals 2022, 12(4), 555; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040555 - 15 Apr 2022

Cited by 5 | Viewed by 2899

Abstract

Smart textiles have recently aroused tremendous interests over the world because of their broad applications in wearable electronics, such as human healthcare, human motion detection, and intelligent robotics. Sensors are the primary components of wearable and flexible electronics, which convert various signals and [...] Read more.

Smart textiles have recently aroused tremendous interests over the world because of their broad applications in wearable electronics, such as human healthcare, human motion detection, and intelligent robotics. Sensors are the primary components of wearable and flexible electronics, which convert various signals and external stimuli into electrical signals. While traditional electronic sensors based on rigid silicon wafers can hardly conformably attach on the human body, textile materials including fabrics, yarns, and fibers afford promising alternatives due to their characteristics including light weight, flexibility, and breathability. Of fundamental importance are the needs for fabrics simultaneously having high electrical and mechanical performance. This article focused on the hierarchical design of the textile-based flexible sensor from a structure point of view. We first reviewed the selection of newly developed functional materials for textile-based sensors, including metals, conductive polymers, carbon nanomaterials, and other two-dimensional (2D) materials. Then, the hierarchical structure design principles on different levels from microscale to macroscale were discussed in detail. Special emphasis was placed on the microstructure control of fibers, configurational engineering of yarn, and pattern design of fabrics. Finally, the remaining challenges toward industrialization and commercialization that exist to date were presented. Full article

(This article belongs to the Special Issue Graphene-Based Nanocomposites and Manufacturing)

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27 pages, 5841 KiB

Open AccessReview

Recent Progress in Flexible Graphene-Based Composite Fiber Electrodes for Supercapacitors

by Songmei Wu

Crystals 2021, 11(12), 1484; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11121484 - 30 Nov 2021

Cited by 6 | Viewed by 2579

Abstract

Graphene has shown the world its fascinating properties, including high specific surface area, high conductivity, and extraordinary mechanical properties, which enable graphene to be a competent candidate for electrode materials. However, some challenges remain in the real applications of graphene-based electrodes, such as [...] Read more.

Graphene has shown the world its fascinating properties, including high specific surface area, high conductivity, and extraordinary mechanical properties, which enable graphene to be a competent candidate for electrode materials. However, some challenges remain in the real applications of graphene-based electrodes, such as continuous preparation of graphene fibers with highly ordered graphene sheets as well as strong interlayer interactions. The combination of graphene with other materials or functional guests hence appears as a more promising pathway via post-treatment and in situ hybridism to produce composite fibers. This article firstly provides a full account of the classification of graphene-based composite fiber electrodes, including carbon allotropy, conductive polymer, metal oxide and other two-dimensional (2D) materials. The preparation methods of graphene-based composite fibers are then discussed in detail. The context further demonstrates the performance optimization of graphene-based composite fiber electrodes, involving microstructure design and surface modification, followed by the elaboration of the application of graphene-based composite fiber electrodes in supercapacitors. Finally, we present the remaining challenges that exist to date in order to provide meaningful guidelines in the development process and prospects of graphene-based composite fiber electrodes. Full article

(This article belongs to the Special Issue Graphene-Based Nanocomposites and Manufacturing)

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18 pages, 1197 KiB

Open AccessReview

Preparation, Characterization of Graphitic Carbon Nitride Photo-Catalytic Nanocomposites and Their Application in Wastewater Remediation: A Review

by Caifang Li, Xianliang Wu, Junyue Shan, Jing Liu and Xianfei Huang

Crystals 2021, 11(7), 723; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11070723 - 23 Jun 2021

Cited by 20 | Viewed by 3534

Abstract

Energy crisis and environmental pollution are the major problems of human survival and development. Photocatalytic technology can effectively use solar energy and is prospective to solve the above-mentioned problems. Carbon nitride is a two-dimensional polymer material with a graphite-like structure. It has good [...] Read more.

Energy crisis and environmental pollution are the major problems of human survival and development. Photocatalytic technology can effectively use solar energy and is prospective to solve the above-mentioned problems. Carbon nitride is a two-dimensional polymer material with a graphite-like structure. It has good physical and chemical stabilities, unique chemical and electronic energy band structures, and is widely used in the field of photocatalysis. Graphitic carbon nitride has a conjugated large π bond structure, which is easier to be modified with other compounds. thereby the surface area and visible light absorption range of carbon nitride-based photocatalytic composites can be insignificantly increased, and interface electron transmission and corresponding photogenerated carriers separation of streams are simultaneously promoted. Therefore, the present study systematically introduced the basic catalytic principles, preparation and modification methods, characterization and calculation simulation of carbon nitride-based photocatalytic composite materials, and their application in wastewater treatment. We also summarized their application in wastewater treatment with the aid of artificial intelligence tools. This review summarized the frontier technology and future development prospects of graphite phase carbon nitride photocatalytic composites, which provide a theoretical reference for wastewater purification. Full article

(This article belongs to the Special Issue Graphene-Based Nanocomposites and Manufacturing)

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26 pages, 2351 KiB

Open AccessReview

Advances in the Applications of Graphene-Based Nanocomposites in Clean Energy Materials

by Yiqiu Xiang, Ling Xin, Jiwei Hu, Caifang Li, Jimei Qi, Yu Hou and Xionghui Wei

Crystals 2021, 11(1), 47; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11010047 - 07 Jan 2021

Cited by 19 | Viewed by 5418

Abstract

Extensive use of fossil fuels can lead to energy depletion and serious environmental pollution. Therefore, it is necessary to solve these problems by developing clean energy. Graphene materials own the advantages of high electrocatalytic activity, high conductivity, excellent mechanical strength, strong flexibility, large [...] Read more.

Extensive use of fossil fuels can lead to energy depletion and serious environmental pollution. Therefore, it is necessary to solve these problems by developing clean energy. Graphene materials own the advantages of high electrocatalytic activity, high conductivity, excellent mechanical strength, strong flexibility, large specific surface area and light weight, thus giving the potential to store electric charge, ions or hydrogen. Graphene-based nanocomposites have become new research hotspots in the field of energy storage and conversion, such as in fuel cells, lithium-ion batteries, solar cells and thermoelectric conversion. Graphene as a catalyst carrier of hydrogen fuel cells has been further modified to obtain higher and more uniform metal dispersion, hence improving the electrocatalyst activity. Moreover, it can complement the network of electroactive materials to buffer the change of electrode volume and prevent the breakage and aggregation of electrode materials, and graphene oxide is also used as a cheap and sustainable proton exchange membrane. In lithium-ion batteries, substituting heteroatoms for carbon atoms in graphene composite electrodes can produce defects on the graphitized surface which have a good reversible specific capacity and increased energy and power densities. In solar cells, the performance of the interface and junction is enhanced by using a few layers of graphene-based composites and more electron-hole pairs are collected; therefore, the conversion efficiency is increased. Graphene has a high Seebeck coefficient, and therefore, it is a potential thermoelectric material. In this paper, we review the latest progress in the synthesis, characterization, evaluation and properties of graphene-based composites and their practical applications in fuel cells, lithium-ion batteries, solar cells and thermoelectric conversion. Full article

(This article belongs to the Special Issue Graphene-Based Nanocomposites and Manufacturing)

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22 pages, 2415 KiB

Open AccessReview

A Review on Graphene’s Light Stabilizing Effects for Reduced Photodegradation of Polymers

by Samira Karimi, Emna Helal, Giovanna Gutierrez, Nima Moghimian, Milad Madinehei, Eric David, Mazen Samara and Nicole Demarquette

Crystals 2021, 11(1), 3; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11010003 - 22 Dec 2020

Cited by 28 | Viewed by 5821

Abstract

Graphene, the newest member of the carbon’s family, has proven its efficiency in improving polymers’ resistance against photodegradation, even at low loadings equal to 1 wt% or lower. This protective role involves a multitude of complementary mechanisms associated with graphene’s unique geometry and [...] Read more.

Graphene, the newest member of the carbon’s family, has proven its efficiency in improving polymers’ resistance against photodegradation, even at low loadings equal to 1 wt% or lower. This protective role involves a multitude of complementary mechanisms associated with graphene’s unique geometry and chemistry. In this review, these mechanisms, taking place during both the initiation and propagation steps of photodegradation, are discussed concerning graphene and graphene derivatives, i.e., graphene oxide (GO) and reduced graphene oxide (rGO). In particular, graphene displays important UV absorption, free radical scavenging, and quenching capabilities thanks to the abundant π-bonds and sp² carbon sites in its hexagonal lattice structure. The free radical scavenging effect is also partially linked with functional hydroxyl groups on the surface. However, the sp² sites remain the predominant player, which makes graphene’s antioxidant effect potentially stronger than rGO and GO. Besides, UV screening and oxygen barriers are active protective mechanisms attributed to graphene’s high surface area and 2D geometry. Moreover, the way that graphene, as a nucleating agent, can improve the photostability of polymers, have been explored as well. These include the potential effect of graphene on increasing polymer’s glass transition temperature and crystallinity. Full article

(This article belongs to the Special Issue Graphene-Based Nanocomposites and Manufacturing)

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