Nanomaterials

Editorial

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2 pages, 149 KiB

Open AccessEditorial

Electronic and Thermal Properties of Graphene

by Kyong Yop Rhee

Nanomaterials 2020, 10(5), 926; https://doi.org/10.3390/nano10050926 - 11 May 2020

Cited by 17 | Viewed by 2583

Abstract

Recently, the development of nanotechnology has bloomed in numerous industries [...] Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

Research

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10 pages, 22018 KiB

Open AccessArticle

Transparent Electrothermal Heaters Based on Vertically-Oriented Graphene Glass Hybrid Materials

by Lingzhi Cui, Kejian Cui, Haina Ci, Kaiqiang Zheng, Huanhuan Xie, Xuan Gao, Yanfeng Zhang and Zhongfan Liu

Nanomaterials 2019, 9(4), 558; https://doi.org/10.3390/nano9040558 - 6 Apr 2019

Cited by 9 | Viewed by 3609

Abstract

Transparent heating devices are widely used in daily life-related applications that can be achieved by various heating materials with suitable resistances. Herein, high-performance vertically-oriented graphene (VG) films are directly grown on soda-lime glass by a radio-frequency (rf) plasma-enhanced chemical vapor deposition (PECVD) method, [...] Read more.

Transparent heating devices are widely used in daily life-related applications that can be achieved by various heating materials with suitable resistances. Herein, high-performance vertically-oriented graphene (VG) films are directly grown on soda-lime glass by a radio-frequency (rf) plasma-enhanced chemical vapor deposition (PECVD) method, giving reasonable resistances for electrothermal heating. The optical and electrical properties of VG films are found to be tunable by optimizing the growth parameters such as growth time, carrier gas flow, etc. The electrothermal performances of the derived materials with different resistances are thus studied systematically. Specifically, the VG film on glass with a transmittance of ~73% at 550 nm and a sheet resistance of ~3.9 KΩ/□ is fabricated into a heating device, presenting a saturated temperature up to 55 °C by applying 80 V for 3 min. The VG film on the glass at a transmittance of ~43% and a sheet resistance of 0.76 KΩ/□ exhibits a highly steady temperature increase up to ~108 °C with a maximum heating rate of ~2.6 °C/s under a voltage of 60 V. Briefly, the tunable sheet resistance, good adhesion of VG to the growth substrate, relative high heating efficiency, and large heating temperature range make VG films on glass decent candidates for electrothermal related applications in defrosting and defogging devices. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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13 pages, 5886 KiB

Open AccessArticle

Facile Preparation and Characterization of Carbon Fibers with Core-Shell Structure from Graphene-Dispersed Isotropic Pitch Compounds

by Dong Hun Lee, Yong-Hwan Choi, Kyong Yop Rhee, Kap Seung Yang and Byung-Joo Kim

Nanomaterials 2019, 9(4), 521; https://doi.org/10.3390/nano9040521 - 3 Apr 2019

Cited by 6 | Viewed by 3202

Abstract

In this study, isotropic pitch-based carbon fibers were prepared from a mixture of petroleum residue and graphene nanoplatelets with different contents. The softening point and synthetic yield of synthesized isotropic pitches were analyzed and compared to characterize the nature of the pitches. The [...] Read more.

In this study, isotropic pitch-based carbon fibers were prepared from a mixture of petroleum residue and graphene nanoplatelets with different contents. The softening point and synthetic yield of synthesized isotropic pitches were analyzed and compared to characterize the nature of the pitches. The surface and thermal characteristics of the fibers were observed using scanning electron microscopy and thermogravimetric analysis (TGA), respectively. From the results, it was observed that the prepared carbon fibers had an interesting core-shell structure. In the TGA analysis with air, the carbon fiber having 0.1 wt.% of graphene showed a higher residue yield than that of the sample having 1.0 wt.% of graphene. This result can be explained due to the graphene being placed on the surface region of the carbon fibers and directly helping to increase the surface area of the carbon fibers, resulting in rapid oxidation due to the enhanced contact area with oxygen. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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12 pages, 5673 KiB

Open AccessArticle

Effect of Varying the Ratio of Carbon Black to Vapor-Grown Carbon Fibers in the Separator on the Performance of Li–S Batteries

by Hearin Jo, Jeonghun Oh, Yong Min Lee and Myung-Hyun Ryou

Nanomaterials 2019, 9(3), 436; https://doi.org/10.3390/nano9030436 - 15 Mar 2019

Cited by 6 | Viewed by 5034

Abstract

Lithium–sulfur (Li–S) batteries are expected to be very useful for next-generation transportation and grid storage because of their high energy density and low cost. However, their low active material utilization and poor cycle life limit their practical application. The use of a carbon-coated [...] Read more.

Lithium–sulfur (Li–S) batteries are expected to be very useful for next-generation transportation and grid storage because of their high energy density and low cost. However, their low active material utilization and poor cycle life limit their practical application. The use of a carbon-coated separator in these batteries serves to inhibit the migration of the lithium polysulfide intermediate and increases the recyclability. We report the extent to which the electrochemical performance of Li–S battery systems depends on the characteristics of the carbon coating of the separator. Carbon-coated separators containing different ratios of carbon black (Super-P) and vapor-grown carbon fibers (VGCFs) were prepared and evaluated in Li–S batteries. The results showed that larger amounts of Super-P on the carbon-coated separator enhanced the electrochemical performance of Li–S batteries; for instance, the pure Super-P coating exhibited the highest discharge capacity (602.1 mAh g⁻¹ at 150 cycles) with a Coulombic efficiency exceeding 95%. Furthermore, the separators with the pure Super-P coating had a smaller pore structure, and hence, limited polysulfide migration, compared to separators containing Super-P/VGCF mixtures. These results indicate that it is necessary to control the porosity of the porous membrane to control the movement of the lithium polysulfide. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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19 pages, 6290 KiB

Open AccessArticle

Graphene Nanoplatelet-Reinforced Poly(vinylidene fluoride)/High Density Polyethylene Blend-Based Nanocomposites with Enhanced Thermal and Electrical Properties

by Kartik Behera, Mithilesh Yadav, Fang-Chyou Chiu and Kyong Yop Rhee

Nanomaterials 2019, 9(3), 361; https://doi.org/10.3390/nano9030361 - 4 Mar 2019

Cited by 35 | Viewed by 3872

Abstract

In this study, a graphene nanoplatelet (GNP) was used as a reinforcing filler to prepare poly(vinylidene fluoride) (PVDF)/high density polyethylene (HDPE) blend-based nanocomposites through a melt mixing method. Scanning electron microscopy confirmed that the GNP was mainly distributed within the PVDF matrix phase. [...] Read more.

In this study, a graphene nanoplatelet (GNP) was used as a reinforcing filler to prepare poly(vinylidene fluoride) (PVDF)/high density polyethylene (HDPE) blend-based nanocomposites through a melt mixing method. Scanning electron microscopy confirmed that the GNP was mainly distributed within the PVDF matrix phase. X-ray diffraction analysis showed that PVDF and HDPE retained their crystal structure in the blend and composites. Thermogravimetric analysis showed that the addition of GNP enhanced the thermal stability of the blend, which was more evident in a nitrogen environment than in an air environment. Differential scanning calorimetry results showed that GNP facilitated the nucleation of PVDF and HDPE in the composites upon crystallization. The activation energy for non-isothermal crystallization of PVDF increased with increasing GNP loading in the composites. The Avrami n values ranged from 1.9–3.8 for isothermal crystallization of PVDF in different samples. The Young’s and flexural moduli of the blend improved by more than 20% at 2 phr GNP loading in the composites. The measured rheological properties confirmed the formation of a pseudo-network structure of GNP-PVDF in the composites. The electrical resistivity of the blend reduced by three orders at a 3-phr GNP loading. The PVDF/HDPE blend and composites showed interesting application prospects for electromechanical devices and capacitors. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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12 pages, 4094 KiB

Open AccessArticle

Facile Synthesis of SnO₂ Aerogel/Reduced Graphene Oxide Nanocomposites via in Situ Annealing for the Photocatalytic Degradation of Methyl Orange

by Taehee Kim, Vinayak G. Parale, Hae-Noo-Ree Jung, Younghun Kim, Zied Driss, Dorra Driss, Abdallah Bouabidi, Souhir Euchy and Hyung-Ho Park

Nanomaterials 2019, 9(3), 358; https://doi.org/10.3390/nano9030358 - 4 Mar 2019

Cited by 56 | Viewed by 5228

Abstract

SnO₂ aerogel/reduced graphene oxide (rGO) nanocomposites were synthesized using the sol–gel method. A homogeneous dispersion of graphene oxide (GO) flakes in a tin precursor solution was captured in a three-dimensional network SnO₂ aerogel matrix and successively underwent supercritical alcohol drying followed [...] Read more.

SnO₂ aerogel/reduced graphene oxide (rGO) nanocomposites were synthesized using the sol–gel method. A homogeneous dispersion of graphene oxide (GO) flakes in a tin precursor solution was captured in a three-dimensional network SnO₂ aerogel matrix and successively underwent supercritical alcohol drying followed by the in situ thermal reduction of GO, resulting in SnO₂ aerogel/rGO nanocomposites. The chemical interaction between aerogel matrix and GO functional groups was confirmed by a peak shift in the Fourier transform infrared spectra and a change in the optical bandgap of the diffuse reflectance spectra. The role of rGO in 3D aerogel structure was studied in terms of photocatalytic activity with detailed mechanism of the enhancement such as electron transfer between the GO and SnO₂. In addition, the photocatalytic activity of these nanocomposites in the methyl orange degradation varied depending on the amount of rGO loading in the SnO₂ aerogel matrix; an appropriate amount of rGO was required for the highest enhancement in the photocatalytic activity of the SnO₂ aerogel. The proposed nanocomposites could be a useful solution against water pollutants. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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8 pages, 3862 KiB

Open AccessArticle

Introducing Well-Defined Nanowrinkles in CVD Grown Graphene

by Tim Verhagen, Barbara Pacakova, Martin Kalbac and Jana Vejpravova

Nanomaterials 2019, 9(3), 353; https://doi.org/10.3390/nano9030353 - 4 Mar 2019

Cited by 3 | Viewed by 3261

Abstract

The control of graphene’s topography at the nanoscale level opens up the possibility to greatly improve the surface functionalization, change the doping level or create nanoscale reservoirs. However, the ability to control the modification of the topography of graphene on a wafer scale [...] Read more.

The control of graphene’s topography at the nanoscale level opens up the possibility to greatly improve the surface functionalization, change the doping level or create nanoscale reservoirs. However, the ability to control the modification of the topography of graphene on a wafer scale is still rather challenging. Here we present an approach to create well-defined nanowrinkles on a wafer scale using nitrocellulose as the polymer to transfer chemical vapor deposition grown graphene from the copper foil to a substrate. During the transfer process, the complex tertiary nitrocellulose structure is imprinted into the graphene area layer. When the graphene layer is put onto a substrate this will result in a well-defined nanowrinkle pattern, which can be subsequently further processed. Using atomic force and Raman microscopy, we characterized the generated nanowrinkles in graphene. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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15 pages, 6819 KiB

Open AccessArticle

Effect of Defects on the Mechanical and Thermal Properties of Graphene

by Maoyuan Li, Tianzhengxiong Deng, Bing Zheng, Yun Zhang, Yonggui Liao and Huamin Zhou

Nanomaterials 2019, 9(3), 347; https://doi.org/10.3390/nano9030347 - 3 Mar 2019

Cited by 76 | Viewed by 5867

Abstract

In this study, the mechanical and thermal properties of graphene were systematically investigated using molecular dynamic simulations. The effects of temperature, strain rate and defect on the mechanical properties, including Young’s modulus, fracture strength and fracture strain, were studied. The results indicate that [...] Read more.

In this study, the mechanical and thermal properties of graphene were systematically investigated using molecular dynamic simulations. The effects of temperature, strain rate and defect on the mechanical properties, including Young’s modulus, fracture strength and fracture strain, were studied. The results indicate that the Young’s modulus, fracture strength and fracture strain of graphene decreased with the increase of temperature, while the fracture strength of graphene along the zigzag direction was more sensitive to the strain rate than that along armchair direction by calculating the strain rate sensitive index. The mechanical properties were significantly reduced with the existence of defect, which was due to more cracks and local stress concentration points. Besides, the thermal conductivity of graphene followed a power law of λ~L^0.28, and decreased monotonously with the increase of defect concentration. Compared with the pristine graphene, the thermal conductivity of defective graphene showed a low temperature-dependent behavior since the phonon scattering caused by defect dominated the thermal properties. In addition, the corresponding underlying mechanisms were analyzed by the stress distribution, fracture structure during the deformation and phonon vibration power spectrum. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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12 pages, 2979 KiB

Open AccessArticle

Origin of Room-Temperature Ferromagnetism in Hydrogenated Epitaxial Graphene on Silicon Carbide

by Mohamed Ridene, Ameneh Najafi and Kees Flipse

Nanomaterials 2019, 9(2), 228; https://doi.org/10.3390/nano9020228 - 8 Feb 2019

Cited by 2 | Viewed by 3761

Abstract

The discovery of room-temperature ferromagnetism of hydrogenated epitaxial graphene on silicon carbide challenges for a fundamental understanding of this long-range phenomenon. Carbon allotropes with their dispersive electron states at the Fermi level and a small spin-orbit coupling are not an obvious candidate for [...] Read more.

The discovery of room-temperature ferromagnetism of hydrogenated epitaxial graphene on silicon carbide challenges for a fundamental understanding of this long-range phenomenon. Carbon allotropes with their dispersive electron states at the Fermi level and a small spin-orbit coupling are not an obvious candidate for ferromagnetism. Here we show that the origin of ferromagnetism in hydrogenated epitaxial graphene with a relatively high Curie temperature (>300 K) lies in the formation of curved specific carbon site regions in the graphene layer, induced by the underlying Si-dangling bonds and by the hydrogen bonding. Hydrogen adsorption is therefore more favourable at only one sublattice site, resulting in a localized state at the Fermi energy that can be attributed to a pseudo-Landau level splitting. This n = 0 level forms a spin-polarized narrow band at the Fermi energy leading to a high Curie temperature and larger magnetic moment can be achieved due to the presence of Si dangling bonds underneath the hydrogenated graphene layer. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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12 pages, 4582 KiB

Open AccessArticle

Thermo-Responsive Graphene Oxide/Poly(Ethyl Ethylene Phosphate) Nanocomposite via Ring Opening Polymerization

by Xue Jiang, Guolin Lu, Xiaoyu Huang, Yu Li, Fangqi Cao, Hong Chen and Wenbin Liu

Nanomaterials 2019, 9(2), 207; https://doi.org/10.3390/nano9020207 - 5 Feb 2019

Cited by 10 | Viewed by 4026

Abstract

An efficient strategy for growing thermo-sensitive polymers from the surface of exfoliated graphene oxide (GO) is reported in this article. GO sheets with hydroxyls and epoxy groups on the surface were first prepared by modified Hummer’s method. Epoxy groups on GO sheets can [...] Read more.

An efficient strategy for growing thermo-sensitive polymers from the surface of exfoliated graphene oxide (GO) is reported in this article. GO sheets with hydroxyls and epoxy groups on the surface were first prepared by modified Hummer’s method. Epoxy groups on GO sheets can be easily modified through ring-opening reactions, involving nucleophilic attack by tris(hydroxymethyl) aminomethane (TRIS). The resulting GO-TRIS sheets became a more versatile precursor for next ring opening polymerization (ROP) of ethyl ethylene phosphate (EEP), leading to GO-TRIS/poly(ethyl ethylene phosphate) (GO-TRIS-PEEP) nanocomposite. The nanocomposite was characterized by ¹H NMR, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential thermal gravity (DTG), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Since hydrophilic PEEP chains make the composite separate into single layers through hydrogen bonding interaction, the dispersity of the functionalized GO sheets in water is significantly improved. Meanwhile, the aqueous dispersion of GO-TRIS-PEEP nanocomposite shows reversible temperature switching self-assembly and disassembly behavior. Such a smart graphene oxide-based hybrid material is promising for applications in the biomedical field. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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11 pages, 1743 KiB

Open AccessArticle

Latent Heat Storage and Thermal Efficacy of Carboxymethyl Cellulose Carbon Foams Containing Ag, Al, Carbon Nanotubes, and Graphene in a Phase Change Material

by Hong Gun Kim, Yong-Sun Kim, Lee Ku Kwac, Hee Jae Shin, Sang Ok Lee, U Sang Lee and Hye Kyoung Shin

Nanomaterials 2019, 9(2), 158; https://doi.org/10.3390/nano9020158 - 28 Jan 2019

Cited by 18 | Viewed by 3710

Abstract

Carbon foam was prepared from carboxymethyl cellulose (CMC) and Ag, Al and carbon nanotubes (CNTs), and graphene was added to the foam individually, to investigate the enhancement effects on the thermal conductivity. In addition, we used the vacuum method to impregnate erythritol of [...] Read more.

Carbon foam was prepared from carboxymethyl cellulose (CMC) and Ag, Al and carbon nanotubes (CNTs), and graphene was added to the foam individually, to investigate the enhancement effects on the thermal conductivity. In addition, we used the vacuum method to impregnate erythritol of the phase change material (PCM) into the carbon foam samples to maximize the latent heat and minimize the latent heat loss during thermal cycling. Carbon foams containing Ag (CF-Ag), Al (CF-Al), CNT (CF-CNT) and graphene (CF-G) showed higher thermal conductivity than the carbon foam without any nano thermal conducting materials (CF). From the variations in temperature with time, erythritol added to CF, CF-Ag, CF-Al, CF-CNT, and CF-G was observed to decrease the time required to reach the phase change temperature when compared with pure erythritol. Among them, erythritol added to CF-G had the fastest phase change temperature, and this was related to the fact that this material had the highest thermal conductivity of the carbon foams used in this study. According to differential scanning calorimetry (DSC) analyses, the materials in which erythritol was added (CF, CF-Ag, CF-Al, CF-CNT, and CF-G) showed lower latent heat values than pure erythritol, as a result of their supplementation with carbon foam. However, the latent heat loss of these supplemented materials was less than that of pure erythritol during thermal cycling tests because of capillary and surface tension forces. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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12 pages, 23231 KiB

Open AccessArticle

An Ultra-High-Energy Density Supercapacitor; Fabrication Based on Thiol-functionalized Graphene Oxide Scrolls

by Janardhanan. R. Rani, Ranjith Thangavel, Se-I Oh, Yun Sung Lee and Jae-Hyung Jang

Nanomaterials 2019, 9(2), 148; https://doi.org/10.3390/nano9020148 - 24 Jan 2019

Cited by 76 | Viewed by 7456

Abstract

Present state-of-the-art graphene-based electrodes for supercapacitors remain far from commercial requirements in terms of high energy density. The realization of high energy supercapacitor electrodes remains challenging, because graphene-based electrode materials are synthesized by the chemical modification of graphene. The modified graphene electrodes have [...] Read more.

Present state-of-the-art graphene-based electrodes for supercapacitors remain far from commercial requirements in terms of high energy density. The realization of high energy supercapacitor electrodes remains challenging, because graphene-based electrode materials are synthesized by the chemical modification of graphene. The modified graphene electrodes have lower electrical conductivity than ideal graphene, and limited electrochemically active surface areas due to restacking, which hinders the access of electrolyte ions, resulting in a low energy density. In order to solve the issue of restacking and low electrical conductivity, we introduce thiol-functionalized, nitrogen-doped, reduced graphene oxide scrolls as the electrode materials for an electric double-layer supercapacitor. The fabricated supercapacitor exhibits a very high energy/power density of 206 Wh/kg (59.74 Wh/L)/496 W/kg at a current density of 0.25 A/g, and a high power/energy density of 32 kW/kg (9.8 kW/L)/9.58 Wh/kg at a current density of 50 A/g; it also operates in a voltage range of 0~4 V with excellent cyclic stability of more than 20,000 cycles. By suitably combining the scroll-based electrode and electrolyte material, this study presents a strategy for electrode design for next-generation energy storage devices with high energy density without compromising the power density. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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10 pages, 2087 KiB

Open AccessArticle

Atomistic Study of Mechanical Behaviors of Carbon Honeycombs

by Huaipeng Wang, Qiang Cao, Qing Peng and Sheng Liu

Nanomaterials 2019, 9(1), 109; https://doi.org/10.3390/nano9010109 - 18 Jan 2019

Cited by 19 | Viewed by 4416

Abstract

With an ultralarge surface-to-volume ratio, a recently synthesized three-dimensional graphene structure, namely, carbon honeycomb, promises important engineering applications. Herein, we have investigated, via molecular dynamics simulations, its mechanical properties, which are inevitable for its integrity and desirable for any feasible implementations. The uniaxial [...] Read more.

With an ultralarge surface-to-volume ratio, a recently synthesized three-dimensional graphene structure, namely, carbon honeycomb, promises important engineering applications. Herein, we have investigated, via molecular dynamics simulations, its mechanical properties, which are inevitable for its integrity and desirable for any feasible implementations. The uniaxial tension and nanoindentation behaviors are numerically examined. Stress–strain curves manifest a transformation of covalent bonds of hinge atoms when they are stretched in the channel direction. The load–displacement curve in nanoindentation simulation implies the hardness and Young’s modulus to be 50.9 GPa and 461±9 GPa, respectively. Our results might be useful for material and device design for carbon honeycomb-based systems. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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9 pages, 2033 KiB

Open AccessArticle

Facile and Green Synthesis of Graphene-Based Conductive Adhesives via Liquid Exfoliation Process

by Jhao-Yi Wu, Yi-Chin Lai, Chien-Liang Chang, Wu-Ching Hung, Hsiao-Min Wu, Ying-Chih Liao, Chia-Hung Huang and Wei-Ren Liu

Nanomaterials 2019, 9(1), 38; https://doi.org/10.3390/nano9010038 - 28 Dec 2018

Cited by 7 | Viewed by 3129

Abstract

In this study, we report a facile and green process to synthesize high-quality and few-layer graphene (FLG) derived from graphite via a liquid exfoliation process. The corresponding characterizations of FLG, such as scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscopy [...] Read more.

In this study, we report a facile and green process to synthesize high-quality and few-layer graphene (FLG) derived from graphite via a liquid exfoliation process. The corresponding characterizations of FLG, such as scanning electron microscopy (SEM), transmission electron microscope (TEM), atomic force microscopy (AFM) and Raman spectroscopy, were carried out. The results of SEM show that the lateral size of as-synthesized FLG is 1–5 μm. The results of TEM and AFM indicate more than 80% of graphene layers is <10 layers. The most surprising thing is that D/G ratio of graphite and FLG are 0.15 and 0.19, respectively. The result of the similar D/G ratio demonstrates that little structural defects were created via the liquid exfoliation process. Electronic conductivity tests and resistance of composite film, in terms of different contents of graphite/polyvinylidene difluoride (PVDF) and FLG/PVDF, were carried out. Dramatically, the FLG/PVDF composite demonstrates superior performance compared to the graphite/PVDF composite at the same ratio. In addition, the post-sintering process plays an important role in improving electronic conductivity by 85%. The composition-optimized FLG/PVDF thin film exhibits 81.9 S·cm⁻¹. These results indicate that the developed FLG/PVDF composite adhesives could be a potential candidate for conductive adhesive applications. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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6 pages, 1633 KiB

Open AccessCommunication

Electrochemical Enantiomer Recognition Based on sp³-to-sp² Converted Regenerative Graphene/Diamond Electrode

by Jingyao Gao, Haoyang Zhang, Chen Ye, Qilong Yuan, Kuan W. A. Chee, Weitao Su, Aimin Yu, Jinhong Yu, Cheng-Te Lin, Dan Dai and Li Fu

Nanomaterials 2018, 8(12), 1050; https://doi.org/10.3390/nano8121050 - 14 Dec 2018

Cited by 12 | Viewed by 3910

Abstract

It is of great significance to distinguish enantiomers due to their different, even completely opposite biological, physiological and pharmacological activities compared to those with different stereochemistry. A sp³-to-sp² converted highly stable and regenerative graphene/diamond electrode (G/D) was proposed as an [...] Read more.

It is of great significance to distinguish enantiomers due to their different, even completely opposite biological, physiological and pharmacological activities compared to those with different stereochemistry. A sp³-to-sp² converted highly stable and regenerative graphene/diamond electrode (G/D) was proposed as an enantiomer recognition platform after a simple β-cyclodextrin (β-CD) drop casting process. The proposed enantiomer recognition sensor has been successfully used for d and l-phenylalanine recognition. In addition, the G/D electrode can be simply regenerated by half-minute sonication due to the strong interfacial bonding between graphene and diamond. Therefore, the proposed G/D electrode showed significant potential as a reusable sensing platform for enantiomer recognition. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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Review

Jump to: Editorial, Research

42 pages, 8117 KiB

Open AccessReview

Recent Advances in Graphene-Based Humidity Sensors

by Chao Lv, Cun Hu, Junhong Luo, Shuai Liu, Yan Qiao, Zhi Zhang, Jiangfeng Song, Yan Shi, Jinguang Cai and Akira Watanabe

Nanomaterials 2019, 9(3), 422; https://doi.org/10.3390/nano9030422 - 12 Mar 2019

Cited by 178 | Viewed by 12104

Abstract

Humidity sensors are a common, but important type of sensors in our daily life and industrial processing. Graphene and graphene-based materials have shown great potential for detecting humidity due to their ultrahigh specific surface areas, extremely high electron mobility at room temperature, and [...] Read more.

Humidity sensors are a common, but important type of sensors in our daily life and industrial processing. Graphene and graphene-based materials have shown great potential for detecting humidity due to their ultrahigh specific surface areas, extremely high electron mobility at room temperature, and low electrical noise due to the quality of its crystal lattice and its very high electrical conductivity. However, there are still no specific reviews on the progresses of graphene-based humidity sensors. This review focuses on the recent advances in graphene-based humidity sensors, starting from an introduction on the preparation and properties of graphene materials and the sensing mechanisms of seven types of commonly studied graphene-based humidity sensors, and mainly summarizes the recent advances in the preparation and performance of humidity sensors based on pristine graphene, graphene oxide, reduced graphene oxide, graphene quantum dots, and a wide variety of graphene based composite materials, including chemical modification, polymer, metal, metal oxide, and other 2D materials. The remaining challenges along with future trends in high-performance graphene-based humidity sensors are also discussed. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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25 pages, 42017 KiB

Open AccessReview

Recent Progress on Graphene-Functionalized Metasurfaces for Tunable Phase and Polarization Control

by Jierong Cheng, Fei Fan and Shengjiang Chang

Nanomaterials 2019, 9(3), 398; https://doi.org/10.3390/nano9030398 - 8 Mar 2019

Cited by 77 | Viewed by 7883

Abstract

The combination of graphene and a metasurface holds great promise for dynamic manipulation of the electromagnetic wave from low terahertz to mid-infrared. The optical response of graphene is significantly enhanced by the highly-localized fields in the meta-atoms, and the characteristics of meta-atoms can [...] Read more.

The combination of graphene and a metasurface holds great promise for dynamic manipulation of the electromagnetic wave from low terahertz to mid-infrared. The optical response of graphene is significantly enhanced by the highly-localized fields in the meta-atoms, and the characteristics of meta-atoms can in turn be modulated in a large dynamic range through electrical doping of graphene. Graphene metasurfaces are initially focused on intensity modulation as modulators and tunable absorbers. In this paper, we review the recent progress of graphene metasurfaces for active control of the phase and the polarization. The related applications involve, but are not limited to lenses with tunable intensity or focal length, dynamic beam scanning, wave plates with tunable frequency, switchable polarizers, and real-time generation of an arbitrary polarization state, all by tuning the gate voltage of graphene. The review is concluded with a discussion of the existing challenges and the personal perspective of future directions. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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33 pages, 27503 KiB

Open AccessReview

Electronic and Thermal Properties of Graphene and Recent Advances in Graphene Based Electronics Applications

by Mingyu Sang, Jongwoon Shin, Kiho Kim and Ki Jun Yu

Nanomaterials 2019, 9(3), 374; https://doi.org/10.3390/nano9030374 - 5 Mar 2019

Cited by 290 | Viewed by 18549

Abstract

Recently, graphene has been extensively researched in fundamental science and engineering fields and has been developed for various electronic applications in emerging technologies owing to its outstanding material properties, including superior electronic, thermal, optical and mechanical properties. Thus, graphene has enabled substantial progress [...] Read more.

Recently, graphene has been extensively researched in fundamental science and engineering fields and has been developed for various electronic applications in emerging technologies owing to its outstanding material properties, including superior electronic, thermal, optical and mechanical properties. Thus, graphene has enabled substantial progress in the development of the current electronic systems. Here, we introduce the most important electronic and thermal properties of graphene, including its high conductivity, quantum Hall effect, Dirac fermions, high Seebeck coefficient and thermoelectric effects. We also present up-to-date graphene-based applications: optical devices, electronic and thermal sensors, and energy management systems. These applications pave the way for advanced biomedical engineering, reliable human therapy, and environmental protection. In this review, we show that the development of graphene suggests substantial improvements in current electronic technologies and applications in healthcare systems. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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18 pages, 3430 KiB

Open AccessReview

Electrical Property of Graphene and Its Application to Electrochemical Biosensing

by Jin-Ho Lee, Soo-Jeong Park and Jeong-Woo Choi

Nanomaterials 2019, 9(2), 297; https://doi.org/10.3390/nano9020297 - 20 Feb 2019

Cited by 106 | Viewed by 11865

Abstract

Graphene, a single atom thick layer of two-dimensional closely packed honeycomb carbon lattice, and its derivatives have attracted much attention in the field of biomedical, due to its unique physicochemical properties. The valuable physicochemical properties, such as high surface area, excellent electrical conductivity, [...] Read more.

Graphene, a single atom thick layer of two-dimensional closely packed honeycomb carbon lattice, and its derivatives have attracted much attention in the field of biomedical, due to its unique physicochemical properties. The valuable physicochemical properties, such as high surface area, excellent electrical conductivity, remarkable biocompatibility and ease of surface functionalization have shown great potentials in the applications of graphene-based bioelectronics devices, including electrochemical biosensors for biomarker analysis. In this review, we will provide a selective overview of recent advances on synthesis methods of graphene and its derivatives, as well as its application to electrochemical biosensor development. We believe the topics discussed here are useful, and able to provide a guideline in the development of novel graphene and on graphene-like 2-dimensional (2D) materials based biosensors in the future. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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29 pages, 12715 KiB

Open AccessReview

The Thermal, Electrical and Thermoelectric Properties of Graphene Nanomaterials

by Jingang Wang, Xijiao Mu and Mengtao Sun

Nanomaterials 2019, 9(2), 218; https://doi.org/10.3390/nano9020218 - 6 Feb 2019

Cited by 87 | Viewed by 9577

Abstract

Graphene, as a typical two-dimensional nanometer material, has shown its unique application potential in electrical characteristics, thermal properties, and thermoelectric properties by virtue of its novel electronic structure. The field of traditional material modification mainly changes or enhances certain properties of materials by [...] Read more.

Graphene, as a typical two-dimensional nanometer material, has shown its unique application potential in electrical characteristics, thermal properties, and thermoelectric properties by virtue of its novel electronic structure. The field of traditional material modification mainly changes or enhances certain properties of materials by mixing a variety of materials (to form a heterostructure) and doping. For graphene as well, this paper specifically discusses the use of traditional modification methods to improve graphene’s electrical and thermoelectrical properties. More deeply, since graphene is an atomic-level thin film material, its shape and edge conformation (zigzag boundary and armchair boundary) have a great impact on performance. Therefore, this paper reviews the graphene modification field in recent years. Through the change in the shape of graphene, the change in the boundary structure configuration, the doping of other atoms, and the formation of a heterostructure, the electrical, thermal, and thermoelectric properties of graphene change, resulting in broader applications in more fields. Through studies of graphene’s electrical, thermal, and thermoelectric properties in recent years, progress has been made not only in experimental testing, but also in theoretical calculation. These aspects of graphene are reviewed in this paper. Full article

(This article belongs to the Special Issue Electronic and Thermal Properties of Graphene)

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