Research

Jump to: Review

11 pages, 1074 KiB

Open AccessArticle

Study of Microwave Heating Effect in the Behaviour of Graphene as Second Phase in Ceramic Composites

by Rut Benavente, María Dolores Salvador, Alba Centeno, Beatriz Alonso, Amaia Zurutuza and Amparo Borrell

Materials 2020, 13(5), 1119; https://doi.org/10.3390/ma13051119 - 03 Mar 2020

Cited by 9 | Viewed by 2294

Abstract

The choice of the right material is essential in microwave processing. The carbon materials are good microwave absorbers, which allows them to be transformed by microwave heating into new carbon materials with adapted properties, capable of heating other materials indirectly. In this paper, [...] Read more.

The choice of the right material is essential in microwave processing. The carbon materials are good microwave absorbers, which allows them to be transformed by microwave heating into new carbon materials with adapted properties, capable of heating other materials indirectly. In this paper, the microwave heating of graphene as reinforcement of the lithium aluminosilicate (LAS) ceramics has been explored. LAS ceramics have a near-zero coefficient of thermal expansion and exhibit an effective and efficient heating by microwave. Nevertheless, we have found that the graphene did not show any significant response to the microwave radiation and, hence, the interaction as mechanical reinforcement with the LAS material is harmful. The possible benefits of graphene materials to microwave technology are widely known; however, the mechanism involved in the interaction of microwave radiation with ceramic-graphene composites with high dielectric loss factors has not been addressed earlier. Full article

(This article belongs to the Special Issue Graphene Oxide: Synthesis, Reduction, and Frontier Applications)

► Show Figures

Figure 1

12 pages, 2985 KiB

Open AccessFeature PaperArticle

Effect of Deposition Parameters on Electrochemical Properties of Polypyrrole-Graphene Oxide Films

by Alina Iuliana Pruna, Nelly Ma. Rosas-Laverde and David Busquets Mataix

Materials 2020, 13(3), 624; https://doi.org/10.3390/ma13030624 - 31 Jan 2020

Cited by 17 | Viewed by 2421

Abstract

Graphene oxide (GO)-modified polypyrrole (PPy) coatings were obtained by electrochemical methods in the presence of the anionic surfactant, sodium dodecyl sulfate (SDS). The structure, morphology, and electrochemical properties of the coatings were assessed by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron [...] Read more.

Graphene oxide (GO)-modified polypyrrole (PPy) coatings were obtained by electrochemical methods in the presence of the anionic surfactant, sodium dodecyl sulfate (SDS). The structure, morphology, and electrochemical properties of the coatings were assessed by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM) and cyclic voltammetry at varying scan rates, respectively. The properties of the obtained coatings were analyzed with the GO and PPy loadings and electrodeposition mode. The hybrid coatings obtained galvanostatically showed a coarser appearance than those deposited by cyclic voltammetry CV mode and improved performance, respectively, which was further enhanced by GO and PPy loading. The capacitance enhancement can be attributed to the SDS surfactant that well dispersed the GO sheets, thus allowing the use of lower GO content for improved contribution, while the choice of suitable electrodeposition parameters is highly important for improving the applicability of GO-modified PPy coatings in energy storage applications. Full article

(This article belongs to the Special Issue Graphene Oxide: Synthesis, Reduction, and Frontier Applications)

► Show Figures

Figure 1

19 pages, 3945 KiB

Open AccessArticle

Graphene Oxyhydride Catalysts in View of Spin Radical Chemistry

by Elena F. Sheka

Materials 2020, 13(3), 565; https://doi.org/10.3390/ma13030565 - 24 Jan 2020

Cited by 5 | Viewed by 2102

Abstract

This article discusses carbocatalysis that are provided with amorphous carbons. The discussion is conducted from the standpoint of the spin chemistry of graphene molecules, in the framework of which the amorphous carbocatalysts are a conglomerate of graphene-oxynitrothiohydride stable radicals presenting the basic structure [...] Read more.

This article discusses carbocatalysis that are provided with amorphous carbons. The discussion is conducted from the standpoint of the spin chemistry of graphene molecules, in the framework of which the amorphous carbocatalysts are a conglomerate of graphene-oxynitrothiohydride stable radicals presenting the basic structure units (BSUs) of the species. The chemical activity of the BSUs atoms is reliably determined computationally, which allows mapping the distribution of active sites in these molecular catalysts. The presented maps reliably show the BSUs radicalization provided with carbon atoms only, the nonterminated edge part of which presents a set of active sites. Spin mapping of carbocatalysts active sites is suggested as the first step towards the spin carbocatalysis of the species. Full article

(This article belongs to the Special Issue Graphene Oxide: Synthesis, Reduction, and Frontier Applications)

► Show Figures

Figure 1

13 pages, 4154 KiB

Open AccessArticle

Graphene Oxide-Assisted Morphology and Structure of Electrodeposited ZnO Nanostructures

by N. Ma. Rosas-Laverde, A. Pruna, D. Busquets-Mataix and D. Pullini

Materials 2020, 13(2), 365; https://doi.org/10.3390/ma13020365 - 13 Jan 2020

Cited by 11 | Viewed by 2843

Abstract

In this paper, ZnO electrodeposition was studied with the presence of graphene oxide (GO) exploited as a possible structure-directing agent. The effect of deposition potential and duration on the morphology and structure of ZnO was analyzed. The morphology and structure of the hybrids [...] Read more.

In this paper, ZnO electrodeposition was studied with the presence of graphene oxide (GO) exploited as a possible structure-directing agent. The effect of deposition potential and duration on the morphology and structure of ZnO was analyzed. The morphology and structure of the hybrids was analyzed by Raman spectroscopy, X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The Raman results indicate a successful modification of ZnO with GO sheets and a hybridization threshold of 10 mg L⁻¹ by the evolution of the defect related band of ZnO at 580 cm⁻¹. The morphology results show that a low GO content only slightly influences the morphology and orientation of ZnO nanostructures while a high content as 10 mg L⁻¹ changes the morphology in nanoplates and growth orientation to lateral. The results show that while GO participated in the deposition reaction, it has a two-fold role, also by structure-controlling ZnO, indicating that the approach is valid for the use of GO as a structure-directing agent for the fabrication of ZnO nanostructures by electrodeposition with varying morphologies and orientations. Full article

(This article belongs to the Special Issue Graphene Oxide: Synthesis, Reduction, and Frontier Applications)

► Show Figures

Figure 1

14 pages, 1994 KiB

Open AccessArticle

Graphene Oxide and Graphene Reinforced PMMA Bone Cements: Evaluation of Thermal Properties and Biocompatibility

by E. Paz, Y. Ballesteros, J. Abenojar, J.C. del Real and N.J. Dunne

Materials 2019, 12(19), 3146; https://doi.org/10.3390/ma12193146 - 26 Sep 2019

Cited by 34 | Viewed by 3227

Abstract

The incorporation of well-dispersed graphene oxide (GO) and graphene (G) has been demonstrated as a promising solution to improve the mechanical performance of polymethyl methacrylate (PMMA) bone cements in an attempt to enhance the long-term survival of the cemented orthopaedic implants. However, to [...] Read more.

The incorporation of well-dispersed graphene oxide (GO) and graphene (G) has been demonstrated as a promising solution to improve the mechanical performance of polymethyl methacrylate (PMMA) bone cements in an attempt to enhance the long-term survival of the cemented orthopaedic implants. However, to move forward with the clinical application of graphene-based PMMA bone cements, it is necessary to ensure the incorporation of graphene-based powders do not negatively affect other fundamental properties (e.g., thermal properties and biocompatibility), which may compromise the clinical success of the implant. In this study, the effect of incorporating GO and G on thermal properties, biocompatibility, and antimicrobial activity of PMMA bone cement was investigated. Differential scanning calorimetry studies demonstrated that the extent of the polymerisation reaction, heat generation, thermal conductivity, or glass transition temperature were not significantly (p > 0.05) affected by the addition of the GO or G powders. The cell viability showed no significant difference (p > 0.05) in viability when MC3-T3 cells were exposed to the surface of G- or GO-PMMA bone cements in comparison to the control. In conclusion, this study demonstrated the incorporation of GO or G powder did not significantly influence the thermal properties or biocompatibility of PMMA bone cements, potentially allowing its clinical progression. Full article

(This article belongs to the Special Issue Graphene Oxide: Synthesis, Reduction, and Frontier Applications)

► Show Figures

Figure 1

13 pages, 4193 KiB

Open AccessArticle

Synthesis and Characterization of Chitosan/Reduced Graphene Oxide Hybrid Composites

by Karolina Kosowska, Patrycja Domalik-Pyzik, Małgorzata Krok-Borkowicz and Jan Chłopek

Materials 2019, 12(13), 2077; https://doi.org/10.3390/ma12132077 - 28 Jun 2019

Cited by 31 | Viewed by 3944

Abstract

Graphene family materials (GFM) are currently considered to be one of the most interesting nanomaterials with a wide range of application. They can also be used as modifiers of polymer matrices to develop composite materials with favorable properties. In this study, hybrid nanocomposites [...] Read more.

Graphene family materials (GFM) are currently considered to be one of the most interesting nanomaterials with a wide range of application. They can also be used as modifiers of polymer matrices to develop composite materials with favorable properties. In this study, hybrid nanocomposites based on chitosan (CS) and reduced graphene oxide (rGO) were fabricated for potential use in bone tissue engineering. CS/rGO hydrogels were prepared by simultaneous reduction and composite formation in acetic acid or lactic acid and crosslinked with a natural agent—tannic acid (TAc). A broad spectrum of research methods was applied in order to thoroughly characterize both the components and the composite systems, i.e., X-ray Photoelectron Spectroscopy, X-ray Diffractometry, Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy, Scanning Electron Microscopy, ninhydrin assay, mechanical testing, in vitro degradation and bioactivity study, wettability, and, finally, cytocompatibility. The composites formed through the self-assembly of CS chains and exfoliated rGO sheets. Obtained results allowed also to conclude that the type of solvent used impacts the polymer structure and its ability to interact with rGO sheets and the mechanical properties of the composites. Both rGO and TAc acted as crosslinkers of the polymer chains. This study shows that the developed materials demonstrate the potential for use in bone tissue engineering. The next step should be their detailed biological examinations. Full article

(This article belongs to the Special Issue Graphene Oxide: Synthesis, Reduction, and Frontier Applications)

► Show Figures

Graphical abstract

14 pages, 2997 KiB

Open AccessArticle

Thermal and Mechanical Interfacial Behaviors of Graphene Oxide-Reinforced Epoxy Composites Cured by Thermal Latent Catalyst

by Shahina Riaz and Soo-Jin Park

Materials 2019, 12(8), 1354; https://doi.org/10.3390/ma12081354 - 25 Apr 2019

Cited by 32 | Viewed by 3239

Abstract

A series of composites was prepared from a diglycidyl ether of bisphenol A (DGEBA) with different graphene filler contents to improve their mechanical performance and thermal stability. Graphene oxide (GO) and GO modified with hexamethylene tetraamine (HMTA) were selected as reinforcing agents. As [...] Read more.

A series of composites was prepared from a diglycidyl ether of bisphenol A (DGEBA) with different graphene filler contents to improve their mechanical performance and thermal stability. Graphene oxide (GO) and GO modified with hexamethylene tetraamine (HMTA) were selected as reinforcing agents. As a latent cationic initiator and curing agent, N-benzylepyrizinium hexafluoroantimonate (N-BPH) was used. The effect of fillers and their contents on the mechanical properties and thermal stability of the composites were studied. Fracture toughness improved by 23% and 40%, and fracture energy was enhanced by 1.94- and 2.27-fold, for the composites containing 0.04 wt.% GO and HMTA-GO, respectively. The gradual increase in fracture toughness at higher filler contents was attributed to both crack deflection and pinning mechanisms. Maximum thermal stability in the composites was achieved by using up to 0.1 wt.% graphene fillers. Full article

(This article belongs to the Special Issue Graphene Oxide: Synthesis, Reduction, and Frontier Applications)

► Show Figures

Figure 1

13 pages, 2989 KiB

Open AccessArticle

A Nanocomposite Based on Reduced Graphene and Gold Nanoparticles for Highly Sensitive Electrochemical Detection of Pseudomonas aeruginosa through Its Virulence Factors

by Islem Gandouzi, Mihaela Tertis, Andreea Cernat, Dalila Saidane-Mosbahi, Aranka Ilea and Cecilia Cristea

Materials 2019, 12(7), 1180; https://doi.org/10.3390/ma12071180 - 11 Apr 2019

Cited by 20 | Viewed by 3960

Abstract

Pyoverdine is a fluorescent siderophore produced by Pseudomonas aeruginosa that can be considered as a detectable marker in nosocomial infections. The presence of pyoverdine in water can be directly linked to the presence of the P. aeruginosa, thus being a nontoxic and [...] Read more.

Pyoverdine is a fluorescent siderophore produced by Pseudomonas aeruginosa that can be considered as a detectable marker in nosocomial infections. The presence of pyoverdine in water can be directly linked to the presence of the P. aeruginosa, thus being a nontoxic and low-cost marker for the detection of biological contamination. A novel platform was developed and applied for the electrochemical selective and sensitive detection of pyoverdine, based on a graphene/graphite-modified screen-printed electrode (SPE) that was electrochemically reduced and decorated with gold nanoparticles (NPs). The optimized sensor presenting higher sensitivity towards pyoverdine was successfully applied for its detection in real samples (serum, saliva, and tap water), in the presence of various interfering species. The excellent analytical performances underline the premises for an early diagnosis kit of bacterial infections based on electrochemical sensors. Full article

(This article belongs to the Special Issue Graphene Oxide: Synthesis, Reduction, and Frontier Applications)

► Show Figures

Figure 1

8 pages, 1548 KiB

Open AccessArticle

Release of Cationic Drugs from Charcoal

by Chiara Di Ruocco, Maria Rosaria Acocella and Gaetano Guerra

Materials 2019, 12(4), 683; https://doi.org/10.3390/ma12040683 - 25 Feb 2019

Cited by 2 | Viewed by 3405

Abstract

The goal of this research is to improve preparation of charcoal adducts in a manner suitable for cationic drug release, possibly using an eco-friendly procedure. Charcoal, widely commercialized for human ingestion, is oxidized by hydrogen peroxide in mild conditions. Adducts of a cationic [...] Read more.

The goal of this research is to improve preparation of charcoal adducts in a manner suitable for cationic drug release, possibly using an eco-friendly procedure. Charcoal, widely commercialized for human ingestion, is oxidized by hydrogen peroxide in mild conditions. Adducts of a cationic drug (lidocaine hydrochloride, a medication used as local anesthetic) with charcoal are prepared after basification of charcoal and characterized mainly by elemental analysis, wide-angle X-ray diffraction, infrared spectroscopy and thermogravimetry. The drug in the prepared adducts is present in amount close to 30% by weight and can be readily released to both neutral and acidic aqueous solutions. Cation release, as studied by UV spectra of aqueous solutions, is faster in acidic solutions and is faster than for adducts with graphite oxide, which can be prepared only in harsh conditions. Full article

(This article belongs to the Special Issue Graphene Oxide: Synthesis, Reduction, and Frontier Applications)

► Show Figures

Figure 1

Review

Jump to: Research

23 pages, 9485 KiB

Open AccessReview

Graphene Oxide and Its Inorganic Composites: Fabrication and Electrorheological Response

by Yu Zhen Dong, Joo Nyeon Kim and Hyoung Jin Choi

Materials 2019, 12(13), 2185; https://doi.org/10.3390/ma12132185 - 07 Jul 2019

Cited by 17 | Viewed by 4176

Abstract

Composite particles associated with graphene oxide (GO) and inorganic materials provide the synergistic properties of an appropriate electrical conductivity of GO with the good dielectric characteristics of inorganic materials, making them attractive candidates for electrorheological (ER) materials. This review paper focuses on the [...] Read more.

Composite particles associated with graphene oxide (GO) and inorganic materials provide the synergistic properties of an appropriate electrical conductivity of GO with the good dielectric characteristics of inorganic materials, making them attractive candidates for electrorheological (ER) materials. This review paper focuses on the fabrication mechanisms of GO/inorganic composites and their ER response when suspended in a non-conducting medium, including steady shear flow curves, dynamic yield stress, On-Off tests, and dynamic oscillation analysis. Furthermore, the morphologies of these composites, dielectric properties, and sedimentation of the ER fluids are covered. Full article

(This article belongs to the Special Issue Graphene Oxide: Synthesis, Reduction, and Frontier Applications)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Graphene Oxide: Synthesis, Reduction, and Frontier Applications

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Published Papers (10 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI