Thanks to their remarkable mechanical, electrical, thermal, and barrier properties, graphene-based nanocomposites have been a hot area of research in the past decade. Because of their simple top-down ...synthesis, graphene oxide (GO) and reduced graphene oxide (rGO) have opened new possibilities for gas barrier, membrane separation, and stimuli-response characteristics in nanocomposites. Herein, we review the synthesis techniques most commonly used to produce these graphene derivatives, discuss how synthesis affects their key material properties, and highlight some examples of nanocomposites with unique and impressive properties. We specifically highlight their performances in separation applications, stimuli-responsive materials, anti-corrosion coatings, and energy storage. Finally, we discuss the outlook and remaining challenges in the field of practical industrial-scale production and use of graphene-derivative-based polymer nanocomposites. Keywords: Graphene oxide, Reduced graphene oxide, Graphene quantum dots polymer, Nanocomposites, Synthesis, Properties of graphene and graphene oxide, Applications
•Graphene oxide (FL-GOc) and reduced graphene oxide (FL-RGOc): XRD, TEM, XPS, REELS.•FL-GOc: stacking nanostructure—22×6nm (DxH), 0.9nm layers separation (XRD).•FL-RGOc: stacking nanostructure—8×1nm ...(DxH), 0.4nm layers separation (XRD).•Reduction: oxygen group degradation, decreasing distance between graphene layers.•Number of graphene layers in stacking nanostructure: 6–7 (FL-GOc), 2–3 (FL-RGOc).
The commercial and synthesised few-layer graphene oxide, prepared using oxidation reactions, and few-layer reduced graphene oxide samples were structurally and chemically investigated by the X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron spectroscopy methods, i.e. X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS).
The commercial graphene oxide (FL-GOc) shows a stacking nanostructure of about 22×6nm average diameter by height with the distance of 0.9nm between 6-7 graphene layers, whereas the respective reduced graphene oxide (FL-RGOc)—about 8×1nm average diameter by height stacking nanostructure with the distance of 0.4nm between 2-3 graphene layers (XRD). The REELS results are consistent with those by the XRD indicating 8 (FL-GOc) and 4 layers (FL-RGOc). In graphene oxide and reduced graphene oxide prepared from the graphite the REELS indicates 8–11 and 7–10 layers. All graphene oxide samples show the C/O ratio of 2.1–2.3, 26.5–32.1 at% of C sp3 bonds and high content of functional oxygen groups (hydroxyl—COH, epoxy—COC, carbonyl—CO, carboxyl—COOH, water) (XPS). Reduction increases the C/O ratio to 2.8–10.3, decreases C sp3 content to 11.4–20.3 at% and also the content of COC and CO groups, accompanied by increasing content of COH and COOH groups. Formation of additional amount of water due to functional oxygen group reduction leads to layer delamination. Removing of functional oxygen groups and water molecules results in decreasing the distance between the graphene layers.
•Characteristics and characterization of graphene are discussed.•Graphene synthesis methods are evaluated via cost, environment and social impacts.•Oxidative exfoliation-reduction, LPE and CVD ...potentially can be commercialized.•More work is needed to overcome environmental concerns and the high graphene cost.
Graphene and its derivatives have gained significant attention of late due to their remarkable physicochemical properties. This review focuses firstly on the synthesis methods of graphene and its derivatives along with their attributes and characterization techniques. This is followed by a discussion of the potential industrial implementation of the synthesis routes. The potential industrial implementation of the graphene synthesis methods are reviewed using the key criteria of cost, process condition, yield, scalability, product quality and environmental impact. The literature data supported that synthesis routes such as oxidative exfoliation-reduction, liquid-phase exfoliation and chemical vapor deposition have the potential to be commercialized due to their ability to produce large amount of high quality graphene. Further development is necessary to overcome barriers such as environmental concerns and the high graphene cost.
Display omitted
Chlorpheniramine is a pharmaceutical widely used and found in water environments. Besides hormone disruption and adverse environmental effects, chlorpheniramine forms carcinogenic nitrosamines during ...disinfection. We have demonstrated previously the efficient adsorption of chlorpheniramine from aqueous solution onto graphene oxide-magnetite composite (GO-Fe3O4). The present study focused on the elimination of chlorpheniramine and the formation of nitrosamine byproducts during reaction with H2O2 over GO-Fe3O4 catalyst. The effects of the morphology of GO-Fe3O4 in terms of iron fraction, pH, concentrations of H2O2 and organic matters on chlorpheniramine removal in the GO-Fe3O4-H2O2 system were investigated. Chlorpheniramine was efficiently removed at pH 9 when GO-Fe3O4 had a higher micropore volume and surface area. Kinetics study showed that both oxidation (k = 5.1(±0.2) × 10−3 (mg g−1)−1 min−1) and adsorption reactions (k = 2.7(±0.1) × 10−3 (mg g−1)−1 min−1) fitted well with the second-order kinetics model. The adsorption sites on the GO-Fe3O4 surface could be different from those involved during catalytic oxidation. Chlorpheniramine removal decreased by 44.9% in the 5th cycle without regeneration due to the structural fracture of GO-Fe3O4. A tentative pathway of chlorpheniramine degradation and nitrosamine formation by GO-Fe3O4-H2O2 was proposed. GO-Fe3O4 was an adsorbent and effective catalyst in chlorpheniramine degradation by H2O2 that exhibited limited nitrosamine formation at moderate reaction time.
Display omitted
•Chlorpheniramine degradation was effective by H2O2 over GO-Fe3O4 catalyst.•The formation of nitrosamine byproducts was identified.•Morphology of GO-Fe3O4, pH, H2O2 and NOM affected chlorpheniramine degradation.•Catalytic oxidation changed the adsorption sites on GO-Fe3O4 surface.•A degradation pathway of chlorpheniramine by the GO-Fe3O4-H2O2 system was proposed.
Graphene and graphene-based materials have a high potential, especially in energy storage technology. Thanks to the three-dimensional (3D) structures developed with this material, their importance in ...the production and application of energy storage devices has increased. Studies on supercapacitor applications of graphene-based aerogels have begun to arouse interest in recent years. In this study, recent studies on aerogel supercapacitors, in which researchers have shown great interest, have been compiled and collected. In this study, production methods and properties of graphene oxide, properties and production of aerogels, production and applications of graphene/graphene oxide aerogels are discussed. In this way, the data is presented and discussed in an organized way for the researchers who study or who want to study in this field.
Display omitted
Graphene nanoparticles (GNPs) have become increasingly attractive nanomaterials in their application in various biosensing platforms. Several benefits from the size reduction distinguish them from ...graphene (Gr) and graphene (GO), resulting from the electron confinement to smaller surfaces and increased edge-plane ratio. This allows for higher electrochemical activity due to the increased edge density and introduction of bandgap related photoluminescence even in GNPs that do not contain oxygen functional groups. The oxygenated counterparts, although less electrochemically active, are endowed with improved dispersibility and stability. Few aspects will be discussed in the presented review: a) the advantages and disadvantages of Gr and GO, regarding their electrical and optical properties; b) the properties of GNPs and their oxygen-containing analogs (GONPs) gained by the size reduction and quantum confinement effect; c) a clear distinction of GNPs/GONPs as nanoscale forms compared to the microscale Gr/GO; d) presenting a definition of GNPs and proper classification of the special forms of GNPs, graphene nanoribbons (GNRs) and graphene quantum dots (GQDs); e) summary of the proposed GNP biosensors will be provided, as classified into three main sections: GNPs, GNRs, and GQDs, with separate subsections for their oxygenated equivalents.
Copper ions in wastewater pose a significant threat to human and ecological safety. Therefore, preparing macroscopic adsorbents with reusable and high adsorption performance is paramount. This paper ...used graphene oxide as the adsorbent and chitosan as the thickener. Additionally, a silane coupling agent was employed to enhance the acid resistance of chitosan, and amino-modification of graphene oxide was performed. Macroscopic adsorbents with high adsorption capacity were fabricated using 3D printing technology. The results show that all five proportions of inks exhibit good printability. Dissolution experiments revealed that all materials maintained structural integrity after 180 days across pH values. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) confirmed the successful preparation of the materials. Adsorption experiments showed that the best performing material ratio was 8 wt% graphene oxide and 7 wt% chitosan. Adsorption kinetics and isothermal adsorption experiments demonstrated that the adsorption process occurred via monolayer chemisorption. The adsorption process was attributed to strong electrostatic forces, van der Waals forces, and nitrogen/oxygen-containing functional group coordination. Cycling experiments showed that the material retained good adsorption performance after 6 cycles, suggesting its potential for practical heavy metal treatment applications.
Display omitted
•Graphene oxide/chitosan adsorbent (GO/CS) was 3D printed.•GO/CS has good acid resistance via cross-linked.•Amino-modified GO/CS enhanced the removal ability of Cu2+.
Harnessing the exceptional physical properties of graphene often requires its dispersion into aqueous or organic media. Dispersion must be achieved at a concentration and stability appropriate to the ...final application. However, the strong interaction between graphene sheets means it disperses poorly in all but a few high boiling organic solvents. This review presents an overview of graphene dispersion applications and a discussion of dispersion strategies: in particular the effect of shear, solvent and chemical modification on the dispersion of graphene (including graphene oxide and reduced graphene oxide). These techniques are discussed in the context of manufacturing and commercialisation.
Graphene, a single, one-atom-thick sheet of carbon atoms arranged in a honeycomb lattice and the two-dimensional building block for carbon materials, has attracted great interest for a wide range of ...applications. Due to its superior properties such as thermo-electric conduction, surface area and mechanical strength, graphene materials have inspired huge interest in sensing of various chemical species. In this timely review, we discuss the recent advancement in the field of graphene based gas sensors with emphasis on the use of modified graphene materials. Further, insights of theoretical and experimental aspects associated with such systems are also discussed with significance on the sensitivity and selectivity of graphene towards various gas molecules. The first section introduces graphene, its synthesis methods and its physico-chemical properties. The second part focuses on the theoretical approaches that discuss the structural improvisations of graphene for its effective use as gas sensing materials. The third section discusses the applications of pristine and modified graphene materials in gas sensing applications. Various graphene modification methods are discussed including using dopants and defects, decoration with metal/metal oxide nanoparticles, and functionalization with polymers. Finally, a discussion on the future challenges and perspectives of this enticing field of graphene sensors for gas detection is provided.
Spillage of effluents containing high concentration levels of pesticides into water has been considered as one of the serious environmental problems. In this study Fe3O4/reduced graphene oxide (rGO) ...nanocomposite has been efficiently utilized for the adsorption of five harmful pesticides namely ametryn, prometryn, simazine, simeton and atrazine in an aqueous medium. Electrostatic interaction between the pesticides and Fe3O4/rGO nanocomposite was analyzed by the zeta potential analysis, which is strongly related to the adsorption capacity of the adsorbent. The kinetics parameters of adsorption followed the pseudo second-order linear model. The adsorption isotherm studies show that, the maximum adsorption capacity of 54.8 mg g−1 is achieved at pH 5 and it was enhanced in the presence of different ions (Mg2+, Ca2+, Na+ and SO42) and maximum (63.7 mg g−1) for ametryn adsorption was found in seawater medium. Thermodynamic parameter shows that, the adsorption process is physisorption and spontaneity in nature. The mechanism of the adsorption process was established by the DRIFT spectroscopy analysis. Efficient adsorption (93.61%) of pesticides was observed due to electrostatic, hydrophobic and π–π interactions of composite towards the heterocyclic conjugation of pesticide molecules. Further, Fe3O4/rGO nanocomposite was easily and rapidly separated from an aqueous medium using the external magnet for reuse and 88.66% adsorption efficiency was observed up to seven cycles.
Display omitted
•A feasible and eco-friendly route for the removal of five triazine pesticides.•Magnetic Fe3O4/rGO shows efficient triazine pesticides removal property.•Specific ion effect plays an important role in pesticide adsorption onto Fe3O4/rGO.•The reusability and magnetic reparability of Fe3O4/rGO is added advantage.
PDF
