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Optical absorbers based on Tamm plasmon states are known for their simple structure and high operational efficiency. However, these absorbers often have limited absorption channels, and it is challenging to continuously adjust their light absorption rates. Here, we propose a Tamm plasmon state optical absorber composed of a layered stack structure consisting of one-dimensional topological photonic crystals and graphene nano-composite materials. Using the four-by-four transfer matrix method, we investigate the structural relationship of the absorber. Our results reveal that topological interface states (TISs) effectively excite the optical Tamm state (OTS), leading to multiple absorption peaks. This expands the number of absorption channels, with the coupling number of the TIS determining the transmission quality of these channels—a value further adjustable by the period number of the photonic crystals. Tuning the filling factor, refractive index, and thickness of the graphene nano-composite material allows for a wide range of control over the device's absorption rate, from 0 to 1. Additionally, adjusting the defect layer thickness, incident angle, and Fermi energy enables us to control the absorber's operational bandwidth and the switching of its absorption effect. This work presents a new approach to expanding the tunability of optoelectronic devices. [ABSTRACT FROM AUTHOR]

Chemically stable two-dimensional nanostructured graphene with huge surface area, high electrical conductivity and mechanical excellence has gained significant research attention in the past two decades. Its excellent characteristics make graphene one of the important materials in various applications such as environmental and energy storage devices. Graphene no doubt has been a top priority among the carbon nanomaterials owing to its structure and properties. However, the functionalization of graphene leads to various nanocomposites where its properties are tailored to be suited for various applications with more performance, environmental friendliness, efficiency, durability and cost effectiveness. Graphene nanocomposites are said to exhibit more surface area, conductivity, power conversion efficiency and other characteristics in energy devices like supercapacitors. This review was aimed to present some of the applications of graphene-based nanocomposites in energy conversion devices like supercapacitors and Li-ion batteries and some of the environmental applications. It was observed that the performance of supercapacitors was obstructed due to restacking and agglomeration of graphene layers. This was addressed by combining MO (metal oxide) or CP (conducting polymer) with graphene as material for electrodes. Electrodes with CP or MO/graphene composites are summarized. Heterogeneous catalysts were of environmental concern in recent years. In this context, graphene-based nanocomposites gained significance due to expansion in structural diversity. A minimum overview is presented in this paper in terms of structural aspects and properties of GO/rGO-based materials used in supercapacitors and environmental applications like dye removal. Continuous efforts towards synthesis of productive graphene-based nanocomposites might lead to significant output in applications related to environment and energy sectors. [ABSTRACT FROM AUTHOR]

We report new nanocomposites with poly(benzoxazine-co-epoxy) matrix reinforced with 1 wt% graphene. Curabox 24-111, a benzoxazine resin was copolymerised with Epilok 60-566, a mixture of epoxy resins. Copolymerisation was also carried out in the presence of different graphene powders, namely, Nanene-001 and Nanene-002, used as single fillers and as mixture (relative weight ratio 70:30 or 30:70). DSC results showed the addition of either single filler caused a delay in polymerisation and an increase in the exothermic peak temperature of the curing reaction with a related reduction in ΔH Total. compared to the neat copolymer. Copolymerisation showed a 38% reduction and 24% increase in tensile modulus (E) compared to the neat polybenzoxazine and epoxy polymer, with a respective 18% and 30% reduction in tensile strength (TS). Nanocomposites with 0.7wt% Nanene-002 + 0.3 wt% Nanene-001 showed the highest increase of 35% in TS, a 1.6% reduction in E and 36% increase in elongation at break (EB) compared to the neat copolymer matrix. Samples with 1 wt% Nanene-001 showed the largest reduction of 21% in E, a 27% increase in TS and a 45% increase in EB. Additionally, TGA thermographs showed a 22°C increase in the onset of degradation (300°C–322°C) improving the materials thermal stability. [ABSTRACT FROM AUTHOR]

Optical absorbers based on Tamm plasmon states are known for their simple structure and high operational efficiency. However, these absorbers often have limited absorption channels, and it is challenging to continuously adjust their light absorption rates. Here, we propose a Tamm plasmon state optical absorber composed of a layered stack structure consisting of one-dimensional topological photonic crystals and graphene nano-composite materials. Using the four-by-four transfer matrix method, we investigate the structural relationship of the absorber. Our results reveal that topological interface states (TISs) effectively excite the optical Tamm state (OTS), leading to multiple absorption peaks. This expands the number of absorption channels, with the coupling number of the TIS determining the transmission quality of these channels—a value further adjustable by the period number of the photonic crystals. Tuning the filling factor, refractive index, and thickness of the graphene nano-composite material allows for a wide range of control over the device’s absorption rate, from 0 to 1. Additionally, adjusting the defect layer thickness, incident angle, and Fermi energy enables us to control the absorber’s operational bandwidth and the switching of its absorption effect. This work presents a new approach to expanding the tunability of optoelectronic devices.

Chemically stable two-dimensional nanostructured graphene with huge surface area, high electrical conductivity and mechanical excellence has gained significant research attention in the past two decades. Its excellent characteristics make graphene one of the important materials in various applications such as environmental and energy storage devices. Graphene no doubt has been a top priority among the carbon nanomaterials owing to its structure and properties. However, the functionalization of graphene leads to various nanocomposites where its properties are tailored to be suited for various applications with more performance, environmental friendliness, efficiency, durability and cost effectiveness. Graphene nanocomposites are said to exhibit more surface area, conductivity, power conversion efficiency and other characteristics in energy devices like supercapacitors. This review was aimed to present some of the applications of graphene-based nanocomposites in energy conversion devices like supercapacitors and Li-ion batteries and some of the environmental applications. It was observed that the performance of supercapacitors was obstructed due to restacking and agglomeration of graphene layers. This was addressed by combining MO (metal oxide) or CP (conducting polymer) with graphene as material for electrodes. Electrodes with CP or MO/graphene composites are summarized. Heterogeneous catalysts were of environmental concern in recent years. In this context, graphene-based nanocomposites gained significance due to expansion in structural diversity. A minimum overview is presented in this paper in terms of structural aspects and properties of GO/rGO-based materials used in supercapacitors and environmental applications like dye removal. Continuous efforts towards synthesis of productive graphene-based nanocomposites might lead to significant output in applications related to environment and energy sectors.

In this work, chitosan/graphene nanocomposite granules with weight percentages of 0.5%, 1%, 2% and 5% were prepared using a solution method. At first, graphene was oxidized with sulfuric and nitric acid then triethylenetetramine was grafted on graphene surface. Functionalized graphene was characterized by Fourier-transform infrared spectroscopy (FT-IR), Therapeutic Goods Administration (TGA), X-ray energy diffraction spectroscopy (EDX) and Scanning electron microscope (SEM). Results showed functionalization of graphene was successfully accomplished. The thermogravimetric analysis curves showed the pristine, oxidized and functionalized graphenes are stable up to 400, 250, and 300, respectively. The pristine graphenes are more stable than oxidized graphenes and the oxidized graphenes are more stable than functionalized graphenes. The observed stabilized temperature is known to be strongly influenced by the step of the functionalization. The morphology of nanocomposite was monitored by Scanning electron microscope (SEM). The SEM images showed that the porosity was reduced due to presence of nano graphenes. Results showed that the nanocomposite samples have higher potential for ion metals adsorption than that of neat chitosan. The adsorption of nano samples for cadmium was increased around 20% in comparison to neat chitosan. Atomic adsorption spectrometry showed that the optimal adsorption rate of cadmium ion occurs in a solution of 50 ppm with a pH = 7 and a contact time of 2 hours and an adsorbent of 25 mg.

Compared with contemporary electrofusion techniques that use embedded wires for Joule heating, microwave heating may facilitate the joining of thermoplastic polymer components, promising shortened fusion periods, superior heating uniformity, and reduced energy consumption. This study investigates the fabrication of multifunctional polylactide acid (PLA) composites with strong microwave absorption using graphene nanoplatelets (GNP). GNP/PLA nanocomposites were fabricated using a two‐step scalable manufacturing method, that is, solution blending and hot compression molding. The GNP content of the composites ranged from 0% to 8% by weight. The samples were characterized for dielectric permittivity, heat capacity, and electrical and thermal conductivity. Thermal imaging was used to investigate the efficacy of microwave heating in GNP/PLA nanocomposites as a function of microwave power and filler weight fractions. The microwave heating process in GNP composites was studied using multi‐physics finite element software. The experimental results were compared to numerical model predictions for maximum temperature and microwave energy absorbed. The produced nanocomposites were discovered to have strong microwave absorption characteristics and hence rapid heating, making this type of composite a prospective choice for gasket materials that facilitate fusion bonding for thermoplastic‐based components via localized heating. [ABSTRACT FROM AUTHOR]

Nowadays, various machine learning (ML) approaches are widely used in different research areas. However, the need for a large training dataset has restricted the attractiveness of ML techniques for industrial applications, since the preparation of a large dataset is very costly and inefficient. To deal with this limitation, an efficient method is required to fill the gap between industry and research. For this purpose, in this study a transfer learning-based deep neural network (TL-DNN) model was developed to predict the mechanical properties of various graphene reinforced nanocomposites. In this respect, a hybrid multi-layer feedforward DNN was designed, containing one source network and one target network. The source DNN was trained to predict the mechanical properties of graphene/graphene oxide nanocomposites with various matrix types including Al, Cu, PMMA, Si3N4, Al2O3, etc. By transferring the acquired knowledge of the source DNN to the target DNN, the mechanical properties of another material (graphene/epoxy nanocomposite) were estimated with high accuracy level, even with limited number of data samples. It should be mentioned that the optimal values of the network hyperparameters were determined using genetic algorithm (GA), simulated annealing (SA) and particle swarm optimization (PSO) algorithms. [ABSTRACT FROM AUTHOR]

Composite failure due to in‐service low energy impact damage and moisture absorption is a major risk for these materials within aerospace, automotive and other engineering sectors. Deterioration in post‐impact flexural properties, and the tendency of thermosets to absorb moisture are some of the few drawbacks of carbon fiber reinforced polymers (CFRPs). Adding graphene into the matrix is theorized to improve mechanical properties and reduce moisture uptake. This study evaluates the diffusion characteristics and flexural properties of carbon fiber/epoxy composites modified with NH2 functionalized graphene (CFRP/graphene nanoparticle [GNPs]) before and after impact under various environmental conditions. Adding GNPs to CFRP decreased the flexural strength and modulus by 24% and 25% respectively before impact. After impact, the flexural strength and modulus decreased by 7.4%–23.6% and 37%–67%, respectively. For both composites after undergoing impact, the residual strength and stiffness were considerably reduced due to delamination and transverse cracking. Samples with graphene inclusion experienced a slower rate of ethanol and water diffusion, for both unimpacted and impacted samples, by 46.4% and 44.8%, respectively. Moisture uptake also reduced the flexural properties of both composites. Scanning electron microscopy revealed good dispersion but poor bonding of graphene to the matrix, which is believed to be the reason for property reduction. [ABSTRACT FROM AUTHOR]

In this work, simple, reliable, eco‐friendly, and quantitative electrochemical sensors were developed to detect chlorhexidine Digluconate (CHX) in a variety of dosage forms, including mouthwashes and intimate douches, as well as chlorhexidine in spiked human saliva. Without any sample pre‐treatment or extraction processes, CHX was measured in colored aqueous formulations. Based on carbon screen‐printed electrodes, two potentiometric sensors (sensors I and II), utilizing graphene nanocomposites (Gr‐NC), were designed (SPEs). An ionophore, 2‐hydroxypropyl‐β‐cyclodextrin, was doped into the Poly Vinyl Chloride (PVC) polymeric membrane to improve sensor selectivity. [ABSTRACT FROM AUTHOR]

Sensor arrays are currently attracting the interest of researchers due to their potential of overcoming the limitations of single sensors regarding selectivity, required by specific applications. Among the materials used to develop sensor arrays, graphene has not been so far extensively exploited, despite its remarkable sensing capability. Here we present the development of a graphene-based sensor array prepared by dropcasting nanostructure and nanocomposite graphene solution on interdigitated substrates, with the aim to investigate the capability of the array to discriminate several gases related to specific applications, including environmental monitoring, food quality tracking, and breathomics. This goal is achieved in two steps: at first the sensing properties of the array have been assessed through ammonia exposures, drawing the calibration curves, estimating the limit of detection, which has been found in the ppb range for all sensors, and investigating stability and sensitivity; then, after performing exposures to acetone, ethanol, 2-propanol, sodium hypochlorite, and water vapour, chemometric tools have been exploited to investigate the discrimination capability of the array, including principal component analysis (PCA), linear discriminant analysis (LDA), and Mahalanobis distance. PCA shows that the array was able to discriminate all the tested gases with an explained variance around 95%, while with an LDA approach the array can be trained to accurately recognize unknown gas contribution, with an accuracy higher than 94%. [ABSTRACT FROM AUTHOR]

We report the synthesis of reduced graphene oxide (rGO)-α-Fe2O3 nanocomposite and its application to remove and recover dissolved oil from a high-salinity oil–water emulsion in batch and column/breakthrough setups. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and nitrogen adsorption characterized the synthesized nanocomposite's structure, morphology, and surface properties. Both batch and continuous breakthrough adsorption studies were investigated. The effect of the adsorption parameters on the adsorption capacity and removal efficiency was analyzed. The rGO-Fe2O3 nanocomposite (rGO-Fe2O3-NC) demonstrated a superior adsorption capacity, both when measured experimentally (1213 mg/g) and predicted using the Freundlich isotherm (1301 mg/g). The adsorption process followed pseudo-second-order kinetic, and the rGO-Fe2O3-NC exhibited a very rapid removal, with more than 60% of oil being removed within 10 min. Breakthrough confirmed the exceptional removal capacities with good regeneration and cycling ability under a short contact time. Moreover, the adsorption capacity was enhanced with an emulsion salinity of up to 100,000 ppm, confirming the suitability for high-salinity wastewater. [ABSTRACT FROM AUTHOR]

Nanocomposites and nanomaterials have frequently useful advantages for drug delivery applications because of their excellent potential in cancer therapy. This study development of nanocomposites from graphene/N-phthaloylchitosan –graft- poly(methylmethacrylate-block-(poly ethylenglycol methacrylate -random-dimethylaminoethyl methacrylate), CS-g-P(MMA-b-(PEGMA-ran-DMAEMA), via reversible addition fragmentation chain transfer polymerization. The structure of the copolymer and nanocomposite were investigated by FT-IR and 1HNMR. The nanocomposites properties of GO/ CS-g-P(MMA-b-(PEGMA-ran-DMAEMA) were investigated by scanning electron microscopy (FE-SEM), dynamic light scattering, ultraviolet–visible (UV–Vis) spectroscopies, and thermogravimetry measurements. We developed a biodegradable GO nanocomposites to overcome limitations of doxorubicin (DOX)-loading. The drug loading efficiency of GO/nanocomposites for DOX was high, and 81% efficiency was obtained. Release behavior of DOX from the nanocomposites showed that the rate of DOX release is controlled by pH values. [ABSTRACT FROM AUTHOR]

Background: Increased intake of drugs worldwide and the subsequent advent of resistance to existing antibiotics have globally threatened health organizations. To combat the problem of these drug-resistant infections, as an alternative approach, graphene (GN)-related nanomaterials have attracted significant interest because of their effective anti-microbial potential. The present study shows the synthesis and characterization of nanocomposite of GN with carbon nitride viz. g- C3N4, g-C3N4-Cu, and GN@g-C3N4-Cu. Further, we investigated the anti-microbial potential of these nanocomposites against strains of Gram-negative and Gram-positive bacteria, viz., a multidrug- resistant strain of Pseudomonas aeruginosa (MDRPA), a methicillin-resistant strain of Staphylococcus aureus ATCC33593 (MRSA), and an azole-sensitive fungal strain (Candida albicans ATCC14053)., Methods: The morphological characterization of GN@g-C3N4-Cu nanocomposite was executed by scanning electron microscopy, whereas the elemental analysis and their distribution were studied by energy-dispersive X-ray spectroscopy and elemental mapping methods. Furthermore, the anti-microbial and antibiofilm efficacies of g-C3N4, g-C3N4-Cu, and GN@g-C3N4-Cu nanocomposites were evaluated by disc diffusion, two-fold serial micro broth dilution, and 96 well microtiter plate methods., Results: The ternary g-C3N4-Cu@GN, apart from the structures of g-C3N4-Cu, showed big sheets of GN. The observance of C, N, O, and Cu in the elemental analysis, as well as their uniform distribution in the mapping, indicated the successful fabrication of g-C3N4-Cu@GN. GN@g-C3N4-Cu followed by g-C3N4-Cu and (g-C3N4) exhibited significantly higher antimicrobial activity (zone of inhibition from 14.33 to 49.33 mm) against both the drug-resistant bacterial strains and azole-sensitive C. albicans. MICs of nanocomposites ranged from 32 -256 μg/ml against the tested strains. Whereas all three nanocomposites at sub-MICs (0.25 A- and 0.5 A- MICs) showed concentration- dependent inhibition of biofilm formation in MDRPA, MRSA, and C. albicans by allowing 11.35% to 32.59% biofilm formation., Conclusion: Our study highlights the enhanced efficiency of GN@g-C3N4-Cu nanocomposites as potential anti-microbial and antibiofilm agents to overcome the challenges of multi-drug-resistant bacteria and azole-sensitive fungi. Such kind of nanocomposites could be used to prevent nosocomial infections if coated on medical devices and food manufacturing instruments., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

In the present work, reduced graphene oxide (rGO)/poly(3,4-ethylene dioxythiophene) polystyrene sulphonate (PEDOT:PSS)/polyvinylpyrrolidone (PVP) composite films are synthesized with varying rGO content from 0 to 25wt.%. The estimated average particles' sizes evaluated from scanning electron microscope of rGO/PEDOT:PSS/PVP are found to be in the range between 2.43 µm and 4.11 µm. The broad XRD peak at 2θ ~ 21.4o to 23° corresponds to (002) plane of rGO in rGO/PEDOT:PSS/PVP. The FTIR results at 829, 1287, 1344, 1413, 1421, 1642, 2950 and 3393 cm−1 correspond to vibration bonding of (C–S), (C–C), (S–O), (C–O–H), (C–N), (C=O), (C–H) and (O–H) respectively. The Raman spectra, ID/IG ratio varies from 0.31 to 0.35 for 15–25 wt%, indicating that the nitrogen bonding with carbon atom decreased with increasing rGO content. The absorption spectra at ~ 243.9 nm and 281.2 nm correspond to (p–p*) and (n–p*) transitions respectively from 15 to 25 wt% of rGO. Form Tauc's plot optical bandgap was decreased from 5.2 to 4.79 eV with increasing of rGO contents. Thermal gravimetric analysis (TGA) spectrum indicates that thermal degradation of the rGO/PEDOT:PSS/PVP composite starts above ~ 350 °C. From CV analysis, the maximum specific capacitance was found to be 447.14 F/g and from the galvanic charge–discharge curve, the maximum specific capacitance was found to be 225.71 A/g for 25 wt% rGO content rGO/PEDOT:PSS/PVP. [ABSTRACT FROM AUTHOR]

Nitrogen-doped 2D graphene nanosheets were wrapped on the sphalerite structured pure and Cr substituted ZnS nanospheres synthesized by hydrothermal method successfully and examined as novel photocatalysts to the photodegradation of dye mixtures as realistic pollutants. 2D graphene nanosheets were successfully synthesized by Hummer's method using natural coal. XRD, Raman spectroscopy, and XPS were correlated to each other, and vacancy defects were found to increase in graphene/4% Cr:ZnS nanocomposites due to the existence of stacking faults, microstrain, dislocation density, grain boundaries, point defects, doping, and graphitic edges. The drastic change was noticed in C 1 s spectra of graphene and graphene/pure ZnS, graphene/4% Cr:ZnS nanocomposites owing to the stress, strain property of graphene, and development of vacancy defects. N-doped 2D graphene nanosheets were decorated on the surface of ZnS nanospheres which was confirmed by FESEM. The addition of 2D graphene nanosheets results in the enhancement of dislocation density, microstrain, and stacking faults in the samples. From XRD, the dislocation density, microstrain, and stacking faults were decreased due to the doping of Cr into the ZnS lattice. From XPS, it was verified that the highest vacancy defects were scrutinized in graphene/4% Cr:ZnS nanocomposite due to the ionic radius of Cr there were more vacancies were created into ZnS lattice. The dyes of methylene blue, para nitrophenol and, Congo red were mixed into 100 ml of water under solar light for degradation. The photocatalytic efficiencies were found to be 57.36, 62.79, 59.68, 84.49, and 51.16% for pure ZnS, 4% Cr:ZnS, graphene/pure ZnS, graphene/4% Cr:ZnS, and graphene, respectively. Morphological, chemical, and optical properties of graphene nanosheets based on Cr substituted ZnS nanocomposites were studied before and after the photocatalytic activity. [ABSTRACT FROM AUTHOR]

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We report the synthesis of reduced graphene oxide (rGO)-α-Fe2O3 nanocomposite and its application to remove and recover dissolved oil from a high-salinity oil–water emulsion in batch and column/breakthrough setups. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and nitrogen adsorption characterized the synthesized nanocomposite’s structure, morphology, and surface properties. Both batch and continuous breakthrough adsorption studies were investigated. The effect of the adsorption parameters on the adsorption capacity and removal efficiency was analyzed. The rGO-Fe2O3 nanocomposite (rGO-Fe2O3-NC) demonstrated a superior adsorption capacity, both when measured experimentally (1213 mg/g) and predicted using the Freundlich isotherm (1301 mg/g). The adsorption process followed pseudo-second-order kinetic, and the rGO-Fe2O3-NC exhibited a very rapid removal, with more than 60% of oil being removed within 10 min. Breakthrough confirmed the exceptional removal capacities with good regeneration and cycling ability under a short contact time. Moreover, the adsorption capacity was enhanced with an emulsion salinity of up to 100,000 ppm, confirming the suitability for high-salinity wastewater.

The mitigation of electromagnetic pollution is becoming an increasing issue due to the proliferation and miniaturization of electronic components. Electromagnetic interference (EMI) shields must be considered to bring about electromagnetic compatibility (EMC), where analyzing the shielding effectiveness (SE) is of great importance. Graphene-enhanced polymer composite materials are recently introduced as a replacement for metal-based EMI shielding materials due to their low cost, resistance to corrosion, lightweight, versatile, and straightforward processability, as well as broad bandwidth properties compared to conventional metal-based materials. The SE can be determined from the bulk material properties, including permittivity, permeability, and conductivity, using analytical or numerical solutions to Maxwell's equations. Though, Due to the heterogeneity of graphene-based polymer composites, characterization of these values remains difficult. This article attempts to summarise and critically review the state-of-the-art progress in the fabrication and characterization of these materials. Also, this review elaborates on accurate modelling techniques based on the underlying micromechanics, e.g., percolation, electron tunnelling, agglomeration, imperfect interface, frequency-dependent nanocapacitance and electron hopping. The model is designed to predict the electromagnetic properties of the nanocomposite from the pre-determined properties of the polymer matrix and carbon-based filler. This understanding may ultimately lead to the development of graphene/polymer composites with optimized EMI shielding properties to develop emerging EMI shielding materials. This paper focuses heavily on Graphite Nanoplatelet (GnP)/Epoxy as the choice of graphene/polymer.

Nanomaterials are frequently demonstrating advantages for drug delivery applications due to their high potential in treatment of variety of cancers. This paper reports the development of termoresponsive nanocomposites from graphene/(β-Cyclodextrin)-star poly(methyl methacrylate)-block-poly(N-Isopropylacrylamide) GO/β-Cyclodextrin-star-PMMA-b-PNiPAM via reversible addition fragmention chain transfer (RAFT) polymerization. The drug loading efficiency of GO/nanocomposites for DTX was high and 85% efficiency was obtained. The cytotoxicity of the DTX against breast cancer cell line (MCF7) was exhibited by using the cytotoxicity assays (MTT), DAPI staining, and cellular uptake. These intelligent GO/nanocomposites with increased anticancer activity could be chosen as an ideal nanocarrier for anticancer therapy. [ABSTRACT FROM AUTHOR]

• A modified Halpin-Tsai model to take into account the effects of the agglomeration threshold, the filler-matrix interfacial moduli, and the surfactant treatment is proposed. • Cauchy's cumulative probability function is first introduced to describe the progressive deterioration of the filler-matrix interface as the graphene's volume concentration increases. • The synergistic effect of filler-matrix interface and filler agglomeration in the overall Young's modulus of composites was confirmed, and the latter becomes increasingly dominant as the graphene volume concentration increases. Filler agglomeration can severely hinder the stress transfer at the graphene-polymer interface, leading to deterioration of the interfacial properties and the overall mechanical performance of graphene nanocomposites. However, the correlation between the agglomeration and the interface effect was rarely investigated in the past. We hereby propose a novel and efficient approach to accurately obtain the effective Young's modulus of graphene nanocomposites. We first introduced Cauchy's cumulative probability function to describe the progressive deterioration of the filler-matrix interface as the graphene's volume concentration increases. Then, via the shear-lag approach, we developed a modified Halpin-Tsai model to take into account the effects of the agglomeration threshold, the filler-matrix interfacial moduli, and the surfactant treatment. The entire approach was validated by comparing the predicted results with five groups of experimental data. It was found that the interfacial properties are roughly linearly related to the matrix-to-nanofiller modulus ratio, which illustrates that a severer interfacial modulus mismatch leads to poorer interfacial bonding quality, and thus to a lower overall elastic modulus. The interfacial coefficient can also quantitatively characterize the enhancement effect of surfactant treatment. Besides, the synergistic effect of filler-matrix interface and filler agglomeration in the overall Young's modulus of composites was confirmed by comparison between theoretical and experimental results, and the latter becomes increasingly dominant as the graphene volume concentration increases. [ABSTRACT FROM AUTHOR]

Copper was formerly used for the antenna conductive patch, which was expensive, subject to multipath fading, bulky, ecologically sensitive, and difficult to manufacture. The miraculous nanotechnology of graphene has made it a feasible contender to replace copper due to its extraordinary electrical conductivity and greater strength compared to metal, all while being adaptable and flexible. As a consequence, graphene is utilized in this study to create conductive silver nanocomposites. The electrical conductivity of pressed pellets of the silver-graphene (Ag/GO) sample is measured using the four-point probe method, resulting in an electrical conductivity value of approximately 21.386 S/cm. The proposed wearable antenna is designed, measured, and fabricated, consisting of a circular patch embedded with four slots to enhance the impedance bandwidth, resonating at 2.45 GHz. Besides, the wearable antenna has achieved a high gain of 11.78 dBi and a return loss of more than −20 dB. In consideration of health and safety concerns in wearable devices, the specific absorption rate (SAR) is evaluated. The SAR is determined to be 0.9 W/kg per 10 g of tissue for an input power of 0.5 W, confirming the safety of the proposed graphene wearable antenna for use in wearable devices. These findings suggest promising prospects for the utilization of Ag/GO nanocomposites as a conductive patch for wearable antennas in wireless communication. [ABSTRACT FROM AUTHOR]

Recently, stretchable conductors and electrodes with hierarchically 3D foams have been highlighted for the development of simple and cost‐effective systems with enhanced performance in sensors, absorbents, energy storage devices, medical devices, and catalysts. For better versatility, additional properties such as mechanical robustness, water repellency, and thermal resistance are required for stable operation in tough, dry/wet conditions. Herein, a novel strategy is reported to fabricate highly robust and large‐area foam‐type conductor with a multiscale 3D matrix of a graphene/polymer nanocomposite (GNC) using a nickel‐based template. The 3D foam conductor with hierarchically porous GNC structures presents excellent stretchability (<160%), water repellency (contact angle > 126°), fire retardancy (>400 °C), and shock‐absorbing ability (>300 kPa), enabling potential application as versatile conductors working under extreme environments. In addition, it is demonstrated that the 3D GNC foam conductor can be used for healthcare electrode operating in wet environments under mechanical bending strain. It is believed that this work overcomes the lack of versatility of conventional bulk or 3D conductive polymer composites and can pave the way for the development of high‐performance, tough, and non‐wettable conductor that can operate under extreme environments. [ABSTRACT FROM AUTHOR]

Nanomaterials with their extremely high free surfaces can effectively augment damping in nanocomposites via frictional sliding along the interface of nanomaterials and a matrix. Despite this potential, existing state of knowledge about the damping behavior of graphene reinforced nanocomposites is at an embryonic stage. In particular, it is not clear how various morphological parameters of graphene contribute to damping. We aim to reveal the mechanical damping behavior of graphene-reinforced polymer nanocomposites as a function of the surface morphology of graphene nanoplatelets through combined experiments and continuum modeling. The vibrational damping behavior of graphene nanocomposites was studied via dynamic mechanical analysis via cycling tension-compression tests. Two graphene types, "single-layer graphene" (SLG) and "graphene nanoplatelets" (GNP), with different aspect ratios in polystyrene (PS) matrix were used. We developed a micromechanical model which relates damping in nanocomposites to filler-matrix frictional sliding. The experimental work demonstrated that the addition of GNP will increase the damping properties of the nanocomposites by up to ~70%. The model predictions for PS-GNP were in good agreement with experimental data. However, contrary to the model predictions, the damping coefficient of nanocomposites with lower aspect ratio particles (PS-SLG) was lower than PS-GNP. Further experimental studies showed that the surface roughness of the SLG (owed to their small thickness) has a negative effect on damping properties as they delay interfacial debonding and frictional sliding. Flat (less rough) graphene triggers intrinsic friction mechanism earlier and may be more beneficial to enhance damping. Surface undulation of the nanoparticles, which can happen for atomically thin particles, will delay damping. [ABSTRACT FROM AUTHOR]

High-efficiency microwave absorption epoxy nanocomposites filled with ultralow content of non-covalently modified reduced graphene oxides (rGO) are prepared via an in-situ polymerization method. Here, the porous and folded rGO nanosheets are successfully functionalized by strong π-π interaction between conjugated imidazole and graphene sheets. The combination of electron microscope and synchronous radiation X-ray small angle scattering (SAXS) techniques unambiguously illustrates that the non-covalently modified graphene nanosheets in the epoxy composites are well-dispersed and extensively winkle. Hence, compared with pristine rGO/epoxy composites, the composites containing the highly dispersed rGO demonstrate more ideal impedance matching and stronger microwave dissipation based on the experimental and simulated results. The composites remarkably achieve excellent microwave absorptions (minimum reflection loss of −65 dB, with a matching thickness of 1.8 mm), an extremely broad absorbing bandwidth of 7.48 GHz (RL < −10 dB) and ultralow filler loading (1–2 wt%). Moreover, the composites possess high hydrophobicity, endowing them attractive functions of self-cleaning. This work provides a promising, facile and scalable approach for designing and fabricating graphene-based nanocomposites with hydrophobicity and excellent microwave absorption capacities. Image 1 [ABSTRACT FROM AUTHOR]

Graphene-based nanocomposites possess excellent mechanical, electrical, thermal, optical, and chemical properties. These materials have potential applications in high-performance transistors, biomedical systems, sensors, and solar cells. This paper presents a critical review of the recent developments in graphene-based nanocomposite research, exploring synthesis methods, characterizations, mechanical properties, and thermal properties. Emphasis is placed on characterization techniques and mechanical properties with detailed examples from recent literature. The importance of characterization techniques including Raman spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) for the characterization of graphene flakes and their composites were thoroughly discussed. Finally, the effect of graphene even at very low loadings on the mechanical properties of the composite matrix was extensively reviewed.

In situ intercalative polymerization has been investigated as a strategic way to obtain poly(propylene 2,5-furandicarboxylate) (PPF) and poly(hexamethylene 2,5-furandicarboxylate) (PHF) nanocomposites with different graphene types and amounts. Graphene (G) has been dispersed in surfactant stabilized water suspensions. The loading range in composites was 0.25–0.75 wt %. For the highest composition, a different type of graphene (XT500) dispersed in 1,3 propanediol, containing a 6% of oxidized graphene and without surfactant has been also tested. The results showed that the amorphous PPF is able to crystallize during heating scan in DSC and graphene seems to affect such capability: G hinders the polymer chains in reaching an ordered state, showing even more depressed cold crystallization and melting. On the contrary, such hindering effect is absent with XT500, which rather induces the opposite. Concerning the thermal stability, no improvement has been induced by graphene, even if the onset degradation temperatures remain high for all the materials. A moderate enhancement in mechanical properties is observed in PPF composite with XT500, and especially in PHF composite, where a significative increase of 10–20% in storage modulus E’ is maintained in almost all the temperature range. Such an increase is also reflected in a slightly higher heat distortion temperature. These preliminary results can be useful in order to further address the field of application of furan-based polyesters; in particular, they could be promising as packaging materials.

Polybutylene Succinate (PBS)/Graphene nanoplatelets (GnP) nanocomposites over a range of GnP from 0 to 1.35 wt.%. were prepared by a melt process. A mixture of individual graphene nanosheets and aggregates was obtained by the addition of GnP in the PBS matrix. The presence of these fillers did not significantly modify the morphology, crystalline microstructure of the matrix or its thermal stability. However, a slight reinforcement effect of PBS was reported in the presence of GnP. The water sorption isotherm modelling with Guggenheim, Andersen and De Boer (GAB) equation and Zimm-Lundberg theory allowed a phenomenological analysis at the molecular scale. The presence of GnP did not modify the water sorption capacity of the PBS matrix. From a kinetic point of view, a decrease of the diffusion coefficient with the increasing GnP content was obtained and was attributed to a tortuosity effect. The influence of water activity was discussed over a range of 0.5 to 1 and 0 to 0.9 for water and dioxygen permeability. Improvement of the barrier properties by 38% and 35% for water and dioxygen permeability respectively were obtained.

In this paper, gold nanoparticles (AuNPs) modified by thiolated calix[n]arene (TCnA, n = 4, 6, 8) were anchored on graphene nanosheets (GN) by π-π stacking interaction between TCnA molecules and GN. Testing of various electrochemical techniques display that the AuNPs@TCnA/GN modified glass carbon electrodes (GCE) show good electrocatalytic property, molecular recognition and enrichment performance toward dopamine (DA) and acetaminophen (AC), and exhibit high current response. In all of modified electrodes, AuNPs@TC8A/GN/GCE shows an outstanding electrochemical response for DA and AC with high sensitivity of 5.08 and 9.76 mA mmol−1 L cm−2, respectively. The analytical curves for DA obtained by differential pulse voltammetry (DPV) are linear in the range from 0.5 to 150 μM and from 0.3 to 1.0 mM. The linear range for AC obtained by DPV is from 0.5 to 120 μM. Besides, AuNPs@TC8A/GN/GCE can be applied to determinate of DA and AC simultaneously, implying the prospect to develop a dual sensor under the same construction platform. Image 1 • AuNPs@TCnA/GN is fabricated by π-π stacking interaction between TCnA molecules and GN. • AuNPs@TCnA/GN/GCE showed outstanding electrochemical response for DA and AC. • AuNPs@TC8A/GN/GCE can be applied to the simultaneous determination of DA and AC. • Excellent property is attributed to the synergistic effect of GN, AuNPs, and TC8A. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) based composites were synthesized using a hydrothermal process, by these means, it was possible to tailor the loading of titanate nanotubes (TNTs) and TiO 2 anatase particles in order to get insights into the photoactivity of the as-prepared photocatalyst. GO was prepared by the modified Hummers' method. The interactions stuck between titanium nanostructures and GO were studied by XRD, FESEM, FTIR, UV–vis and N 2 physisorption along with computational studies using the DFT formalism on a graphene-TiO 2 model. The photocatalytic performance was evaluated in the degradation of 4-clorophenol (4-CP) under UV light. The coexistence of anatase and titanate crystalline phases grown on the GO defects gave adsorptive and photocatalytic properties to the GO-based nanocomposites (TGO) and the favorable adsorption energy calculated by the DFT computational method showed that formyl acid surface groups on the tip area featured the main interaction of the TiO 2 -based photocatalyst. As a result, a photocatalyst with high surface area and functional sites was obtained, thus boosting the photoactivity and mass transfer properties to remove 4-CP from wastewater. Cycle voltammetry and electrochemical impedance measurements of the optimal TGO opened the possibility for using this material as a capacitor. [ABSTRACT FROM AUTHOR]

In this paper, a data-driven-based computational homogenization method based on neural networks is proposed to describe the nonlinear electric conduction in random graphene-polymer nanocomposites. In the proposed technique, the nonlinear effective electric constitutive law is provided by a neural network surrogate model constructed through a learning phase on a set of RVE nonlinear computations. In contrast to multilevel (FE 2 ) methods where each integration point is associated with a full nonlinear RVE calculation, the nonlinear macroscopic electric field-electric flux relationship is efficiently evaluated by the surrogate neural network model, reducing drastically (by several order of magnitudes) the computational times in multilevel calculations. Several examples are presented, where the RVE contains aligned graphene sheets embedded in a polymer matrix. The nonlinear behavior is due to the modeling of the tunelling effect at the scale of graphene sheets. [ABSTRACT FROM AUTHOR]

Graphene-polymer nanocomposites are innovative materials that have attracted much attention due to their novel features. Herein, we report photocatalytic and antibacterial properties of GNP-PPy nanocomposites. The formation of nanocomposites was confirmed by various characterization techniques. The assembly of GNPs and PPy NPs with optimized GNP content amazingly increased the photocatalytic degradation of bromophenol blue (BPB) up to 93% under solar light irradiation in 120 min. The antibacterial assay revealed that 50% GNPs-PPy nanocomposite showed a best (32.43%) inhibition of growth against a Gram negative bacteria E. coli. The GNP-PPy nanocomposites can possibly be utilized as multifunctional material for wastewater treatment and as antimicrobial agent. Image 1 • Graphene/PPy nanocomposites show good photocatalytic activity under sunlight. • The materials also show moderate antibacterial activity. [ABSTRACT FROM AUTHOR]

We present a high-scale method to produce few-layer graphene (FLG) based on the mechanical exfoliation of graphite and compare the obtained FLG with the one reported earlier arising from pencil lead ablation. Several elements were modified and improved in the new approach. The purification and the ablation set-up were simplified, and the morphology of the FLG was modified and improved in view of some applications. The morphology-dependent properties of FLGs, lead-FLG, and graphite-FLG as conductive layers and in nanocomposites were investigated. The newly obtained FLG had a higher aspect ratio (high lateral size vs thickness/higher 2D aspect), which is reflected by enhanced transparency-conductivity features of the layer (film) and elongation-at-break behavior of the polymer composites. On the contrary, the nanocomposite containing lead-FLG showed, for instance, excellent gas barrier properties due to the multi-step structure of the lead-FLG flakes. Such structure exhibited less 2D and more 3D character, which can be highly suitable for applications where the presence of active/reactive edges is beneficial, e.g., in catalysis or supercapacitors' electrodes. Nuclear reaction analysis was employed to investigate the morphology of graphite-FLG film. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A solar light activated graphene/Fe 3 O 4 nanocomposite is prepared and characterized. • Graphene content effects dye degradation and eradication of bacteria. • A 99.42% removal of dye with TON = 47.22 x 102 and TOF = 8.1. • 89.02% and 95.33% eradication of P. aeruginosa and S. aureus respectively. Abstract Graphene nanoplatelets provide unique nanoplatform for photocatalysis and pathogen control due to their purity and high electrical conductivity. Graphene/Fe 3 O 4 nanocomposite is investigated for its performance against removal of methyl orange. A fast and complete removal of dye (99.42%) is achieved using magnetic graphene/Fe 3 O 4 nanocomposite under solar light irradiation, which otherwise can be removed only 72% using Fe 3 O 4 alone. A high photodegradation (99.42%) is associated with a high ToN (47.22 × 102) and ToF (8.1) of the photocatalyst at halfway of reaction. In addition, the growth inhibition of both Gram positive and Gram negative bacteria is studied. Interestingly, it is observed that 89.02% and 95.33% growth of Pseudomonas aeruginosa and Staphylococcus aureus is inhibited by graphene/Fe 3 O 4 nanocomposite. We anticipate that economical method based on solar-Fenton like reaction will pave the way for employment of graphene/Fe 3 O 4 nanocomposite in practical applications as a multifunctional material that possesses potential to remove organic dye, along with bacterial disinfection features. [ABSTRACT FROM AUTHOR]

Highlights • Synthesis, characterizations of Bi nanoparticles@graphenated carbon nanotubes. • Excellent mercury sensing ability via differential pulse voltammetry. • Linear range 1.0 nM–217.4 µM and detection limit 0.2 nM. • Highly selective, durable, reproducible. • Practicality in tap water, fish oil tablet, human serum, and urine samples. Abstract A three-dimensional hierarchical network of bismuth nanoparticles decorated graphene-carbon nanotubes nanocomposite (Bi NPs@Gr-CNTs) was synthesized and employed for electrocatalytic detection of mercury (Hg (II)). The electrocatalyst was characterized via scanning electron microscopy, transmission electron microscopy, Energy-dispersive X-ray spectroscopy, X-ray diffraction, FT-IR, electrochemical impedance spectroscopy, and cyclic voltammetry. The electrocatalytic activity of Bi NPs@Gr-CNTs modified screen-printed carbon electrode (SPCE) toward Hg (II) was studied using cyclic voltammetry, and differential pulse voltammetry. The Bi NPs@Gr-CNTs/SPCE exhibited excellent electrocatalytic ability to Hg (II) in comparison to control electrodes. Under optimized conditions, Bi NPs@Gr-CNTs/SPCE exhibits excellent Hg (II) sensing attributes in the range of 1.0 nM–217.4 µM with 0.2 nM of detection limit. The electrode was specific for Hg (II) in presence of other metal ions ascribe excellent selectivity. Practicality of the method was demonstrated in tap water, fish oil tablet, human serum, and urine samples (spiked method), which presented acceptable recoveries. Graphical abstract Image, graphical abstract Bi NPs@Gr-CNTs nanocomposite for electrocatalytic mercury sensor. [ABSTRACT FROM AUTHOR]

The accurate determination of oxidative stress biomarker 3-nitro- l -tyrosine (3-NT) in biological medium is of high medical significance. Here, we report an electrochemical sensor for 3-NT using CdWO 4 nanodots decorated reduced graphene oxide nanocomposite (CdWO 4 ND@RGO) modified screen-printed electrode. The morphological and structural aspects of the composite were analyzed using transmission electron microscopy, Energy-dispersive X-ray spectroscopy, Raman, and X-ray diffraction techniques. The electrochemical and interfacial properties were tested via voltammetry and impedance measurements, respectively. The CdWO 4 ND@RGO was coated on a screen-printed electrode, and the resulting modified electrode displays excellent electrocatalytic ability to 3-NT. An amperometric sensor was fabricated which displayed good sensitivity in the linear range of 18.5 nM–1.84 mM. The detection limit was 3.24 nM (S/N = 3) which surpassed the limits of many existing methods Most of the previously reported 3-NT sensors depends on expensive analytical methods, whereas, the described method is a simple, low-cost, easy-to-make modified electrode that works well even in real samples such as human serum and urine. [ABSTRACT FROM AUTHOR]

Because of its unique two-dimensional structure, huge specific surface area, high electrical conductivity, and other excellent performances, graphene has shown great potential for application in catalysis, electronics, sensors, energy storage, and other areas. Especially, graphene nanocomposites have been found to be promising catalyst support for low-temperature fuel cells, and as anode nanomaterials for high reversible capacity and excellent rate capability for lithium-ion batteries, which has triggered a new round of research hotspot. Preparation methods of graphene nanocomposites mainly for low-temperature fuel cells are reviewed. Particularly, the research progress and principles of physical preparation methods (molecular beam epitaxy), chemical preparation methods (chemical reduction, electrochemical deposition and hydrothermal/solvothermal methods, etc.) and high-energy ball milling are summarized. Research outlook of graphene nanocomposites for low-temperature fuel cells are prospected.

Urethane-acrylate thermoset resins (UATR) are a new type of polymeric matrix that have recently made a strong breakthrough in the composites sector. This is because of their properties, which make them an advantageous alternative to epoxy resins, especially if they are reinforced with high-performance fibers such as aramids. Graphene-based nanocomposites are one of the most dynamic research fields in nanotechnology, because graphenic materials greatly improve the properties of traditional composites. This work represents a comparative study of the effect of adding three types of graphenic materials on the mechanical properties of UATR/aramid composites. Several UATR polymeric matrices were doped at 2% w/w with graphene nanoplatelets (GNPs), reduced graphene oxide (rGO) and pristine few-layer graphene (FLG), and reinforced with Twaron CT709 para-aramid fibers. The obtained laminates showed low density (1.38 g·cm−3), a high volumetric fiber–resin ratio (80:20), homogeneous dispersion of the nanoreinforcement, high reproducibility, and easy scalability. The tensile, flexural and impact strength properties of the undoped composite and the graphene-doped nanocomposites were determined. FLG-doped nanocomposites showed the highest increase in all the mentioned mechanical properties and attained a very significant relative improvement over the undoped laminate (up to 134.4% in aCU).

The presence of traces of heavy metals in wastewater causes adverse health effects on humans and the ecosystem. Adsorption is a low cost and eco-friendly method for the removal of low concentrations of heavy metals from wastewater streams. Over the past several years, graphene-based materials have been researched as exceptional adsorbents. In this review, the applications of graphene oxide (GO), reduce graphene oxide (rGO), and graphene-based nanocomposites (GNCs) for the removal of various metals are analyzed. Firstly, the common synthesis routes for GO, rGO, and GNCs are discussed. Secondly, the available literature on the adsorption of heavy metals including arsenic, lead, cadmium, nickel, mercury, chromium and copper using graphene-based materials are reviewed and analyzed. The adsorption isotherms, kinetics, capacity, and removal efficiency for each metal on different graphene materials, as well as the effects of the synthesis method and the adsorption process conditions on the recyclability of the graphene materials, are discussed. Finally, future perspectives and trends in the field are also highlighted.