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Present work demonstrates the synthesis, characterisation and application of a novel hybrid nanocomposite GO@Fe3O4-MnO2 for adsorption and catalytic degradation of dyestuff malachite green and tartrazine from wastewater. The nanocomposite GO@Fe3O4-MnO2 was characterised by FT-IR, XRD, SEM-EDS and pHzpc. Effects of various optimising parameters such as contact time, solution pH, surfactants, light, adsorbent dose, ultrasonication and coexisting ions were investigated. The removal efficiencies of malachite green and tartrazine were observed as high as 99.9% and 98% under direct sunlight, respectively. The adsorption kinetics follows the pseudo-second order model (R2 = 0.99) where k2 for malachite green and tartrazine were 0.0097 and 0.0011 g mg−1 min−1, respectively, that means adsorption was controlled by chemisorption. Equilibrium adsorption isotherm of these dyes was analysed in the context of Langmuir and Freundlich models, and the maximum adsorption capacity for Langmuir isotherm was found to be 8.0 and 5.1 mg g−1 for malachite green and tartrazine, respectively. The percentage removal was initially low, but when the ultrasound was irradiated, the removal percentage (96% for malachite green and 98% for tartrazine) was drastically increased because of the formation of highly active •H and •OH radicals in the water through the decomposition of water molecules by the formation of hot spots. On treatment with H2O2, advance oxidation processes were observed with high remediation percentage (99.5% for malachite green and 98% for tartrazine) of dye. The synthesised GO@Fe3O4-MnO2 was finally used for the treatment of dyes from real water samples. The used nanocomposite was separated using an external magnet and recycled with 0.1 N HCl or 0.1 N NaOH as desired. [ABSTRACT FROM AUTHOR]

Abstract A disposable screen-printed sensor has been crafted specifically for therapeutic drug monitoring purposes, particularly for detecting ofloxacin in biological fluids. To enhance selectivity toward ofloxacin, a supramolecular calix [6] arene serves as the ionophore of choice. The sensor incorporates a graphene nanocomposite as an ion-to-electron transducer layer, which not only boosts potential stability but also mitigates potential drift. The developed ofloxacin sensor underwent rigorous characterization following IUPAC guidelines. The linearity range spans from 1 × 10–6 to 1 × 10–2 M, with a measured slope of 59.0 mV/decade. Impressively, it boasts a percentage recovery of 100.18 ± 1.60 and a low detection limit (LOD) of 6 × 10–7 M. Stability assessments indicate reliable performance over an extended period of 8 weeks. The versatility of this sensor extends to various applications, including the determination of ofloxacin in pharmaceutical formulations, bulk powder, and biological fluids. Notably, it has demonstrated efficacy post-bioanalysis validation, adhering to Food and Drug Administration regulations. This advancement holds promise for personalized therapeutic drug monitoring in clinical pharmacy studies and quality control laboratories, thereby optimizing patient care at the point-of-care. Graphical abstract

A disposable screen-printed sensor has been crafted specifically for therapeutic drug monitoring purposes, particularly for detecting ofloxacin in biological fluids. To enhance selectivity toward ofloxacin, a supramolecular calix [6] arene serves as the ionophore of choice. The sensor incorporates a graphene nanocomposite as an ion-to-electron transducer layer, which not only boosts potential stability but also mitigates potential drift. The developed ofloxacin sensor underwent rigorous characterization following IUPAC guidelines. The linearity range spans from 1 × 10–6 to 1 × 10–2 M, with a measured slope of 59.0 mV/decade. Impressively, it boasts a percentage recovery of 100.18 ± 1.60 and a low detection limit (LOD) of 6 × 10–7 M. Stability assessments indicate reliable performance over an extended period of 8 weeks. The versatility of this sensor extends to various applications, including the determination of ofloxacin in pharmaceutical formulations, bulk powder, and biological fluids. Notably, it has demonstrated efficacy post-bioanalysis validation, adhering to Food and Drug Administration regulations. This advancement holds promise for personalized therapeutic drug monitoring in clinical pharmacy studies and quality control laboratories, thereby optimizing patient care at the point-of-care. [ABSTRACT FROM AUTHOR]

Numerous scientific and technological developments in wastewater treatment procedures are brought on by the shortage of clean water supplies. Heavy metals' recalcitrance in wastewater has been shown to be a difficult issue. Further, drinking water quality must be at its highest for human health to be at its best; nevertheless, a number of human activities are continuously degrading it, which has an effect on human health either directly or indirectly. Because heavy metals are the primary causes of many chronic illnesses and have a tendency to bio accumulate, they are giving rise to a lot of worries. Technologies from all over the world are being developed to address the demand for clean drinking water. The objective of the current study is to raise awareness of the need to remove dangerous dense metals from various types of wastewater and the application of modified graphene nanocomposite for their adsorption-based removal. Graphene-based nanocomposite materials have been picked for this application due to their large surface area, superior mechanical strength, and reactivity towards polar and nonpolar contaminants for the electrostatic emission of the heavy metal ions arsenic (As), chromium (Cr), copper (Cu), and lead (Pb). [ABSTRACT FROM AUTHOR]

Advanced nanoelectromechanical systems made from polymer dielectrics deposited onto 2D-nanomaterials such as graphene are increasingly popular as pressure and touch sensors, resonant sensors, and capacitive micromachined ultrasound transducers (CMUTs). However, durability and accuracy of layered nanocomposites depend on the mechanical stability of the interface between polymer and graphene layers. Here we used molecular dynamics computer simulations to investigate the interface between a sheet of graphene and a layer of parylene-C thermoplastic polymer during large numbers of high-frequency (MHz) cycles of bending relevant to the operating regime. We find that important interfacial sliding occurs almost immediately in usage conditions, resulting in more than 2% expansion of the membrane, a detrimental mechanism which requires repeated calibration to maintain CMUTs accuracy. This irreversible mechanism is caused by relaxation of residual internal stresses in the nanocomposite bilayer, leading to the emergence of self-equilibrated tension in the polymer and compression in the graphene. It arises as a result of deposition–polymerization processing conditions. Our findings demonstrate the need for particular care to be exercised in overcoming initial expansion. The selection of appropriate materials chemistry including low electrostatic interactions will also be key to their successful application as durable and reliable devices. [ABSTRACT FROM AUTHOR]

Under thermal environment and axial forces, the dynamic instability of functionally graded graphene platelet (GPLs)-reinforced porous beams on an elastic foundation is investigated. Three modes of porosity distributions and GPL patterns are considered. The governing equations are given by the Hamilton principle. On the basis of the differential quadrature method (DQM), the governing equations are changed into Mathieu–Hill equations, and the main unstable regions of the porous composite beams are studied by the Bolotin method. Thermal buckling and thermo-mechanical vibration problems are also studied. The effects of porosity coefficients and GPL weight fraction, dispersion pattern, initial thermal loading, slenderness ratio, geometry and size, boundary conditions, and foundation stiffness are discussed. The conclusions show that an elastic foundation has an obvious enhancement effect on thermal buckling, free vibration, and dynamic instability, which improves the stiffness of the beam. [ABSTRACT FROM AUTHOR]

Two different types of graphene materials were used as functional nanofillers for the mechanical and tribological improvement of silicon carbide/graphene nanocomposites. On the one hand is thermally reduced graphite oxide (TRGO) reduced at three different temperatures, and on the other hand is graphene made of three different organic precursors, which were directly coated on silicon carbide (SiC) platelets (GSiC). Additionally, benchmark materials were also used as carbon fillers. The SiC/graphene nanocomposites with 2 wt% filler content were manufactured by pressureless sintering (PLS). Some composites were produced with higher graphene contents of 4% and 8% and sintered by spark plasma sintering (SPS). Microstructural analyses were conducted using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Underwater lubrication, the SP sintered TRGO and GSiC materials with high graphene content have shown the most promising tribological performance. Furthermore, the reduced size of the homogeneously distributed nanoparticles promotes the formation of surface states, which improve the friction and wear properties. [ABSTRACT FROM AUTHOR]

We fabricated a novel nanocomposite composed of graphene-La2CrFeW6 perovskite compounds with an organic-inorganic counter electrode based on CdSe, gallic acid, urea and sulfate in dye-sensitized solar cells (DSSCs) by a simple hydrothermal technique. The nanocomposite shows an excellent electro–catalytic activity with low charge-transfer resistance, due to the synergetic catalytic effects of the graphene sheets and La2CrFeW6 perovskite with organic-inorganic materials. The special structure of this nanocomposite also improves the active sites for reduction of triiodide ions on the counter electrodes. The photo-conversion efficiency of the DSSC fabricated using a gallic-based counter electrode reached a higher value of 10.40% under standard illumination (1 sun, 100 mW cm−2, AM 1.5), as compared to the traditional Pt electrode (7.49%). The graphene-La2CrFeW6 fabricated with an organic-inorganic based CE was also found to be more efficient than those reported in previous works, in which graphene, produced by various methods, was used as a CE material. Therefore, the present nanocomposite is considered an environmentally friendly, low-cost, and highly efficient CE material for DSSCs.

The fast industrialization and mounting pollution have necessitated the need for advanced materials in order to degrade pollutants efficiently. Metal oxide-based and graphene-derivative photocatalytic nanocomposites are excellent for harnessing light energy in environmental remediation. Among them, ZnO-based nanocomposites have drawn considerable attention because of their high photocatalytic activity and stability. However, improving the performance of these nanocomposites is still necessary for their wide applications. This study explores the green synthesis, detailed characterization, and enhanced photocatalytic efficiency of reduced graphene oxide rGO/ZnO/Fe3O4 nanocomposites. The nanocomposites were synthesized via a hydrothermal method, utilizing milk thistle extract as a natural reducing agent, representing a novel and sustainable approach to fabricating magnetic rGO/Fe3O4 nanocomposites. These composites were further integrated with zinc oxide to produce a multifunctional material, exhibiting high surface area, superior electrical and thermal conductivity, and robust mechanical strength. The photocatalytic performance was significantly enhanced due to the synergistic interaction between graphene and metal oxide nanoparticles, leading to efficient degradation of environmental pollutants. Electrochemical analysis via cyclic voltammetry revealed distinctive redox peaks, demonstrating efficient electron transfer processes essential for applications in energy conversion and storage. This green synthesis not only provides a sustainable pathway for the development of advanced nanocomposites but also underscores their potential in a wide range of applications, including environmental remediation, sensing, energy storage, and optoelectronics.Graphical Abstract: The fast industrialization and mounting pollution have necessitated the need for advanced materials in order to degrade pollutants efficiently. Metal oxide-based and graphene-derivative photocatalytic nanocomposites are excellent for harnessing light energy in environmental remediation. Among them, ZnO-based nanocomposites have drawn considerable attention because of their high photocatalytic activity and stability. However, improving the performance of these nanocomposites is still necessary for their wide applications. This study explores the green synthesis, detailed characterization, and enhanced photocatalytic efficiency of reduced graphene oxide rGO/ZnO/Fe3O4 nanocomposites. The nanocomposites were synthesized via a hydrothermal method, utilizing milk thistle extract as a natural reducing agent, representing a novel and sustainable approach to fabricating magnetic rGO/Fe3O4 nanocomposites. These composites were further integrated with zinc oxide to produce a multifunctional material, exhibiting high surface area, superior electrical and thermal conductivity, and robust mechanical strength. The photocatalytic performance was significantly enhanced due to the synergistic interaction between graphene and metal oxide nanoparticles, leading to efficient degradation of environmental pollutants. Electrochemical analysis via cyclic voltammetry revealed distinctive redox peaks, demonstrating efficient electron transfer processes essential for applications in energy conversion and storage. This green synthesis not only provides a sustainable pathway for the development of advanced nanocomposites but also underscores their potential in a wide range of applications, including environmental remediation, sensing, energy storage, and optoelectronics. [ABSTRACT FROM AUTHOR]

In this study, the electrocatalytic behavior of tin sulfide doped with various metallic elements (copper, cobalt, nickel, and iron) for the oxygen reduction reaction was investigated. Our findings reveal cobalt as the most effective dopant in enhancing ORR efficiency. The graphene nanosheets were introduced to form a G/Co-SnS 2 nanocomposite, which significantly improved ORR performance, surpassing Pt/C in current density. Our findings underscore the positive impact of chemical doping and the synergistic effect of SnS 2 with graphene nanosheets, improving the onset potential and facilitating the ORR. Through comprehensive characterization including XRD, XPS, FESEM, and BET analysis, the structural and surface properties of the materials were evaluated. Employing the Rotating Disk Electrode technique, we observed that G/Co-SnS 2 exhibited a superior onset potential of 0.88 V vs. RHE and high current density of 6.12 mA cm−2, indicating enhanced ORR facilitation. Furthermore, Electrochemical Impedance Spectroscopy revealed lower resistance in the G/Co-SnS 2 nanocomposite compared to other samples, highlighting its enhanced durability. Additionally, G/Co-SnS 2 nanocomposite demonstrated significantly enhanced durability in comparison to the costly Pt/C catalyst, further underscoring its potential as a robust alternative for catalyzing the oxygen reduction reaction. These comprehensive characterizations provide insights into the enhanced electrocatalytic performance observed. Overall, this study highlights the promising potential of Co-doped SnS 2 in combination with graphene nanosheets for efficient oxygen reduction reactions, opening avenues for advanced electrocatalytic materials in energy applications. [Display omitted] [ABSTRACT FROM AUTHOR]

As well known, the electrochemiluminescence (ECL) of tris(2,2′-bipyridine)ruthenium(ii) (Ru(bpy)32+) heavily relies on highly positive or negative triggered voltage, prejudicing the detection toward the bio-molecules. In this work, Ru(bpy)32+ could generate enhanced and stable ECL at a low potential of 0.05 V (vs. Ag/AgCl) on graphene-PtPd hybrid, attributing to its excellent electrocatalysis from the synergistic effect between Pt and Pd. The obtained low-potential-driven ECL could be quenched by MoS2 nanoflowers. Based on the quenching effect, a sandwich "signal-off" ECL immunosensor was fabricated to sensitively detect carcinoembryonic antigen (CEA). A linear calibration curve from 1 fg mL−1 to 1 ng mL−1 was obtained along with a low detection limit of 0.54 fg mL−1 (S/N = 3) under optimal conditions. The sensor showed satisfactory specificity, stability, and reproducibility and was successfully applied to determine CEA in actual samples. The recoveries ranged from 98.80 to 100.23%, and the relative standard deviation (RSD) was lower than 5%. Above all, this work explored new materials in low-potential-driven ECL system and provided a reliable sensing strategy for clinical applications. [ABSTRACT FROM AUTHOR]

As well known, the electrochemiluminescence (ECL) of tris(2,2′-bipyridine)ruthenium(ii) (Ru(bpy)32+) heavily relies on highly positive or negative triggered voltage, prejudicing the detection toward the bio-molecules. In this work, Ru(bpy)32+ could generate enhanced and stable ECL at a low potential of 0.05 V (vs. Ag/AgCl) on graphene-PtPd hybrid, attributing to its excellent electrocatalysis from the synergistic effect between Pt and Pd. The obtained low-potential-driven ECL could be quenched by MoS2 nanoflowers. Based on the quenching effect, a sandwich "signal-off" ECL immunosensor was fabricated to sensitively detect carcinoembryonic antigen (CEA). A linear calibration curve from 1 fg mL−1 to 1 ng mL−1 was obtained along with a low detection limit of 0.54 fg mL−1 (S/N = 3) under optimal conditions. The sensor showed satisfactory specificity, stability, and reproducibility and was successfully applied to determine CEA in actual samples. The recoveries ranged from 98.80 to 100.23%, and the relative standard deviation (RSD) was lower than 5%. Above all, this work explored new materials in low-potential-driven ECL system and provided a reliable sensing strategy for clinical applications. [ABSTRACT FROM AUTHOR]

Under thermal environment and axial forces, the dynamic instability of functionally graded graphene platelet (GPLs)-reinforced porous beams on an elastic foundation is investigated. Three modes of porosity distributions and GPL patterns are considered. The governing equations are given by the Hamilton principle. On the basis of the differential quadrature method (DQM), the governing equations are changed into Mathieu–Hill equations, and the main unstable regions of the porous composite beams are studied by the Bolotin method. Thermal buckling and thermo-mechanical vibration problems are also studied. The effects of porosity coefficients and GPL weight fraction, dispersion pattern, initial thermal loading, slenderness ratio, geometry and size, boundary conditions, and foundation stiffness are discussed. The conclusions show that an elastic foundation has an obvious enhancement effect on thermal buckling, free vibration, and dynamic instability, which improves the stiffness of the beam.

Antibiotics determination plays a major role in minimizing antimicrobial resistance starting from quality control of pharmaceutical formulations to therapeutic drug monitoring. Green modified glassy carbon electrode has been developed for determination of tedizolid phosphate; new antibiotic prodrug; in presence of its active metabolite. The graphene transducer interlayer, dispersed with PVC, improved the electrode stability and standard potential reproducibility. Graphene hydrophobicity prevented the water layer formation between the sensing layers that decreased the potential drift down to 267 μV h−1. Electrochemical impedance showed a low resistance value for graphene containing sensor due to its high electron transfer ability. [ABSTRACT FROM AUTHOR]

Synthesis and characterization of a new class of polybutadiene polyol polyurethanes were investigated with three consecutive reactions, namely polybutadiene (PB) chain cleavage by a two-step oxidation reaction using meta-chloroperbenzoic acid (m-CPBA) and periodic acid (H5IO6) in order to prepare polybutadiene polyol precursor, continued by telechelic amine polyol synthesis by an amination reaction using diethanolamine (DEA) in the presence of sodium borohydride (NaBH4) and finally telechelic polyurethane preparation by the reaction of synthesized polyol and toluene diisocyanate (TDI). Nanocomposites were prepared through an in situ polymerization reaction by incorporation of 1–3 wt% of graphene conductive nanosheets. Successful structural elucidation of the synthesized polymeric binder and nanocomposites was investigated by using well-known methods. TGA analysis revealed slower degradation and moderate thermal stability in higher weight percent nanocomposite. SEM images and XRD patterns resulted in fine nanoparticle distribution, lack of agglomeration and approximately constant nanoparticle size. Conductometry confirmed higher electrical conductivity data for nanocomposites by increasing graphene nanosheet contents. [ABSTRACT FROM AUTHOR]

The size of graphene nanofillers and the ambient temperature are two important factors for the effective thermal conductivity of graphene nanocomposites. However, these two issues together are seldom considered in theoretical evaluation of the overall thermal property. By introducing the size-dependent thermal transport mechanisms (quasi-ballistic heat flow and diffusive heat transport) to the Landauer-like theory, we established a new method to calculate the in-plane size and temperature dependence of the thermal conductivity of graphene nanofillers from the nanoscale perspective, which is crucial for the overall thermal conductivity of the nanocomposites. The validity of this approach was confirmed by nonequilibrium molecular dynamics simulation. Then the filler-size- and temperature-dependent thermal conductivity of graphene nanocomposites was calculated via an effective-medium approximation based on Maxwell's far-field matching at a microscopic level. We highlight this multiscale approach with its implementation in the estimation of the overall thermal conductivity of graphene-polymer nanocomposites. The results are shown to be in close agreement with the experimental observations over the average filler size from 200 to 1000 nm and over the temperature from 300 to 360 K, respectively. This study revealed the significant effects of the graphene-filler size and the ambient temperature on the thermal conductivity of the nanocomposites. Image 1 [ABSTRACT FROM AUTHOR]

Nanocomposite materials can enhance the capabilities of water treatment processes such as photocatalysis. In this work, novel light-driven nanocatalysts were synthesized by using nickel ferrite (NiFe2O4) to nanoenable graphene oxide (GO) substrates. GO is an emerging 2D nanomaterial with high conductivity and adsorption properties. Moreover, the electric properties of GO improve photocatalytic performance by promoting charge carrier separation. Results of the characterization of the nickel ferrite nanoenabled graphene oxide (NiFe2O4@GO) nanocomposites demonstrate that homogeneous and stable photocatalysts were produced. The as-synthesized nanocatalysts enabled complete decolorization of the colored water matrix in short irradiation times of 150 min using minimal catalyst loading at 0.5 g L−1. The selective hook and destroy mechanism reduced the competitive effect of co-existing ions in solution. Furthermore, the use of specific scavengers helped to elucidate the degradation mechanisms of organic dye methylene blue by NiFe2O4@GO nanocomposites. [ABSTRACT FROM AUTHOR]

In this study, a nanoscale graphene oxide polymer composite drug delivery system was synthesized and investigated for possible oral delivery of doxorubicin. A doxorubicin-loaded nanocomposite composed of graphene oxide/poly(2-hydroxyethylmethacrylate)-g-poly(lactide)- b -polyethyleneglycol- b -poly(2-hydroxyethylmethacrylate)-g-poly(lactide) GO/(PHEMA-g-PLA)- b -PEG- b -(PHEMA-g-PLA) was synthesized via reversible addition fragmentation chain (RAFT) and ring open polymerization (ROP). The GO/(PHEMA-g-PLA)- b -PEG- b - (PHEMA-g-PLA) nanocomposites was characterized by scanning electron microscopy (FE-SEM), thermogravimetry (TG), ultraviolet-visible (UV–Vis) spectroscopy, and dynamic light scattering (DLS). Doxorubicin was successfully loaded into the nanocomposite with a small particle size of 51 nm and an encapsulation efficiency (EE) of 82% ±1.12%. The results showed that DOX was attached to the graphene surface via hydrophobic interactions and π-π stacking. DOX release took place under neutral and acidic conditions, reaching 24.7% and 41.2% respectively after 72 h. Cytotoxicity experiments on 4T1 murine breast cancer cells demonstrated the antitumor activity of the DOX@GO nanocomposite. Biocompatibility, cell uptake, DAPI staining, Annexin V/PI double staining, intracellular reactive oxygen species (ROS) assay, and scratch healing assay were measured. The DOX@graphene nanocomposite system could be promising for breast cancer therapy. [ABSTRACT FROM AUTHOR]

In the recent drug analysis arena, optimizing a green, eco-friendly, and cost-effective technique is the main target. In order to cope with green analytical chemistry principles and the trending development of miniaturized portable and handheld devices, an innovative microfabricated ion-selective electrode for the analysis of metoclopramide (MTP) was developed. The fabricated electrode adopted a two-step optimization process. The first step of optimization depended on screening different ionophores in order to enhance the sensor selectivity. Calix-4-arene showed the maximal selectivity towards MTP. The second step was utilizing a graphene nanocomposite as an ion-to-electron transducer layer between the calix-4-arene polymeric membrane and the microfabricated copper solid-contact ion-selective electrode. The graphene nanocomposite layer added more stability to electrode potential drift and short response times (10 s), probably due to the hydrophobic behavior of the graphene nanocomposite, which precludes the formation of a water layer at the Cu electrode/polymeric membrane interface. The proposed MTP sensor has been characterized according to IUPAC recommendations and the linear dynamic range estimated to be 1 × 10−6 to 1 × 10−2 M with LOD of 3 × 10−7 M. The proposed sensor has been successfully employed in the selective determination of MTP in bulk powder, pharmaceutical formulation, and biological fluid. No statistical significant difference was observed upon comparing the results with those of the official method. The Eco-score of the method was assessed using the Eco-Scale tool and was compared with that of the official method. [ABSTRACT FROM AUTHOR]

In this manuscript, RDX (Royal Demolition eXplosive) and HMX (High Melting eXplosive) were removed from water that is mainly polluted by military activities. Two different forms of magnetic graphene oxide nanocomposites, α-Fe2O3-rGO (hematite-reduced graphene oxide) and nZVI-rGO (nano zero valent iron-reduced graphene oxide) have been evaluated for decontamination of water containing these carcinogenic explosives. Comparative adsorption studies were carried out considering contact time, pH and adsorbent dosage for all the adsorbent–adsorbate systems. Batch adsorption experiments at varied concentrations of RDX and HMX were conducted. The experimental results better fit in pseudo second order model following Freundlich isotherm. Magnetic nature of both adsorbents is suitable for their easy separation from contaminated water in presence of an external magnetic field. α-Fe2O3-rGO showed higher adsorption capacities for HMX and RDX, this was supported by the physio-chemical properties of the adsorbent. Therefore, it could be potentially upscaled and used commercially for purification of water containing explosives. [ABSTRACT FROM AUTHOR]

Here, we report the design of a disposable single-drop voltammetric sensor for the quantitative determination of antipsychotic drug trifluoperazine (TFP). The sensor was built using inkjet-printed carbon nanotube (CNT) electrodes, which were modified with dimercaptosuccinic acid (DMSA)-coated magnetite nanoparticles uniformly dispersed over reduced graphene oxide nanosheets (DMSA/Fe3O4/RGO). The used modifying materials were characterized by electron microscopy techniques (transmission electron microscopy (TEM) and field emission-scanning electron microscopy (FE-SEM)), X-ray powder diffraction, ζ-potential measurements, dynamic light scattering (DLS), and electrochemical methods (cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS)). The developed sensor, best operated at pH 7 in the Britton–Robinson buffer solution (BRBS), shows linear electrocatalytic activity with TFP in the concentration range of 1–50 μM, a low detection limit of 0.54 μM, and excellent selectivity, repeatability, and reproducibility with an relative standard deviation (RSD) of 2.4%. A voltammetric approach using square wave voltammetry (SWV) is a sensitive technique under optimized conditions for the analytical determination of submicromolar amounts of TFP. Bare CNT and RGO- and DMSA/Fe3O4-modified CNT electrodes showed lower electrocatalytic activity than the DMSA/Fe3O4/RGO/CNT electrode. The development of this kind of TFP sensor based on nanoparticle-decorated graphene nanosheets can offer a tool for point-of-care applications as sensors in biomedicine. [ABSTRACT FROM AUTHOR]

Temperature and the alignment state of nanofillers are two important factors that can greatly affect the thermal conductivity of graphene nanocomposites, but the simultaneous influence of these two issues have never been considered in any theoretical treatment. In this work we incorporate the contributions of electron-phonon coupling and phonon-phonon interaction into the diffuse mismatch model to establish the temperature dependence of filler-matrix interfacial thermal resistance and filler-filler contact resistance, both crucial for thermal conduction in graphene nanocomposites. The electron and phonon transport mechanisms, suitable for metal and nonmetal matrices respectively, are both taken into account. Then through an effective-medium approximation based on Maxwell's far-field matching, the temperature-dependent thermal conductivity of both metal and nonmetal-based graphene nanocomposites is derived. By further introducing a confinement angle with respect to the main alignment direction wherein the graphene nanofillers are supposed to be dispersed, the influence of the alignment state of graphene nanofillers is also investigated. We highlight this newly developed theory with direct comparisons to several sets of experimental data, and demonstrate the significant effects of temperature level and alignment state in thermal conductivity of graphene metal and nonmetal nanocomposites. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Personal care products (PCPs) have a prospective influence on human health, and their vast use may cause health effects such as breast cancer. In that perspective, current study is focused on designing a porous N-doped graphene-NiO nano-composite for adsorption of PCPs. Facile, easy and green onepot synthesis via electrochemical/microwave-assisted method was applied. One family, parabens, of PCPs has been selected to be removed from water. Methyl, ethyl, propyl and butyl parabens were removed in single and competitive adsorption systems. The kinetics, thermodynamics, equilibrium, and adsorption behavior under varied pH and dosage were investigated. Recycling of exhausted adsorbent was also studied. The adsorption amount of methyl, ethyl, propyl and butyl parabens was 3.12, 5.28, 8.42 and 10.46 mg g-1 adsorbent under the optimum conditions. It was found that the process obeyed pseudo-second-order kinetic model and both Langmuir and Temkin isotherm models satisfactorily. The process was thermodynamically spontaneous and endothermic. Results revealed that the prepared adsorbent is recyclable and its removal mechanism involves hydrophobic as well as p-p interactions. [ABSTRACT FROM AUTHOR]

A novel graphene oxide nanocomposite was investigated in a flat membrane module with cross-flow pattern for decontamination of water on optimization of the operating conditions. Response surface optimization methodology was followed in arriving at the best operating conditions. The best module performance in terms of flux and rejection was obtained at the optimum set of operating conditions comprising a pH of 8.0, operating pressure of 14 bars and an hourly cross-flow of 800 L. At the end of a 96-h run, the observed drop in flux was a negligible 3.4%. On rinsing and backwashing at the end of this period, the net drop could be limited to within 2%. The module succeeded in selectively removing 98.5% of arsenic, 96.7% of fluoride, 96–97% of iron and suspended solids from contaminated groundwater while permeating more than 79–81% of the useful calcium and 87–90% of magnesium minerals as desired in potable water. The study shows that if run under properly optimized conditions, a flat membrane module with cross-flow pattern and equipped with the graphene oxide nanocomposite can be a potential technology in producing healthy, tasty and non-toxic drinking water from contaminated groundwater even in the remote areas. [ABSTRACT FROM AUTHOR]

Highlights • Uniform growth of MOF on graphene via bottom up synthesis. • MOF@G shows a billion times enhancement of MOF conductivity. • The overall porosity of the MOF@G is comparable with pristine MOF. • C-AFM is more accurate to probe the conductivity of MOF composite. • Interfacial states are most likely the main drive for conducting channels. Abstract While technologically important to maintain porosity, a noninvasive improvement and testing of electrical conductivity of metal-organic frameworks (MOFs), and their composites, are challenging due to their insulating and fragile nature. A conducting atomic force microscope (C-AFM) was utilized to probe the conductivity of self-assembled MOF on graphene (UiO-66-NH 2 @G) and compared with conventional 4-point probe method. C-AFM gives 11.8 Sm−1 for the conductivity on a single grain, while an average value of 6.6 × 10−4 Sm−1 was recorded utilizing the 4-point probe method. The dramatic enhancement of conductivity for the MOF@G composite can be ascribed to delocalization of interfacial states between MOF and graphene. Concurrently, gas sorption, X-ray and FTIR analysis reveal no changes in the overall porosity and the structure of the MOF materials. The combination of bottom up synthesis and testing provides guidelines to enhance conductivity and understand the mechanism of charge transport in otherwise insulating MOF materials. [ABSTRACT FROM AUTHOR]

Abstract We report the synthesis of Mn 3 O 4 nanostructures and their graphene composites following a novel, surfactant free, single-step hydrothermal method. The structural and morphological characterizations of graphene wrapped Mn 3 O 4 nano-octahedrons (Mn 3 O 4 -rGO) are carried out using powder X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, Field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). We study the electrochemical properties of as-prepared Mn 3 O 4 and Mn 3 O 4 -rGO composite as anodes for lithium ion batteries (LIBs). Mn 3 O 4 -rGO composite electrode showed excellent electrochemical properties when cycled against Li/Li+, with a reversible specific capacity of 474 mAh g−1 at 100 mA g−1 upon 200 cycles. Further, we investigate the kinetics behavior of these electrodes and study their capacitive contribution towards total charge storage. With a high capacitive contribution of ∼73% at 1.0 mV s−1, Mn 3 O 4 -rGO composite electrode exhibits excellent potential for their application in lithium ion battery and hybrid lithium ion capacitor devices. Graphical abstract Image 1 Highlights • One-step synthesis of Mn 3 O 4 /rGO composite with unique morphology is demonstrated. • Mn 3 O 4 /rGO composite electrode exhibits enhanced electrochemical properties. • Excellent Li-ion kinetics is shown with a capacitive nature of ∼73% at 1.0 mV s−1. • Mn 3 O 4 /rGO composite electrode shows potential as efficient anode for LIBs. [ABSTRACT FROM AUTHOR]

Despite significant interest in developing extracellular matrix (ECM)‐inspired biomaterials to recreate native cell‐instructive microenvironments, the major challenge in the biomaterial field is to recapitulate the complex structural and biophysical features of native ECM. These biophysical features include multiscale hierarchy, electrical conductivity, optimum wettability, and mechanical properties. These features are critical to the design of cell‐instructive biomaterials for bioengineering applications such as skeletal muscle tissue engineering. In this study, we used a custom‐designed film fabrication assembly, which consists of a microfluidic chamber to allow electrostatic charge‐based self‐assembly of oppositely charged polymer solutions forming a hydrogel fiber and eventually, a nanocomposite fibrous hydrogel film. The film recapitulates unidirectional hierarchical fibrous structure along with the conductive properties to guide initial alignment and myotube formation from cultured myoblasts. We combined high conductivity, and charge carrier mobility of graphene with biocompatibility of polysaccharides to develop graphene–polysaccharide nanocomposite fibrous hydrogel films. The incorporation of graphene in fibrous hydrogel films enhanced their wettability, electrical conductivity, tensile strength, and toughness without significantly altering their elastic properties (Young's modulus). In a proof‐of‐concept study, the mouse myoblast cells (C2C12) seeded on these nanocomposite fibrous hydrogel films showed improved spreading and enhanced myogenesis as evident by the formation of multinucleated myotubes, an early indicator of myogenesis. Overall, graphene–polysaccharide nanocomposite fibrous hydrogel films provide a potential biomaterial to promote skeletal muscle tissue regeneration. Self‐assembly of sonicated graphene–chitosan and gellan gum solutions in a microfluidic chamber produces nanocomposite polysaccharide–graphene hydrogel fibers. Parallel arrangement of multiple fibers makes a bioinspired film with multiscale hierarchy. These films promote differentiation of myoblasts into multinucleated myotube. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Highly active tin doped zirconia/graphene nanocomposite was successfully prepared. • Synthesis of DMC was catalysed by a novel Zr–Sn–O/GO nanocomposite catalyst. • This method produced 82.4% PC conversion and 78.2% yield of DMC. • Novel catalyst was reused several times without affecting its catalytic performance. • Experimental and model predicted values showed an excellent agreement. Abstract A green, rapid and continuous hydrothermal flow synthesis (CHFS) route has been employed to synthesise highly efficient and active novel heterogeneous catalysts. Tin doped zirconia (Zr–Sn–O) and tin doped zirconia/graphene nanocomposite (Zr–Sn/GO) have been assessed as suitable heterogeneous catalysts for the synthesis of dimethyl carbonate (DMC). The catalysts have been extensively characterized using powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area measurement and X-ray photoelectron spectroscopy (XPS) analysis. Extensive batch studies for the synthesis of DMC via the transesterification of propylene carbonate (PC) and methanol (MeOH) using Zr–Sn/GO catalyst in a solvent free process were also conducted. The effect of various reaction conditions such as reactant molar ratio, catalyst loading, reaction temperature and reaction time has been extensively evaluated. Response surface methodology based on Box-Behneken Design (BBD) was employed to derive optimum conditions for maximising PC conversion and DMC yield. The correlations and interactions between various variables such as MeOH:PC ratio, catalyst loading, reaction temperature, reaction time and stirring speed were extensively studied. A quadratic model by multiple regression analysis for the PC conversion and DMC yield was developed and verified by several methods BBD revealed that optimum conditions for high yield values of DMC are 12.33:1 MeOH:PC molar ratio, 446.7 K, 4.08 h and 300 rpm using 2.9% (w/w) Zr–Sn/GO nanocomposite. The maximum predicted responses at the optimum conditions are 85.1% and 81% for PC conversion and yield of DMC respectively. Experimental results at optimum model predicted reaction conditions agree very well with the model predicted response, where 82.4% PC conversion and 78.2% yield of DMC were obtained. Catalyst reusability and stability studies have been conducted at optimum reaction condition to investigate the long term stability of Zr–Sn/GO and it has been found that the catalyst could be reused more than six times (about 42 h) without losing its catalytic activity. These experimental and model predicted values showed an excellent agreement for tin doped zirconia/graphene nanocomposite as a heterogeneous catalyst for the synthesis of DMC from PC and MeOH. [ABSTRACT FROM AUTHOR]

For the first time, a simple and rapid sonochemical technique for preparing of pure Cd 2 SiO 4 nanostructures has been developed in presence of various surfactants of SDS, CTAB and PVP. Uniform and fine Cd 2 SiO 4 nanoparticle was synthesized using of polymeric PVP surfactant and ultrasonic irradiation. The optimized cadmium silicate nanostructures added to graphene sheets and Cd 2 SiO 4 /Graphene nanocomposite synthesized through pre-graphenization. Hydrogen storage capacity performances of Cd 2 SiO 4 nanoparticle and Cd 2 SiO 4 /Graphene nanocomposite were compared. Obtained results represent that Cd 2 SiO 4 /Graphene nanocomposites have higher hydrogen storage capacity than Cd 2 SiO 4 nanoparticles. Cd 2 SiO 4 /Graphene nanocomposites and Cd 2 SiO 4 nanoparticles show hydrogen storage capacity of 3300 and 1300 mAh/g, respectively. [ABSTRACT FROM AUTHOR]

In order to improve the electrochemical properties of LaMnO 3 perovskite (LMO) materials for supercapacitor applications, different amount of nitrogen-doped reduced graphene oxide (N-rGO) from 25 to 75 wt % has been incorporated with LMO to form nanocomposite materials. These three-dimensional structures are assembled through electrostatic attraction of the positive charged N-rGO and the negative charged LMO. The amount of N-rGO has a significant effect on the properties of the composite materials. Microscopic investigations confirm that LMO particles are wrapped by N-rGO sheets, and with the increase of N-rGO content, the dispersion of LMO particles in graphene matrix is enhanced. Electrochemical characterizations reveal that the specific capacitance of the nanocomposites has been dramatically improved. Compared with pristine graphene and LMO, the sample with a lower amount of N-rGO (25%) exhibited the highest specific capacitance (687 Fg −1 at 5 mVs −1 ) and the longest stability (79% retention after 2000 cycle at 10 Ag −1 ) among other composite materials. The superior capacitive properties make LMO/N-rGO nanocomposites stand out as a promising candidate for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Graphical Flow chart for the synthesis of Cu-colloid-based nanoparticles. [Display omitted] • Copper nanoparticles were synthesized through the colloidal and solution combustion method, and their electrochemical properties were evaluated using three electrode systems to detect glucose content. • The colloidal method yields Cu-Colloid nanoparticles that have a homogenous phase and a flower-like structure. • A glucose biosensor was then fabricated using the developed colloidal copper nanoparticles modified with graphene-coated on indium-coated tin oxide (ITO) glass substrate (Flower shaped-CuO/G/ITO) as a working electrode. • The lower detection limit of 1 µmol L−1, the sensitivity of 1610 µA mM−1 cm−2, and the linear range of 1 µM to µ850 M at an applied potential of +0.60 V vs. Ag/AgCl were obtained for the developed nanocomposite electrode. • The developed bioelectrode shows good stability, and reproducibility with less response time making it a promising electrode for developing a non-enzymatic glucose biosensor. In this work, copper nanoparticles were synthesized through the colloidal and solution combustion method, and their electrochemical properties were evaluated using three electrode systems to detect glucose content. The solution combustion method using the fuels glycine (Gly) and hydrazine (Hyd) produces nanoparticles with amorphous spherical forms and a small flake-like structure. The colloidal method yields Cu-Colloid nanoparticles that have a homogenous phase and a flower-like structure with high electro-oxidative current due to the large surface area of the developed nanoparticle which is in contact with the glucose. A glucose biosensor was then fabricated using the developed colloidal copper nanoparticles modified with graphene-coated on indium-coated tin oxide (ITO) glass substrate (Flower shaped-CuO/G/ITO) as a working electrode. The copper nanoparticles were characterized by an X-ray diffractometer, UV–VIS spectrometer, Transmission, and Scanning electron microscope for crystalline, morphological, surface studies with 10–20 nm in diameter, 280–310 nm absorption range, and energy bandgap of 1.45ev. The lower detection limit of 1 μmol L−1, the sensitivity of 1610 μA mM−1 cm−2, and the linear range of 1 μMto μ850 M at an applied potential of +0.60 V vs. Ag/AgCl was obtained for the developed nanocomposite electrode. The developed bioelectrode shows good stability and reproducibility with less response time making it a promising electrode for developing a non-enzymatic glucose biosensor. [ABSTRACT FROM AUTHOR]

The present work focused on electromagnetic (EM) absorption performance comparison of different polymer nanocomposite structures. Synthesis and fabrication of polymer nanocomposite composed of graphene, polyurethane (PU), epoxy was done using in situ polymerization and resin transfer moulding respectively. The effect of polymer on EM properties of composite was carried out using waveguide measurement technique in X-band. Reflection Loss (RL) and shielding effectiveness (SE) were measured for various nanocomposites using EM wave theory. From the results it is observed that 2.5 wt% of PU/epoxy graphene nanocomposite has shown RL value −35 dB at 12.1 GHz and SE value of −45 dB.

A facile and eco-friendly self-assembly method for combining mesoporous silica with Cu 2 O-graphene composite with a nonionic surfactant Pluronic® P123 is proposed. The achieved nanocomposites were characterized via X-ray diffraction (XRD), nitrogen adsorption/desorption isotherms using the BET and BJH method, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectroscopy (XPS), and FT-IR spectra. The photocatalytic degradation of safranine O (SO), texbrite BA-L (TBA), texbrite NFW-L (TNFW), and texbrite BAC-L (TBAC) organic dyes in an aqueous solution under visible light irradiation with the difference of initial pH and catalyst dosage was observed via UV spectrophotometry, after measuring the decrease in their concentrations. Two factors of the excellent photocatalytic activity of the mesoporous SiO 2 /Cu 2 O-graphene composite made a significant impression: the adsorption capacity due to the mesoporous structure (a result of the pore diameter, pore volume, and large surface area), and the decomposition effect through catalysis. Recycling experiments that were also carried out proved the good stability of the survey samples. The combination of mesoporous SiO 2 with 10% Cu 2 O-graphene nanocomposite (by weight) is expected to become a new generation material for photodegradation with excellent performance. [ABSTRACT FROM AUTHOR]

A novel binary nanocomposite, ZnO/nitrogen-doped graphene (ZnO/NG), is synthesized via a facile solution method. In this prepared ZnO/NG composite, highly-crystalline ZnO nanoparticles with a size of about 10 nm are anchored uniformly on the N-doped graphene nanosheets. Electrochemical properties of the ZnO/NG composite as anode materials are systematically investigated in lithium-ion batteries. Specifically, the ZnO/NG composite can maintain the reversible specific discharge capacity at 870 mAh g−1 after 200 cycles at 100 mA g−1. Besides the enhanced electronic conductivity provided by interlaced N-doped graphene nanosheets, the excellent lithium storage properties of the ZnO/NG composite can be due to nanosized structure of ZnO particles, shortening the Li+ diffusion distance, increasing reaction sites, and buffering the ZnO volume change during the charge/discharge process. [ABSTRACT FROM AUTHOR]

This paper investigates the parametric instability of functionally graded graphene reinforced nanocomposite plates that undergo a periodic uniaxial in-plane force and a uniform temperature rise. The plate is composed of multiple graphene platelet reinforced composite (GPLRC) layers in which graphene platelets (GPLs) are uniformly distributed in each individual layer with GPL concentration varying layer-wise across the plate thickness. The modified Halpin–Tsai model that takes into account the GPL geometry effect is employed to calculate the Young's modulus of the GPLRC. Based on the first-order shear deformation theory, the governing equations are deduced and then are solved by using the differential quadrature approach integrated with the Bolotin's method. A parametric study is undertaken to show the influences of GPL distribution pattern, concentration and geometry, temperature change, static in-plane force, plate geometry and boundary condition on the parametric instability of functionally graded multilayer GPLRC plates. It is found that the addition of a small amount of GPL reinforcements considerably increases the critical buckling load and natural frequencies but reduces the size of unstable region. The reinforcing effect is the best when the surface layers of the plate are GPL-rich. [ABSTRACT FROM AUTHOR]

This paper deals with the thermal buckling and postbuckling of functionally graded multilayer nanocomposite plates reinforced with a low content of graphene platelets (GPLs). It is assumed that GPL reinforcements are randomly oriented and uniformly dispersed in each individual GPL-reinforced composite (GPLRC) layer but the concentration follows a layer-wise variation across the plate thickness. The modified Halpin-Tsai micromechanics model that takes into account the GPL geometry effect is adopted to estimate the effective Young's modulus of GPLRC layers. Within the framework of the first-order shear deformation theory, the nonlinear governing equations are derived by applying the principle of virtual displacements and then solved by using a differential quadrature-based iteration technique. Parametric studies are conducted to examine the influences of GPL distribution pattern, concentration and geometry, as well as in-plane force on the thermal buckling and postbuckling behaviours. Our results show that distributing more GPLs near the surface layers is capable of reinforcing the thermal buckling and postbuckling performances of GPLRC plates. Whether the thermal buckling and postbuckling resistance increases or decreases with the increases in GPL weight fraction, aspect ratio and width-to-thickness ratio is highly dependent on the GPL distribution pattern. [ABSTRACT FROM AUTHOR]

A novel material, frost-like CuO combined-graphene-TiO 2 composite, was successfully synthesized using a self-assembly method. During the reaction, the loading of CuO and TiO 2 nanoparticles on graphene sheets was achieved. The obtained CuO-graphene-TiO 2 composite photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), and X-ray photoelectron spectroscopy (XPS). The frost-like CuO nanoparticles combined with the small TiO 2 rods were successfully loaded on the transparent graphene sheets. The photocatalytic degradation of rhodamine B (RhB), methylene blue trihydrate (MB), and reactive black B (RBB) in an aqueous solution under visible light irradiation was observed by UV spectrophotometry after measurement of the decrease of their concentrations. Through the photocatalytic test and TOC results, the CuO-graphene-TiO 2 is expected to become a new potential material for photodegradation activity with excellent photodegradation. The scavenging experiments confirmed that OH and h + play a major role in the photocatalytic reaction than O 2 − or both hydroxyl and holes are the active species responsible for the RBB degradation under visible light irradiation. After five repeated cycles to investigate the stability of photocatalytic performance, the CuO-graphene-TiO 2 had high stability under visible light irradiation. [ABSTRACT FROM AUTHOR]

Beta-cyclodextrin capped Graphene-magnetite (G-Fe 3 O 4 -BCD) nanocomposite was synthesized by ethylenediamine conjugation and used as an adsorbent for selective removal of Bisphenol-A (BPA) in water. Characterization of nanocomposite revealed BCD conjugated to Fe 3 O 4 nanoparticles (30–40 nm) embedded on graphene. Adsorption process followed Langmuir model and pseudo second order kinetics with an adsorption capacity of 59.6 mg/g. It was found to be highly favourable physisorption and endothermic process as indicated by ΔG ° (−3.36 kJ/mol) and ΔH ° (2.08 kJ/mol) values at ambient temperatures. The nanocomposite was highly specific towards BPA compared to its analogs, largely driven by host-guest interaction between BCD and BPA. Nanocomposite had a high magnetization of 97 emu/g with superparamagnetic property at room temperature which helps in faster separation using an external magnetic field. Nanocomposite can be regenerated with methanol and can be reused without much loss in adsorption efficiency (<10%) after 6 cycles. It has huge potential and application in selective adsorption of target molecules. [ABSTRACT FROM AUTHOR]

For the first time, a novel technique of preparing Zn 2 GeO 4 nanostructures has been developed by using chemical precipitation method of GeCl 4 as a Ge precursor and acacen as a capping agent. Uniform and fine Zn 2 GeO 4 nanoparticle was synthesized. The optimized Zn 2 GeO 4 nanostructures anchored onto graphene sheets and Zn 2 GeO 4 /graphene nanocomposite synthesized through pre-graphenization, successfully. Hydrogen storage capacities of Zn 2 GeO 4 nanoparticle and Zn 2 GeO 4 /graphene nanocomposite were compared, for the first time. Obtained results represent that Zn 2 GeO 4 /graphene nanocomposites have higher electrochemical hydrogen storage capacity than Zn 2 GeO 4 nanoparticles. It was found that the synergistic effect between Zn 2 GeO 4 nanoparticles and graphene sheets can improve the electrochemical performance of this hybrid composite electrode. After 29 cycles, the discharging capacities of the electrode reached to 2695 mAh/g. These results indicate that the Zn 2 GeO 4 /graphene nanocomposite can be potentially applied for electrochemical hydrogen storage. [ABSTRACT FROM AUTHOR]