Graphene Carbon Nanotubes Research Articles

Recent Advances in Synthesising and Applying Magnetic Ion-Imprinted Polymers to Detect, Pre-Concentrate, and Remove Heavy Metals in Various Matrices

Magnetic ion-imprinted polymers (MIIPs) are an innovative material that combines the selectivity of ion imprinting with the ease of separation provided by magnetic properties. Recent advancements in MIIPs have shown that they have higher selectivity coefficients compared to non-imprinted materials. The synthesis of MIIPs involves creating specific recognition sites for target ions in magnetic nanomaterials. Various nanomaterials, such as graphene oxide, carbon nanotubes, and silica, have been incorporated into the IIPs to improve their analytical performance for different environmental applications, including metal extraction, monitoring, detection, and quantification. This review stresses the need to develop new monomers with a high affinity for the target analyte and to find supporting materials with groups that facilitate the effective removal of the target analyte. It also explores the influence of experimental parameters on metal determination.

Influence of Reduced Graphene Oxide and Carbon Nanotubes on the Structural, Electrical, and Photoluminescent Properties of Chitosan Films.

Chitosan is a biopolymer with unique properties that have attracted considerable attention in various scientific fields in recent decades. Although chitosan is known for its poor electrical and mechanical properties, there is interest in producing chitosan-based materials reinforced with carbon-based materials to impart exceptional properties such as high electrical conductivity and high Young's modulus. This study describes the synergistic effect of carbon-based materials, such as reduced graphene oxide and carbon nanotubes, in improving the electrical, optical, and mechanical properties of chitosan-based films. Our findings demonstrate that the incorporation of reduced graphene oxide influences the crystallinity of chitosan, which considerably impacts the mechanical properties of the films. However, the incorporation of a reduced graphene oxide-carbon nanotube complex not only significantly improves the mechanical properties but also significantly improves the optical and electrical properties, as was demonstrated from the photoluminescence studies and resistivity measurements employing the four-probe technique. This is a promising prospect for the synthesis of new materials, such as biopolymer films, with potential applications in optical, electrical, and biomedical bioengineering applications.

Performance of carbon nanomaterials incorporated with concrete exposed to high temperature

Abstract In recent decades, there have been initiatives to incorporate carbon nanomaterials (CNMs) into cement composites, particularly graphene oxide (GO), carbon nanotubes, graphite (GP), and mild carbon (MC). Nevertheless, little is known about how these CNMs interact with the cement matrix itself. In this research, the impact of CNM incorporation at high temperatures (250, 500, 750, and 1,000°C) on cement’s mechanical characteristics and microstructure was investigated. Nine mixes were created with the CNM content (0.1 and 0.3%) being taken into consideration. The microstructure of the CNM composites was further investigated using X-ray diffractometry, thermogravimetry, derivative thermogravimetry, digital microscopy, and micro-computed tomography (micro-CT). Based on research observations, the study demonstrated that the mechanical properties of most specimens could be enhanced through the introduction of CNMs. The recommended proportions of GP-0.1, GO-0.1, and MC-0.1, in accordance with the weight of the binder, and the impact of the CNMs on the elastic modulus were also assessed. As a consequence, the CNM’s porous structure and apparent crack pattern were identified using microstructure analysis.

Design and Simulation of New High Speed, Low Power D-Flip-Flops, Implemented Using Graphene Nanoribbon and Carbon Nanotube Field Effect Transistors

Design and Simulation of New High Speed, Low Power D-Flip-Flops, Implemented Using Graphene Nanoribbon and Carbon Nanotube Field Effect Transistors

Enabling long cycle aluminum-sulfur batteries via structurally stable Co, N-doped graphene-CNTs covalently bonded hybrid

Al-S batteries offer advantages such as high energy density, low cost, and good safety. However, they face challenges including poor sulfur conductivity, volume expansion, and slow kinetics of polysulfides, leading to rapid capacity decay and short cycle life. Therefore, the design of materials with high conductivity, capable of anchoring polysulfides, and structurally robust is crucial for enhancing the overall performance of Al-S batteries. To address these issues, we propose the construction of a structurally stable graphene-carbon nanotubes (CNTs) covalently bonded hybrid and a three-dimensional (3D) conductive framework catalyzed by Co active sites. The porous Co, N-doped graphene-carbon nanotubes (CoN-GC) hybrid with excellent mechanical properties provides sufficient space for high sulfur loading, alleviating sulfur volume expansion. Co plays a key role in rapidly transporting electrons, adsorbing, and catalyzing aluminum polysulfides. The Al-S battery using S@CoN-GC cycles over 1500 cycles at a current density of 300 mA·g−1, maintaining a specific capacity of 315 mAh·g−1, and retains 278 mAh·g−1 after 2000 cycles. Additionally, utilizing the outstanding mechanical properties of CoN-GC, a flexible Al-S microbattery was successfully fabricated, maintaining a capacity retention of 90 % after folding 1000 times. These research findings are expected to accelerate the study of multivalent metal-sulfur batteries and their practical applications in various scenarios.

Flexible conductive polymer composite film with sandwich-like structure for ultra-efficient and high-stability electromagnetic interference shielding

Flexible electromagnetic interference (EMI) shielding films with the merits of light-weight, flexibility, and high EMI shielding performance are the essential materials for the consumer electronics and communication products. Herein, we construct a hybrid conductive network based on the electrospinning thermoplastic polyurethane (TPU) film loaded with different dimensional conductive fillers, including 0D FeCl3, 1D carbon nanotube (CNT) and 2D graphene nanosheet (GN) to achieve a flexible, light-weight, and ultra-efficient EMI shielding composite film. In specific, the electrospinning porous TPU film is firstly anchored by CNTs assisted by ultrasound to generate the porous TPU/CNT film. Thereafter, the as-prepared porous TPU/CNT film is loaded a GN/CNT/FeCl3 layer by vacuum-assisted filtration to generate a double-layer GN/CNT/FeCl3@TPU/CNT film. Finally, another porous TPU/CNT film is sealed onto the GN/CNT/FeCl3@TPU/CNT film by hot-pressing, which fabricates a sandwiched TPU/CNT@GN/CNT/FeCl3@TPU/CNT composite film. It is interesting to note that the composite film possesses the ultrahigh EMI shielding value (56.0 dB at 10.0 GHz) in the X-band (8.2–12.4 GHz) with high flexibility, excellent mechanical properties, long-term durability (acid-base environment resistance and stability after 1000 bends), as well as high thermal conductivity (6.53 W/(m.K)). This work proposes a simple but efficiency strategy to design the flexible EMI shielding film with ultra-high performance and outstanding durability.

Highly sensitive tetracycline detection using a triple amplification aptasensor based on graphene-carbon nanotube, Exonuclease I, and gold nanoprobes

Enhancing the sensitivity of targeted substance detection is crucial, yet prior research seldom incorporates more than two signal amplification methods. In this study, we introduced a novel triple signal amplification strategy for tetracycline detection using an aptasensor. This strategy integrates a graphene and multi-walled carbon nanotubes composite (GO-MWCNTs), Exonuclease I (Exo I), and a hybrid DNA-gold nanoparticle (AuNPs)-horseradish peroxidase (HRP) system. The GO-MWCNTs serve as a conductive carrier, boosting electron transfer for initial signal amplification. Exo I, targeting single-stranded DNA, facilitates target recovery and secondary signal amplification. The gold nanoprobe, through specific base pairing, binds to the tetracycline aptamer’s complementary chains on the electrode surface. Horseradish peroxidase’s catalytic action then generates a robust electrochemical signal, culminating in three-stage signal amplification. This optimized approach achieved a low detection limit of 3.3 × 10−4 ng mL−1, with a range from 1 × 10−3 ng mL−1 to 1 × 103 ng mL−1. Notably, the aptasensor demonstrated high selectivity, repeatability, stability, and reliability. These findings offer a promising reference for developing effective aptasensors in antibiotic detection.

Electrical and structural behavior of copper nanocomposites encapsulated with modified graphene oxide graft and carbon nanotubes (cu@GO-g-CNTO-amine/PCA) on copper pieces

In this study, nanocomposite coating of encapsulated copper is developed among the branches of carbon nanostructures (graphene oxide graft and carbon nanotube oxide (GO-g-CNTO)) functionalized with poly citric acid and urea on copper electrode by electrodeposition method. Increasing the percentage of Cu@GO-g-CNTO-amine/PCA nanocomposite in the electrolyte affected the surface morphology and improved the granularity of the coated copper particles. The uniform distribution of particles on the surface increased the electrical properties, current density, strength, and other properties because the improvement of the structural factors controls the mechanical behavior of the parts. The structure of the coatings and their performance were investigated by Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray energy diffraction spectroscopy (EDX), and Atomic force microscopy (AFM). The results show that by modifying the surface of carbon nanostructures with poly citric acid and urea, in addition to increasing their solubility, the thickness of the copper coating can be controlled. The use of urea in the reaction reduced the corrosion and oxidation of the surface and increased the electrical and mechanical properties of the surface.

CoS2/carbon network flexible film with Co-N bond/π-π interaction enables superior mechanical properties and high-rate sodium ion storage

Flexible electrodes based on conversion-type materials have potential applications in low-cost and high-performance flexible sodium-ion batteries (FSIBs), owing to their high theoretical capacity and appropriate sodiation potential. However, they suffer from flexible electrodes with poor mechanical properties and sluggish reaction kinetics. In this study, freestanding CoS2 nanoparticles coupled with graphene oxides and carbon nanotubes (CoS2/GO/CNTs) flexible films with robust and interconnected architectures were successfully synthesized. CoS2/GO/CNTs flexible film displays high electronic conductivity and superior mechanical properties (average tensile strength of 21.27 MPa and average toughness of 393.18 KJ m−3) owing to the defect bridge for electron transfer and the formation of the π–π interactions between CNTs and GO. In addition, the close contact between the CoS2 nanoparticles and carbon networks enabled by the Co-N chemical bond prevents the self-aggregation of the CoS2 nanoparticles. As a result, the CoS2/GO/CNTs flexible film delivered superior rate capability (213.5 mAh g−1 at 6 A g−1, better than most reported flexible anode) and long-term cycling stability. Moreover, the conversion reaction that occurred in the CoS2/GO/CNTs flexible film exhibited pseudocapacitive behavior. This study provides meaningful insights into the development of flexible electrodes with superior mechanical properties and electrochemical performance for energy storage.

Analytical modeling of nucleation and growth of graphene layers on CNT array and its application in field emission of electrons

Carbon Nanotube (CNT) arrays and graphene have undergone several investigations to achieve efficient field emission (FE) owing to CNT’s remarkable large aspect ratio and graphene’s exceptional FE stability. However, when dense CNT arrays and planar graphene layers were used as field emitters, their field enhancement factor reduced dramatically. Therefore, in this paper, we numerically analyze the growth of a dense CNT array with planar graphene layers (PGLs) on top, resulting in a CNT-PGL hybrid and the associated field enhancement factor. The growth of the CNT array is investigated using Plasma Enhanced Chemical Vapor Deposition (PECVD) chamber in C2H2/NH3 environment with variable C2H2 flow, Ni catalyst film thickness, and substrate temperature followed by PGL precipitation on its top at an optimized cooling rate and Ni film thickness. The analytical model developed accounts for the number density of ions and neutrals, various surface elementary processes on catalyst film, CNT array growth, and PGLs precipitation. According to our investigation, the average growth rate of CNTs increases and then decreases with increasing C2H2 flow rate and catalyst film thickness. CNTs grow at a faster rate when the substrate temperature increases. Furthermore, as the chamber temperature is lowered from 750 °C to 250 °C in N2 environment and Ni film thickness grows, the number of the graphene layers increases. The field enhancement factors for the CNT array and hybrid are then calculated based on the optimal parameter values. The average height of the nanotubes, their spacing from one another, and the penetration of the electric field due to graphene coverage are considered while computing the field enhancement factor. It has been found that adding planar graphene layers to densely packed CNTs can raise its field enhancement factor. The results obtained match the current experimental observations quite well.

Numerical assessment of viscoelastic tetra hybrid nanofluid flow across a stretchable rotatory disk under the Soret and Dufour aspects

PurposeFluid flows through rotatory disks are encountered in industrial and practical engineering processes, such as computer storage devices, gas turbine rotators, rotating machinery, air cleaning machines, etc. The primary purpose of this research is to examine the combined aspects of variable electrical conductivity, thermal radiation, Soret and Dufour effects on a magnetohydrodynamic Maxwell single-walled carbon nanotubes–graphene oxide–multi-walled carbon nanotubes–copper (SWCNT–GO–MWCNT–Cu)/sodium alginate tetra-hybrid nanofluid flow through a stretchable rotatory disk.Design/methodology/approachThe modeled administrative equations of the present flow problem are converted to a non-dimensional system of ordinary differential equations by applying suitable similarity conversion and then solved numerically by implementing the bvp4c method. The impressions of noteworthy dimensionless parameters on velocity, temperature, concentration distributions, Nusselt number, skin friction and Sherwood number are reported via graphs and tables.FindingsThe authors figured out that the developed values of the rotation parameter diminish the temperature but enhance both the radial and angular velocities. Further, the mass and heat transmission rates are better for tetra-hybrid nanofluids than for ternary and hybrid nanofluids.Originality/valueThe present study emphasizes a special type of fluid called the tetra-hybrid nanofluid. The existing literature has not discussed the Maxwell tetra hybrid nanofluid flow through a stretchable rotatory disk with variable electrical conductivity. Besides, the novel aspects of magnetohydrodynamics, thermal radiation, Soret and Dufour effects are also incorporated into the present flow problem.

A highly sensitive electrochemical sensor based on surface molecularly imprinted polymers and graphene carbon nanotubes for highly selective detection of chlorpyrifos

AbstractPesticide residues represent a serious challenge for environmental protection, food safety, and public health. Addressing this challenge, this study strategically developed an electrochemical sensor with molecularly imprinted polymers (MIPs) as the recognition element to accurately detect chlorpyrifos in environmental samples. In this study, we used vinyl‐modified SiO2 as the matrix, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross‐linker, and azobisisobutyronitrile as the initiator to synthesize the surface‐imprinted polymers. The development of the electrochemical sensor involved a detailed modification of the electrode, first by integrating carboxylated multi‐walled carbon nanotubes and graphene oxide to improve its properties, and then by applying a suspension of MIPs to the glassy carbon electrode. This process resulted in a sensor capable of detecting chlorpyrifos in environmental samples with high sensitivity. The electrochemical sensor, designed for chlorpyrifos detection, exhibited a robust linear response in peak current to varying concentrations of chlorpyrifos, ranging from 1 × 10−11 to 1 × 10−5 mol L−1. It achieved a detection limit as low as 1.85 × 10−11 mol L−1 (S/N = 3). Testing confirmed the sensor's exceptional repeatability, stability, and high selectivity towards chlorpyrifos, underscoring its efficacy. The demonstrated capabilities of this sensor suggest its substantial potential for widespread use in pesticide regulation and environmental conservation efforts.

Combination of core-shell structured NH2-UiO-66@ZIF-8 loaded Ru (bpy)3 2+ and molecularly imprinted copolymer for the sensitive ECL detection of tetracycline.

A molecularly imprinted electrochemiluminescent sensor is developed for the sensitive detection of tetracycline in environmental and food samples. The sensor uses an ionic liquid (i.e. [APMIM]Br) modified graphene-carbon nanotube composite (GMI) material as substrate, a double-layered core-shell metal-organic framework NH2-UiO-66@ZIF-8 (NUZ) loaded bipyridyl ruthenium (NUZ@Ru) as luminescent material, and a molecularly imprinted copolymer of o-phenylenediamine and hydroquinone as recognition element. The ionic liquid-modified graphene-carbon nanotube composite has a favorable three-dimensional structure, high specific surface area, and good hydrophilicity; the core-shell structured metal-organic framework has high stability and plentiful reaction sites for loading; the molecularly imprinted copolymer film has enhanced stability and recognition effect. Hence, the resulting sensor combines the merits of several materials and presents improved performance. Under the optimum detection conditions, it shows a wide linear range of 0.05 µM - 1 mM, a low detection limit of 20 nM, high selectivity, and excellent stability. It has been successfully applied to the detection of tetracycline in different samples.

The improvement of hydrogen storage capacity via bubbles nucleated in ice-like nanotubes

The existing methods of hydrogen storage bottlenecked advancements in its commercialization on an industrial scale. Here, the hydrogen storage capacity via the hydrogen clathrate hydrate in ice Ih (HCHinIh) with the aid of nanobubbles is further improved to 3.442–3.494 wt% from the previous 3.441 wt%. These nanobubbles are designedly arranged within 0.5 mm diameter individual ice spheres which initially pack in simple cubic form, and then used to synthesize the hydrogen clathrate hydrate as does HCHinIh. The total volume of nanobubbles is adjustable by deploying their different space layouts. In addition, we propose that the bubble formation is driven by transforming the pre-melted quasi-liquid layer (PMQLL) to solid ice-like in an ice-like nanotube, which is a structure comprised of PMQLL and ice surrounding PMQLL (PMQLL-ice) analogous to a carbon nanotube-graphene sheet (CNT-GS) structure, where the interaction energy related to O–O and O–H in PMQLL-ice is 0.08–6.17 times that of C–O and C–H in the CNT-GS structure.

Binary Co3S4/SnS chalcogenide composites anchored on graphene oxide and carbon nanotubes as anodes for Na-ion batteries

Hetero-architectures are smart for modern energy storage appliances owing to fast charge transportation. However, the smooth and rational assembly with adequate Na+ storage kinetics so far is a significant challenge. Herein, transition-bimetallic sulfides hetero-structured Co3S4/SnS (CTS) and its composites implanted in reduced graphene oxide (CTS.rGO) and carbon nanotubes (CTS.CNTs) have been synthesized and employed as anodes for sodium-ion batteries. The use of highly conductive nature of carbon frames benefits the stability and conductivity of the bimetallic sulfides CTS composites. As a result, the CTS.CNTs delivered a charge capacity 298 mAh/g, whereas CTS.rGO and bare CTS exhibited 229 and 76 mAh/g after 200cycles at 0.05C. In addition, the CTS.CNTs and CTS.rGO displayed excellent rate performance at different rates (0.05C – 10.0C) and upon reversing the C-rate to 0.05C, CTS.CNTs fully restored the charge capacity 329 mAh/g while CTS.rGO restored to 293 mAh/g. The ultra-cyclic stability and improved rate performance enlightening the synergistic effect between CTS and carbon conducting agents. Moreover, the CTS.CNTs displayed the lowest charge transfer resistance (Rct = 604 Ω) as compared to CTS.rGO and bare CTS (Rct = 618 Ω, Rct = 642 Ω), indicating the rapid charge transport.

Nanocarbon architecture-intervened interface design of Cu matrix composites towards necking-delayed fracture and toughening

In-situ formed interfacial carbides always sacrifice the structure integrity of reinforcement in nanocarbon/metal composites. Herein, leaf-like carbon nanotube-graphene nanoribbon (CNT-GNR) hybrids, consisting of CNT midrib and GNR margin, was synthetized to solve the above dilemma in nanocarbon-CuCr system. Results demonstrate that high-density nano-sized Cr7C3, which had specific orientation relationship related to the CuCr matrix ([0 0 1]Cr7C3//[011]CuCr, (2‾ 20) Cr7C3//(11 1‾)CuCr), was in-situ formed at GNR-Cu interface via “heterogeneous nucleation-growth” pattern. Meanwhile, the integrity of CNT midrib was well-retained. In-situ SEM tensile results show that such designed interface effectively prevents crack propagation, makes crack blunt via coordinated plastic deformation of local matrix, and guarantees the failure of CNT-GNR by breakage mode, being crucial for exerting the toughening and promoting strength-ductility synergy of CNT-GNR/CuCr.

Bi-functional epoxy coating with long-term protection for Q235 steel prepared by incorporating melamine-grafted and carbon-black-modified graphene oxide

In recent years carbon materials, such as graphene oxide (GO) and carbon nanotube, have been became key materials for high-performance coatings for the protection of metals from corrosion. Here, a novel bi-functional epoxy coating was developed and formulated, which can replace traditional primers and topcoats. Furthermore, the effects of modified graphene oxide‑carbon black (MGC) on the corrosion resistance and weathering resistance of coated Q235 samples have been investigated using salt spray testing, UV accelerated aging testing, and electrochemical impedance spectroscopy. Results suggest that the incorporation of MGC leads to a considerable enhancement in the corrosion resistance and weathering resistance of coated samples. Notably, the bi-functional epoxy coating formulated with 0.2 wt% of MGC demonstrated the most effective anti-corrosion and weathering resistant properties. During the UV accelerated aging testing for 20 days, the low-frequency impedance modulus values of bi-functional epoxy coated samples were recorded to be 1.09 × 108 Ω·cm2, which is higher than pure epoxy coated samples (9.05 × 106 Ω·cm2). Also, the highest adhesion strength of bi-functional epoxy coated samples decreased from 2.51 MPa to 1.97 MPa. These observations suggest that the bi-functional epoxy maintained a significant portion of its adhesion strength even after undergoing UV accelerated aging, indicating its robustness and durability under such corrosion conditions.

Improving the emission properties of graphene–carbon nanotube hybrid nanostructures through functionalization with BaO nanoparticles and laser treatment

This paper presents the manufacturing technology of hybrid nanostructures based on a buffer layer of reduced graphene oxide (rGO) flakes with vertical single-walled carbon nanotubes (SWCNTs) and their bundles functionalized with BaO nanoparticles. Using density functional theory (DFT) calculations, supercells of rGO/SWCNT/BaO films were constructed and the patterns of the electron work function were revealed. It has been demonstrated that the electron work function is influenced by both the mass fraction of BaO nanoparticles and the inter-tube distance. Branched carbon nanostructure was formed using a pulsed laser irradiation. Fragmentation of BaO nanoparticles on the carbon surface was achieved. It was shown that after laser treatment, Ba(NO3)2 particles up to 200 nm in size were fragmented into smaller BaO nanoparticles with sizes of a few nanometers, covering the nanotubes. The field emission current–voltage characteristics (CVCs) were measured and showed a 42-fold increase in emission current compared to the nanostructure without BaO functionalization and laser treatment. BaO-functionalized hybrid carbon nanostructures are predicted to be efficient field cathodes, with a current density of at least 2 A/cm2, for use in X-ray tubes, field emission displays, and vacuum microwave devices.

Wide temperature range, air stable, transparent, and self-powered photodetectors enabled by a hybrid film of graphene and single-walled carbon nanotubes

Wide temperature range, air stable, transparent, and self-powered photodetectors enabled by a hybrid film of graphene and single-walled carbon nanotubes

Al3+ diffusion-directed assembly of GO-CNTs multi-layered composite coatings: Preparation and tribological performance

To resolve graphene coating's typical problems in tribological applications, including poor interfacial bonding, agglomeration, and low wear resistance, a dimensionally composited coating based on graphene oxide (GO) and carbon nanotubes (CNTs) was successfully prepared by a feasible metal-ion diffusion-directed assembly method. Experiments showed that the Al3+ diffusion-directed assembly method could significantly increase the coating interfacial binding strength, elasticity modulus, and hardness. In addition, the synergistic lubrication of GO and CNTs during friction enabled the Al3+-GO-CNTs5.0 coating to sustain a longer operation duration of 12,900 cycles. This study refers to inducing coordination with metal ions in various valence states and compositing carbon-based nanomaterials in different dimensions, which provides a feasible way to improve the lubricating coating's mechanical and tribological performances.