Effect Of Graphene Oxide Nanosheets Research Articles

Investigation of the mechanical characteristics and thermal behavior of a polymer matrix by addition of different graphene oxide nanosheets: A molecular dynamics simulation

Molecular dynamics simulation (MDS) was applied to examine the effect of graphene oxide nanosheets (GONs) with different edges (armchair and zig-zag edges) on the mechanical behavior (MB) and thermal behavior (TB) of the base polymer matrix (PM). The physical quantities, such as the maximum stress on the samples, stress–strain diagram, ultimate strength (US), Young's modulus (YM), the order parameter (OP), and length changes (LC) were measured for 10 ns. Lennard-Jones (LJ), Tersoff, and Coulomb potentials were used. The PM's maximum stress, US, and YM values were 0.26, 0.22, and 2.23 GPa, respectively. After 10 ns, the OP of PM decreased from 0.79 to 0.52. In studying the PM, the LC was 17 Å when increasing structure temperature to 350 K. The TB and MB of zig-zag nanosheet were higher than for the armchair type. By adding GONs with an atomic ratio of 1% to PM, maximum stress, US, and YM values in structures with armchair nanosheets were 0.34, 0.28, and 2.78 GPa, respectively, and for samples with zig-zag nanosheets were 0.35, 0.30, and 2.96 GPa. After 10 ns, LC increased from 10 to 11 Å for the sample with a zig-zag edge, and from 10 to 12 Å for an armchair edge. This atomic behavior indicated that the atomic structure of Detda and Dgeba matrixes with GONs with a zig-zag edge had higher thermal stability.

Effect of graphene oxide on microstructure and micromechanical property of ultra-high performance concrete

This paper aims to investigate the effects of graphene oxide (GO) on the microstructure and micromechanical properties of ultra-high performance concrete (UHPC) matrix and interfacial transition zone (ITZ) around the embedded steel fiber, and to reveal the working mechanism of GO, so as to fully understand the mesoscopic and macroscopic mechanical behaviors of GO reinforced UHPC. Mercury intrusion porosimetry (MIP) and backscattered electron microscopy (BSEM) were used to systematically study the microstructure evolution, and nanoindentation test was used to quantitatively characterize the microscale fracture toughness of UHPC matrix and ITZ. The results showed that GO induced more calcium-silicate-hydrate generation, which significantly reduced the porosity of the ITZ between steel fiber and matrix from 7.5-13.4% to 5.3%–10.5%, and promoted the homogenization of the microstructure. Due to the decrease of porosity and the bridge effect of GO nanosheets, the microscale fracture toughness in ITZ increases by 24.9% from 0.994 MPa m1/2 to 1.241 MPa m1/2 at the critical dosage of 0.04% GO, which is conducive to the improvement of the interface bonding between steel fibers and matrix, and thus increasing the macroscopic flexural strength of straight steel fiber UHPC and hooked-end fiber UHPC by 14.7% and 13.9% respectively.

Effect of GO nanosheets on microstructure, mechanical and fracture properties of cement composites

The aim of the present paper is to investigate the effects of graphene oxide (GO) nanosheets addition in a cement-based material from both a microstructural and a mechanical/fracture point of view. In particular, an experimental campaign is performed on both plain mortar and mortar reinforced with 0.03% GO nanosheets, obtained through the Brodie’s method. The chemical and microstructural characterisation of the above materials is carried out by employing X-ray powder diffraction and SEM-EDS analyses, whereas the mechanical properties and fracture toughness are determined through flexural, compressive and fracture tests.

Synergistic Lubricating Performance of Graphene Oxide and Modified Biodiesel Soot as Water Additives

The tribological performance of graphene oxide (GO) nanosheets, modified biodiesel soot (MBS) nanoparticles, and their mixture (MBS–GO) nanoparticles as lubricant additives in water was evaluated using a reciprocating ball-on-plate tribometer. The effects of different mass ratios of GO to MBS, additive concentrations, and loads, as well as corresponding lubrication mechanisms, were studied. The tribological measurements showed that the water-containing 0.5 wt% additives at a mass ratio of 60:40 (GO to MBS) resulted in larger reductions in friction coefficient (69.7%) and wear volume (60.5%) than water. Owing to the synergistic effect of GO nanosheets and MBS nanoparticles, the MBS–GO aqueous sample showed superior lubricating properties compared to water as well as GO and MBS aqueous samples. The good tribological properties of MBS–GO nanoparticles in water are attributed to the formation of a tribofilm of hybrid nanoparticles that effectively protects the friction interface. Moreover, the MBS nanoparticles can provide lubrication by acting as ball bearings.

Friction and Wear Characteristics of Aqueous ZrO2/GO Hybrid Nanolubricants

Aqueous nanolubricants containing ZrO2 nanoparticles, graphene oxide (GO) nanosheets, or hybrid nanoparticles of ZrO2 and GO were formulated using a cost-effective ultrasonication de-agglomeration method. The friction and wear characteristics of these water-based nanolubricants were systematically investigated using a block-on-ring testing configuration with a stainless- and alloy steel contact pair. The concentrations and mass ratios of nanoadditives were varied from 0.02 to 0.10 wt.% and 1:5 to 5:1, respectively, to obtain optimal lubrication performance. The application of a 0.06 wt.% 1:1 ZrO2/GO hybrid nanolubricant resulted in a 57% reduction in COF and a 77% decrease in wear volume compared to water. The optimised ZrO2/GO hybrid nanolubricant was found to perform better than pure ZrO2 and GO nanolubricant in terms of tribological performance due to its synergistic lubrication effect, which showed up to 54% and 41% reductions in friction as well as 42% and 20% decreases in wear compared with 0.06 wt.% ZrO2 and 0.06 wt.% GO nanolubricants. The analysis of wear scars revealed that using such a ZrO2/GO hybrid nanolubricant yielded a smooth worn surface, with 87%, 45%, and 33% reductions in Sa compared to water and 0.06 wt.% ZrO2 and 0.06 wt.% GO nanolubricants. The superior tribological performance can be ascribed to the combination of the rolling effect of ZrO2 nanoparticles and the slipping effect of GO nanosheets.

Antifoaming effect of graphene oxide nanosheets in polymer-modified cement composites for enhanced microstructure and mechanical performance

Polymer modified cement (PMC) composites attract attention due to their outstanding durability. However, reduced compressive strength caused by the air-entrainment restricts their application. Herein, a novel approach derived from 2D graphene oxide (GO) nanosheets to mitigate air-entrainment and enhance the mechanical performance of PMC is presented. The GO nanosheets tailor the polymer interaction with the cement matrix and act as an antifoaming agent in the GO-polymer modified composite (GOPMC). Microscopy and dispersion results demonstrated that GO nanosheets transform agglomerated polymer particles into a well-dispersed assembly and prevent their air-entraining effect. Chemical structure alteration of the air-entrained polymer by GO and promoted hydration was observed. Accordingly, the developed GOPMC without any conventional defoamer exhibited a 60.1% lower pore volume and improved 28-day tensile and compressive strengths by 59% and 33%, respectively, compared with PMC. The unveiled defoaming effect of the GO nanosheets introduces a new mechanism to fabricate hybrid cement composites.

Assessing the properties of thin-film nanocomposite membrane embedded with GO nanosheets using the DSPM-DE model

In this work, the effect of embedding graphene oxide (GO) nanosheets into the polyamide (PA) layer of thin-film nanocomposite (TFN) membrane properties, including the pore radius (rp), pore dielectric constant (εp), and charge density (Xd), was studied by applying Donnan-steric-pore-model-dielectric-exclusion (DSPM-DE) model. A TFN membrane was fabricated via interfacial polymerization by dispersing GO in an aqueous m-phenylenediamine solution. Characterizations using atomic force microscopy, zeta potential and contact angle of fabricated TFN membrane showed a smooth surface, a high negative surface charge and hydrophilic nature. X-ray photoelectron spectroscopy and Fourier transform infrared analyses confirmed the incorporation of GO in the PA layer of the TFN membrane. The Supply–Demand-Based Optimisation (SDO) algorithm was applied as an appropriate technique to fit experimental values of NaCl rejection with the DSPM-DE model to predict membrane properties. The SDO algorithm showed an excellent agreement between experimental data and the DSPM-DE model and the ability to predict accurate values of TFN membrane characteristics. The obtained results indicate no significant effect of GO nanosheets on the pore radius of the PA layer. The Xd of membranes increased toward negative with NaCl concentration due to adsorbing chloride ions onto the membrane surfaces. The Xd increase in TFN membrane was more because of GO presence; thereby TFN membrane performance improved. The εp value of the solution inside pores for the TFC membrane decreased more than the TFN membrane.

Lethal Interactions of SARS-CoV-2 with Graphene Oxide: Implications for COVID-19 Treatment.

The rapid transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-driven infection signifies an ultimate challenge to global health, and the development of effective strategies for preventing and/or mitigating its effects are of the utmost importance. In the current study, an in-depth investigation for the understanding of the SARS-CoV-2 inactivation route using graphene oxide (GO) is presented. We focus on the antiviral effect of GO nanosheets on three SARS-CoV-2 strains: Wuhan, B.1.1.7 (U.K. variant), and P.1 (Brazilian variant). Plaque assay and real-time reverse transcription-polymerase chain reaction (RT-PCR) showed that 50 and 98% of the virus in a supernatant could be cleared following incubation with GO (100 μg/mL) for 1 and 60 min, respectively. Transmission electron microscopy (TEM) analysis and protein (spike (S) and nucleocapsid (N) proteins) decomposition evaluation confirm a two-step virus inactivation mechanism that includes (i) adsorption of the positively charged spike of SARS-CoV-2 on the negatively charged GO surface and (ii) neutralization/inactivation of the SARS-CoV-2 on the surface of GO through decomposition of the viral protein. As the interaction of S protein with human angiotensin-converting enzyme 2 (ACE2) is required for SARS-CoV-2 to enter into human cells, the damage to the S protein using GO makes it a potential candidate for use in contributing to the inhibition of the worldwide spread of SARS-CoV-2. Specifically, our findings provide the potential for the construction of an effective anti-SARS-CoV-2 face mask using a GO nanosheet, which could contribute greatly to preventing the spread of the virus. In addition, as the effect of surface contamination can be severe in the spreading of SARS-CoV-2, the development of efficient anti-SARS-CoV-2 protective surfaces/coatings based on GO nanosheets could play a significant role in controlling the spread of the virus through the utilization of GO-based nonwoven cloths, filters, and so on.

Microfluidic investigation of the effect of graphene oxide on mechanical properties of cell and actin cytoskeleton networks: experimental and theoretical approaches

Biomechanical and morphological analysis of the cells is a novel approach for monitoring the environmental features, drugs, and toxic compounds’ effects on cells. Graphene oxide (GO) has a broad range of medical applications such as tissue engineering and drug delivery. However, the effects of GO nanosheets on biological systems have not been completely understood. In this study, we focused on the biophysical characteristics of cells and their changes resulting from the effect of GO nanosheets. The biophysical properties of the cell population were characterized as follows: cell stiffness was calculated by atomic force microscopy, cell motility and invasive properties were characterized in the microfluidic chip in which the cells are able to visualize cell migration at a single-cell level. Intracellular actin was stained to establish a quantitative picture of the intracellular cytoskeleton. In addition, to understand the molecular interaction of GO nanosheets and actin filaments, coarse-grained (CG) molecular dynamics (MD) simulations were carried out. Our results showed that GO nanosheets can reduce cell stiffness in MCF7 cells and MDA-MB-231 cell lines and highly inhibited cell migration (39.2%) in MCF-7 and (38.6%) in MDA-MB-231 cell lines through the GO nanosheets-mediated disruption of the intracellular cytoskeleton. In the presence of GO nanosheets, the cell migration of both cell lines, as well as the cell stiffness, significantly decreased. Moreover, after GO nanosheets treatment, the cell actin network dramatically changed. The experimental and theoretical approaches established a quantitative picture of changes in these networks. Our results showed the reduction of the order parameter in actin filaments was 23% in the MCF7 cell line and 20.4% in the MDA-MB-231 cell line. The theoretical studies also showed that the GO nanosheet–actin filaments have stable interaction during MD simulation. Moreover, the 2D free energy plot indicated the GO nanosheet can induce conformational changes in actin filaments. Our findings showed that the GO nanosheets can increase the distance of actin-actin subunits from 3.22 to 3.5 nm and in addition disrupt native contacts between two subunits which lead to separate actin subunits from each other in actin filaments. In this study, the biomechanical characteristics were used to explain the effect of GO nanosheets on cells which presents a novel view of how GO nanosheets can affect the biological properties of cells without cell death. These findings have the potential to be applied in different biomedical applications.

Acid-Resistance Enhancement of Thin-Film Composite Membrane Using Barrier Effect of Graphene Oxide Nanosheets.

In this study, the effect of graphene oxide nanosheets (GONs) embedded in a thin-film composite (TFC) polyamide (PA) membrane on the acid resistance of the membrane was investigated by comparison with the effect of oxidized single-walled carbon nanotubes (o-SWNTs). Both GONs and o-SWNTs increased the hydrophilicity of the membranes and caused the formation of ridges and clustered bumps on the surfaces, resulting in slightly improved water permeability. However, the o-SWNTs-embedded membrane did not show a difference in acid resistance depending on the concentration of embedded material, but the acid resistance of the GONs-embedded membrane increased with increasing concentration. The acid resistance of the GONs-embedded membranes appears to be mainly due to the barrier effect caused by the nanosheet shape of the GONs along with a sacrificial role of the PA layer protruded by the addition of GONs and the decrease of acid reaction sites by the hydrogen bonding between GONs and PA. When the TFC PA membrane was prepared with a high amount (300 ppm) of the GONs without considering aggregation of GONs, membrane selectivity exceeding 95% was maintained 4.7 times longer than the control TFC membrane. This study shows that the acid resistance can be enhanced by the use of GONs, which give a barrier effect to the membrane.

Graphene Oxide Membranes for Tunable Ion Sieving in Acidic Radioactive Waste.

Graphene oxide (GO) membranes with unique nanolayer structure have demonstrated excellent separation capability based on their size‐selective effect, but there are few reports on achieving ion–ion separation, because it is difficult to inhibit the swelling effect of GO nano sheets as well as to precisely control the interlayer spacing d to a specific value between the sizes of different metal ions. Here, selective separation of uranium from acidic radioactive waste containing multication is achieved through a precise dual‐adjustment strategy on d. It is found that GO swelling is greatly restricted in highly acidic solution due to protonation effect. Then the interlayer spacing is further precisely reduced to below the diameter of uranyl ion by increasing the oxidation degree of GO. Sieving uranyl ions from other nuclide ions is successfully realized in pH =3–3 mol L−1 nitric acid solutions.

The effect of graphene oxide nanosheets (GONSs) and graphene oxide quantum dots (GOQDs) on corrosion resistance enhancement of Ni–Fe nanocomposite coatings

The effect of graphene oxide nanosheets (GONSs) and graphene oxide quantum dots (GOQDs) on corrosion resistance enhancement of Ni–Fe nanocomposite coatings

Carbon microspheres coated with graphene oxide nanosheets as oil-based additives for tribological applications

Carbon microspheres (CMS) coated with graphene oxide (GO) nanosheets particles were prepared and applied as an efficient lubricant additive for enhancing the tribological performances of lubricating oil in the boundary and mixed lubrication regimes. CMS was functionalized by 3-aminopropyltriethoxysilane (APTES) and then grafted with GO nanosheets suspension in the presence of catalysts. The tribological behaviors was studied using a tribometer under ball-on-disk (BOD) configurations. The hybrid lubricant containing 0.2-wt % graphene oxide/functionalized carbon microspheres (GO/f-CMS) particles exhibited a significant reduction in friction and wear (26 %–54 %) as compared with the reference engine oil (85W-90). Raman and SEM investigation of GO/f-CMS following the tribo-test proved their excellent mechanical and chemical stabilities. These performance improvements were attributed to the bearing and filling mechanisms of spherical particles and superior lubrication effect of GO nanosheets.

Effect of Graphene Oxide Nanosheets on Physical Properties of Ultra-High-Performance Concrete with High Volume Supplementary Cementitious Materials.

Nanomaterials have been increasingly employed for improving the mechanical properties and durability of ultra-high-performance concrete (UHPC) with high volume supplementary cementitious materials (SCMs). Recently, graphene oxide (GO) nanosheets have appeared as one of the most promising nanomaterials for enhancing the properties of cementitious composites. To date, a majority of studies have concentrated on cement pastes and mortars with fewer investigations on normal concrete, ultra-high strength concrete, and ultra-high-performance cement-based composites with a high volume of cement content. The studies of UHPC with high volume SCMs have not yet been widely investigated. This paper presents an experimental investigation into the mini slump flow and physical properties of such a UHPC containing GO nanosheets at additions from 0.00 to 0.05% by weight of cement and a water–cement ratio of 0.16. The study demonstrates that the mini slump flow gradually decreases with increasing GO nanosheet content. The results also confirm that the optimal content of GO nanosheets under standard curing and under steam curing is 0.02% and 0.04%, respectively, and the corresponding compressive and flexural strengths are significantly improved, establishing a fundamental step toward developing a cost-effective and environmentally friendly UHPC for more sustainable infrastructure.

Significantly improved high-rate partial-state-of-charge performance of lead-acid batteries induced by trace amount of graphene oxide nanosheets

• Trace amount of GONs is incorporated into the NAMs of LABs through a novel and simple way. • The NAMs containing 2 ppm GONs presents a spongy-like structure composed of porous Pb sticks. • Sulfation is suppressed due to the acceleration of the redox reaction between Pb and PbSO 4 . • The HRPSoC cycling life of the simulated cell increased by more than 1.4 times to 29,971 cycles. • The hydrogen generation almost has not any improvement because of the trace GONs content. In this work, trace amount of graphene oxide nanosheets (GONs) is incorporated into the negative active materials (NAMs) of lead-acid batteries (LABs) using an innovative and simple way. The effect of GONs on the morphologies, structures and compositions of the synthesized GONs-containing NAMs are investigated. It is observed that after formation, the NAMs containing 2 ppm GONs presents a spongy-like structure comprised of one-dimensional (1D) porous Pb sticks. Such a 1D structure of Pb sticks provides fast electron transport channel, while the pores on Pb sticks and the voids among Pb sticks facilitate electrolyte transportation. Therefore, accumulation of PbSO 4 crystals is greatly suppressed. Several electrochemical methods such as cyclic voltammetry and electrochemical impedance spectroscopy are used to understand the enhancement mechanism. It is found that the high-rate partial-state-of-charge (HRPSoC) cycling life of the simulated cell is increased by more than 1.4 times from 21,305 to 29,971 cycles. Although the electrochemical performance of NAMs is significantly improved, the hydrogen generation does not have any promotion because of the trace GONs content. The results demonstrate that our method is of great convenient and ultra-low cost with feasibility in large-scale application in LABs industry. Significantly improvement on the electrochemical performance of NAMs by incorporation of trace amount of GONs.

Effect of Graphene Oxide Nano-Sheets on Structural, Morphological and Photocatalytic Activity of BiFeO3-Based Nanostructures.

Photocatalysts are widely used for the elimination of organic contaminants from waste-water and H2 evaluation by water-splitting. Herein, the nanohybrids of lanthanum (La) and selenium (Se) co-doped bismuth ferrites with graphene oxide were synthesized. A structural analysis from X-ray diffraction confirmed the transition of phases from rhombohedral to the distorted orthorhombic. Scanning electron microscopy (SEM) revealed that the graphene nano-sheets homogenously covered La–Se co-doped bismuth ferrites nanoparticles, particularly the (Bi0.92La0.08Fe0.50Se0.50O3–graphene oxide) LBFSe50-G sample. Moreover, the band-gap nanohybrids of La–Se co-doped bismuth ferrites were estimated from diffuse reflectance spectra (DRS), which showed a variation from 1.84 to 2.09 eV, because the lowering of the band-gap can enhance photocatalytic degradation efficiency. Additionally, the photo-degradation efficiencies increased after the incorporation of graphene nano-sheets onto the La–Se co-doped bismuth ferrite. The maximum degradation efficiency of the LBFSe50-G sample was up to 80%, which may have been due to reduced band-gap and availability of enhanced surface area for incoming photons at the surface of the photocatalyst. Furthermore, photoluminescence spectra confirmed that the graphene oxide provided more electron-capturing sites, which decreased the recombination time of the photo-generated charge carriers. Thus, we can propose that the use of nanohybrids of La–Se co-doped bismuth ferrite with graphene oxide nano-sheets is a promising approach for both water-treatment and water-splitting, with better efficiencies of BiFeO3.

Dynamic increased reinforcing effect of graphene oxide on cementitious nanocomposite

The reinforcing effect of graphene oxide on cementitious materials under high strain rate remains largely unknown. Existing studies on microfiber reinforced cementitious composites showed that the dynamic increase factor (DIF) decreases due to these fibres. This study reports that the reinforcing effect of graphene oxide nanosheets can, in contrast, increase with strain rate. Tensile splitting and compression tests were conducted under both static and dynamic loadings. High strain rate, up to 1700 s−1, is achieved using a split Hopkinson pressure bar apparatus. It is found that the DIF of graphene oxide nanocomposite only increase when the DIF is higher than a threshold which is about 780 and 30 s−1 for compression and tensile test respectively. The increased of DIF was correlated with the speed of crack development and pull-out of the graphene oxide nanosheets. Also, the pull-out or fracture of graphene oxide on fragmented sand was also found a possible contributing factor to the increased DIF. The findings of this study indicate the future potential of atomic-thin nanosheets for materials under extreme impact and blast loading.

Effect of graphene oxide nanosheets on visible light-assisted antibacterial activity of vertically-aligned copper oxide nanowire arrays

In the present work, the effect of graphene oxide (GO) nanosheets on the antibacterial activity of CuO nanowire arrays under visible light irradiation is shown. A combined thermal oxidation/electrophoretic deposition technique was employed to prepare three-dimensional networks of graphene oxide nanosheets hybridized with vertically aligned CuO nanowires. With the help of standard antibacterial assays and X-ray photoelectron spectroscopy, it is shown that the light-activated antibacterial response of the hybrid material against gram-negative Escherichia coli is significantly improved as the oxide functional groups of the GO nanosheets are reduced. In order to explore the physicochemical mechanism behind this behavior, ab-initio simulations based on density functional theory were performed and the effect of surface functional groups and hybridization were elucidated. Supported by the experiments, a three-step photo-antibacterial based mechanism is suggested: (i) injection of an electron from CuO into rGO, (ii) localization of the excess electron on rGO functional groups, and (iii) release of reactive oxygen species lethal to bacteria. Activation of new photoactive and physical mechanisms in the hybrid system makes rGO-modified CuO nanowire coatings as promising nanostructure devices for antimicrobial applications in particular for dry environments.

Self-assembly of graphene oxide nanosheets in t-butanol/water medium under gamma-ray radiation

The research on the properties of graphene oxide (GO) in various media has become one of the hottest topics since GO is now the main raw material for graphene-based advanced materials. In this work, the γ-ray radiation chemistry effect of GO nanosheets and their self-aggregation behavior in t-butanol/water medium were investigated. The results show that GO nanosheets are reduced and hydroxyalkylated simultaneously by the alcohol free radicals produced by the radiolysis of t-butanol/water solution under γ-ray radiation. The radiation-modified GO nanosheets will self-assemble into a self-standing graphene hydrogel when the pH of the solution is lower than 2. A hydroxyl-functionalized free-standing graphene aerogel is further obtained simply by freeze-drying. This work provides not only a general self-assembly mechanism of GO nanosheets in strong acidic alcohol/water media under high energy radiation, but also a facile and economical preparation method for hydroxyalkylated graphene-based aerogel.

Effect of graphene oxide nanosheets and ultrasonic electrodeposition technique on Ni–Mo/graphene oxide composite coatings

Nano Ni–Mo/graphene oxide (GO) sheet composites were successfully prepared by direct current electrodeposition with ultrasonic (WS) vibration on low-carbon steel. The composite coatings’s roughness, microhardness, corrosion and oxidation resistance, which were influenced by GO and ultrasonic factors, were investigated. Results from scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) showed reduced graphene oxide (rGO) distributed in the coatings. X-ray diffraction patterns indicated that a decreased grain size of the nanocrystalline composite coatings after ultrasonic modification. In addition, results from thermogravimetric analysis from 25 °C to 600 °C showed that incorporating GO enhanced oxidation resistance. Best corrosion resistance value of 3.62 KΩ cm2 and 7.4 μA cm−2 of the ultrasonicated coatings (Ni–Mo/GO) were detected compared with coatings (Ni–Mo/GO) without sonic treatment or Ni–Mo coating.