Synergistic Effect Of Graphene Oxide Research Articles

Synergistic Effect of Graphene Oxide and Different Valence of Cations on Promoting Catalase Crystallization

This study tests the effect of using the combination of graphene oxide (GO) with different valence cations as a heterogeneous nucleant on promoting catalase crystallization. By using GO and three t...

Synergistic effect of graphene oxide and sodium carboxymethylcellulose on the properties of poly(vinyl alcohol) hydrogels

ABSTRACTHydrogels are a promising candidate for applications in biomedicine and bioengineering, but their mechanical properties often restrict their applications. To improve the mechanical performance of poly(vinyl alcohol) (PVA) hydrogels, we introduced sodium carboxymethylcellulose (CMC), and graphene oxide (GO) into them. We prepared a series of composite hydrogels composed of PVA, CMC, and GO with epichlorohydrin as a chemical crosslinker. We used Fourier transform infrared spectroscopy and X‐ray diffraction to characterize the chemical structures of GO and the hydrogel. The dynamic mechanical analysis results show the synergistic enhancement effects of CMC and GO on the PVA hydrogel. The swelling process of the hydrogels also fit well with the second‐order kinetic equation. Scanning electron microscopy results suggest that the neat mesh structure facilitated superior mechanical properties in the hydrogels. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47644.

Facile Preparation of Graphene Oxide-MIL-101(Fe) Composite for the Efficient Capture of Uranium

Graphene oxide (GO)-MIL-101(Fe) (Fe-based metal-organic frameworks (MOFs) with Fe(III) as the metal anode and 2-aminobenzene-1,4-dicarboxylic acid as a ligand) sandwich composites are designed and fabricated through a facile in situ growth method. By modulating the addition amount of GO nanosheets, composites containing MIL-101(Fe) octahedrons with a tunable dimension and density are achieved. The optimized ratio between individual components is determined through adsorption experiments. Adsorption isotherms reveal an enhanced adsorption efficiency and improved adsorption capacity of GO15-MIL-101(Fe) (GO dosage is 15 mg) in comparison with raw MIL-101(Fe) nanocrystals. Experimental evidence indicates that the removal of U(VI) by the composite is based on inner-sphere surface complexation and electrostatic interaction. The improved adsorption performance originates from the optimized synergistic effects of GO and MIL-101(Fe) octahedrons. In summary, this work offers a facile synthetic method to achieve cost-effective composites towards the U(VI) capture. It also lays the foundation for the design of novel adsorbents with the full play of component’s functionality.

The Significance of Graphene Oxide-Polyacrylamide Interactions on the Stability and Microstructure of Oil-in-Water Emulsions.

The emulsification of oil in water by nanoparticles can be facilitated by the addition of costabilizers, such as polymers and surfactants. The enhanced properties of the resulting emulsions are usually attributed to nanoparticle/costabilizer synergy; however, the mechanism of this synergistic effect and its impacts on emulsion stability and microstructure remain unclear. Here, we study the synergistic interaction of graphene oxide (GO) and a high molecular weight anionic polyacrylamide (PAM) in stabilization of paraffin oil/water emulsion systems. We show that the addition of PAM reduces the amount of GO required to stabilize an emulsion significantly. In order to probe the synergistic effect of GO and PAM, we analytically analyze the oil-free GO and GO-PAM dispersions and directly image their morphology via Cryo-TEM and atomic force microscopy (AFM). X-ray diffraction results confirm the adsorption of PAM molecules onto GO sheets resulting in the formation of ultimate GO-PAM complexes. The adsorption phenomenon is a consequence of hydrogen bonding and acid-base interactions, conceivably leading to a resilient electron-donor-acceptor complex. The microstructure of emulsions is captured with two-color fluorescent microscopy and Cryo-TEM. The acquired images display the localization of GO-PAM complexes at the interface while large amount of GO-PAM flocs coexist at the interface and in between oil droplets. Localization of such complexes and flocs at the interface is found to be responsible for their slow creaming rates compared to their GO counterparts. Mechanical properties of both dispersions and emulsions are studied by shear rheology. Rheological measurements confirm that GO-PAM complexes have a higher desorption energy from the interface resulting in higher critical shear strain of GO-PAM emulsions. The results, with insights into both structure and rheology, form a foundational understanding for integration of other polymers and nanoparticles in emulsion systems, which enables efficient design of these systems for an application of interest.

Preparation and tribological properties of graphene oxide doped alumina composite coatings

In this paper, nickel matrix composite coatings incorporated with graphene oxide (GO) and graphene oxide doped alumina (GO-Al2O3) particles were fabricated through electro-deposition. Given the excellent mechanical properties of GO and Al2O3, excellent anti-wear properties are expected when embedding GO-Al2O3 particles in Ni matrix. For this purpose, nano-Al2O3 particles were first grafted on GO surfaces to fabricate the GO-Al2O3 particles. The structure, composition and morphology of the GO and GO-Al2O3 were characterized by XRD, FT-IR, SEM, TEM and BSE, respectively. The results revealed that nano-Al2O3 particles were successfully doped on GO surfaces. The tribological performances of the coatings were studied under dry sliding condition. It was found that the wear rate of Ni/GO composite coating declined by 20.9% compared to pure Ni coating. The results also indicated that the Ni/GO-Al2O3 coatings with higher amount of Al2O3 content presented the lower friction coefficients and better anti-wear behaviors. The superior tribological properties of the Ni/GO-Al2O3 coating were attributed to the synergistic effects of GO and Al2O3.

The synergistic effect of graphene oxide and silver vacancy in Ag3PO4-based photocatalysts for rhodamine B degradation under visible light

Spherical-like Ag3PO4 and graphene oxide (GO) wrapped Ag3PO4 (Ag3PO4@GO) composites with different GO contents were successfully synthesized via facile co-precipitation and ultrasonic processes. The morphologies, structures, and surface bonds of the samples were characterized by SEM, TEM, XRD, FTIR, and XPS spectroscopy. Furthermore, photocatalytic activities toward rhodamine B (RhB) degradation of these samples under visible light were evaluated. The experimental results indicated that the breaking of the weak AgO bond led to silver vacancies (VAg) in Ag3PO4 lattice, which acted as trapping centers of photo-generated holes. The enhanced photocatalytic performance of the Ag3PO4@GO samples could be explained by the synergistic effect of VAg and GO. Ag3PO4 hybrid with 10 mg GO (Ag3PO4@10GO) was turned out to have the highest content of VAg, thus leading to the optimum improvement of photocatalytic activity.

The synergistic catalytic effect between graphene oxide and three-dimensional ordered mesoporous Co3O4 nanoparticles for low-temperature CO oxidation

Three-dimensional ordered mesoporous (3D) Co3O4 as a transition metal oxide is widely used in CO catalytic oxidation, and graphene oxide has the abundant oxygen-containing groups and oxygen vacancies which are beneficial to promote the activity of Co3O4-based catalyst. In this paper, the 3D Co3O4/GO catalysts are applied to CO catalytic oxidation reaction and we studied in detail the synergistic effect between 3D Co3O4 and GO. Three dimensionally ordered mesoporous Co3O4/GO (3D Co3O4/GO) catalysts are prepared by solvothermal method. The addition of graphene oxide obviously increased the specific surface area and promoted the dispersion of active metal. The oxygen-containing groups on the surface of graphene oxide increase the reactive sites simultaneously. The synergistic effect of graphene oxide and Co3O4 made the 3D Co3O4/GO catalyst showed excellent catalytic activity. Moreover, the influence of solvent (water, ethanol, ethylene glycol) was studied. The results showed that the change of the solvent did not affect the structure of the metal oxide, but affected the chemical state of the metal and the concentration of oxygen-containing functional groups on the surface of catalyst.

Synergistic Effect of Graphene Oxide and Mesoporous Structure on Flame Retardancy of Nature Rubber/IFR Composites.

Aiming to improve the flame retardancy performance of natural rubber (NR), we developed a novel flame retardant synergistic agent through grafting of MCM-41 to graphene oxide (GO), named as GO-NH-MCM-41, as an assistant to intumescent flame retardants (IFR). The flame retardancy of NR/IFR/GO-NH-MCM-41 composites was evaluated by limited oxygen index (LOI), UL-94, and cone calorimeter test. The LOI value of NR/IFR/GO-NH-MCM-41 reached 26.3%; the UL-94 ratings improved to a V-0 rating. Moreover, the addition of GO-NH-MCM-41 decreased the peak heat release rate (PHRR) and the total heat release (THR) of the natural rubber composites. Furthermore, the addition of GO-NH-MCM-41 increased the thickness of char residue. The images of SEM indicated the char residue was more compact and continuous. The degradation of GO-NH-MCM-41-based NR composites was completed with a mass loss of 35.57% at 600 °C. The tensile strength and the elongation at break of the NR/IFR/GO-NH-MCM-41 composites were 13.9 MPa and 496.7%, respectively. The results of the rubber process analyzer (RPA) reached the maximum value, probably due to a better network of fillers in the matrix.

BIAN Based Electroactive Polymer with Defined Active Centers as Metal-Free Electrocatalysts for Oxygen Reduction Reaction (ORR) in Aqueous and Nonaqueous Media

We report design, synthesis, and performance evaluation of functional polymer material with defined active sites for oxygen reduction reaction (ORR) catalytic activity in aqueous as well as nonaqueous media. The BIAN-paraphenylene (BP) copolymer having an imine backbone was synthesized via solution based polycondensation. The as synthesized polymer itself showed ORR activity comparable to that of other doped carbon materials. The composites of the polymer with graphene oxide (GO) sheets (GO/BP) were also synthesized under moderate temperature conditions (400 °C) with the polymer remaining intact. The composites showed further enhanced electrochemical activity owing to the synergistic effect of GO and active site defined polymer material. We also tried to evaluate the nature and basis of catalytic activity on the polymer surface by different techniques. The cyclic voltammograms showed two distinct ORR peaks, indicating two different active sites. This was also in agreement with Mulliken charge distribution...

Flexible supercapacitor with high energy density prepared by GO-induced porous coral-like polypyrrole (PPy)/PET non-woven fabrics

Graphene oxide (GO)-induced porous coral-like polypyrrole have been fabricated via facile in situ polymerization. The morphologies and structures of PPy with different GO concentration were investigated by scanning electron microscopy and Fourier transform infrared spectroscopy. The results revealed that PPy/GO presented different morphologies and properties with varied amounts of GO. The electrochemical performances of prepared PPy/GO and PPy electrodes were compared. Notably, the PPy/GO electrodes showed much better electrochemical performance than the PPy electrodes. It indicated that the doping of GO in the composites significantly enhanced the electrochemical behaviors of PPy/GO electrodes. The excellent performance was the result of synergistic effects of GO and PPy structure and property. The device obtained a large specific capacitance of 568.35 F g−1 at a current density of 0.1 A/g and high energy density of 37.4 Wh kg−1. In addition, it also exhibited good cycle stability, with a capacitance retention rate of 83.4% for 500 cycles. More importantly, the electrode presented high flexibility property. The supercapacitor device fabricated is promising for the use in lightweight and flexible electronic devices.

Synergistic Effect of Graphene Oxide for Impeding the Dendritic Plating of Li

AbstractDendritic growth of lithium (Li) has severely impeded the practical application of Li‐metal batteries. Herein, a 3D conformal graphene oxide nanosheet (GOn) coating, confined into the woven structure of a glass fiber separator, is reported, which permits facile transport of Li‐ions thought its structure, meanwhile regulating the Li deposition. Electrochemical measurements illustrate a remarkably enhanced cycle life and stability of the Li‐metal anode, which is explained by various microscopy and modeling results. Utilizing scanning electron microscopy, focused ion beam, and optical imaging, the formation of an uniform Li film on the electrode surface in the case of GO‐modified samples is revealed. Ab initio molecular dynamics (AIMD) simulations suggest that Li‐ions initially get adsorbed to the lithiophilic GOn and then diffuse through defect sites. This delayed Li transfer eliminates the “tip effect” leading to a more homogeneous Li nucleation. Meanwhile, CC bonds rupture observed in the GO during AIMD simulations creates more pathways for faster Li‐ions transport. In addition, phase‐field modeling demonstrates that mechanically rigid GOn coating with proper defect size (smaller than 25 nm) can physically block the anisotropic growth of Li. This new understanding is a significant step toward the employment of 2D materials for regulating the Li deposition.

Static and Dynamic Mechanical Properties of Graphene Oxide-Incorporated Woven Carbon Fiber/Epoxy Composite

This study investigates the synergistic effects of graphene oxide (GO) on the woven carbon fiber (CF)-reinforced epoxy composites. The GO nanofiller was incorporated into the epoxy resin with variations in the content, and the CF/epoxy composites were manufactured using a vacuum-assisted resin transfer molding process and then cured at 70 and 120 °C. An analysis of the mechanical properties of the GO (0.2 wt.%)/CF/epoxy composites showed an improvement in the tensile strength, Young’s modulus, toughness, flexural strength and flexural modulus by ~ 34, 20, 83, 55 and 31%, respectively, when compared to the CF/epoxy composite. The dynamic mechanical analysis of the composites exhibited an enhancement of ~ 56, 114 and 22% in the storage modulus, loss modulus and damping capacity (tanδ), respectively, at its glass transition temperature. The fiber–matrix interaction was studied using a Cole–Cole plot analysis.

Synergistic Effect of Graphene Oxide Coated Nanotised Apigenin with Paclitaxel (GO-NA/PTX): A ROS Dependent Mitochondrial Mediated Apoptosis in Ovarian Cancer.

Ovarian cancer is most lethal among all gynecologic malignancies. Paclitaxel (PTX) is well used chemotherapeutic regimen for cancer control; however its undesired toxicity has been a matter of concern for clinicians. Here, we used the graphene oxide coated nanotised apigenin (GO-NA) to enhance the efficacy of paclitaxel. The combined use of paclitaxel (PTX) and nanotised apigenin (NA) may reduce the PTX dose and increase the efficacy. GO and GO-Apigenin was prepared by modified Hummers method and the nanoparticles were characterized by dynamic light scattering and transmission electron microscopy. SKOV-3 cells were treated by DMSO, Group I (Control)-McCoy's 5A Medium, Group II-Paclitaxel (5nM), Group III- Nanotised Apigenin (GO-NA-10µM), Group IV- Paclitaxel (5nM) + GO-NA (10µM). Cell viability and IC-50 value were determined by MTT assay, synergism by Compusyn software, ROS by DCFH-DA assay, SOD activity by kit and MMP were examined by JC-1 and mitotracker/DAPI staining, cell cycle by flow cytometry, mRNA and protein level by Real Time-PCR and Western blot respectively Results: Results showed that GO-NA-PTX enhanced the anti-proliferative effect in synergistic manner as compare to GO-NA and PTX alone. GO-NA-PTX significantly suppressed the SOD activity, promotes the ROS accumulation, mitochondrial depolarization, DNA integrity and cell cycle arrest collectively accord the apoptosis. Results of immunocytochemistry, RT-PCR and western blot showed up-regulation of caspase-3, Bax, and down-regulation of Bcl-2. The combination of PTX with GO-NA produces synergistic effects in SKOV-3 cells via the modulation of pro and anti-apoptotic gene and may reduce side effects of PTX.

Unique synergistic effects of graphene oxide and carbon nanotube hybrids on the tribological properties of polyimide nanocomposites

Abstract The graphene oxide (GO) nanosheets/carboxyl-functionalized multi-walled carbon nanotubes (CNTs) hybrids (GO/CNTs) were synthesized via vacuum filtration solution hybrid dispersion and the corresponding GO/CNTs/polyimide (GO/CNTs/PI) nanocomposite films were facilely prepared by in situ polymerization. Both the thermal stability, mechanical and tribological properties of GO/CNTs/PI nanocomposites were greatly improved compared with those of pure PI due to the homogeneous dispersion of GO/CNTs and the strong interfacial covalent bonds between GO/CNTs and the PI matrix. Furthermore, GO/CNTs/PI nanocomposites exhibited the much lower friction coefficient compared to that of PI composites with the same loading of GO or CNTs only, suggesting the synergistic effects of GO/CNTs hybrids on the tribological properties of polyimide nanocomposites, especially the weight ratio of GO and CNTs was 3:1.

Synergistic effect of graphene oxide on the methanol oxidation for fuel cell application

Aromatic polypyrene was synthesized by the oxidative polymerization of pyrene with potassium tetrachloropalladate (II), as oxidant. During the polymerization process the palladium salt was reduced to metallic palladium and forms the metal-polymer composite material. Polypyrene stabilized palladium nanoparticles showed electrocatalytic activity toward the oxidation of methanol. The performance of the electrocatalytic activity was substantially improved with the incorporation of graphene oxide to the palladium–polypyrene composite and the synergistic performance was attributed to the electronic and structural properties of the system.

Enhanced Separation Performance for CO2 Gas of Mixed-Matrix Membranes Incorporated with TiO2/Graphene Oxide: Synergistic Effect of Graphene Oxide and Small TiO2 Particles on Gas Permeability of Membranes

This study combines the adsorption layer nanoreactor synthesis (ALRS) method with in situ polymerization to prepare high-performance separation hybrid membranes containing TiO2-graphene oxide (TiO2-GO). TiO2 nanoparticles were initially generated on the GO surface through ALRS. Hybrid membranes containing A-TiO2-GO were then prepared using in situ polymerization. The inhibition of aggregation by the strong combination between the small TiO2 particles and the GO surface led to a homogeneous distribution of TiO2-GO in the polymeric matrix. This, in turn, caused a significant improvement of the membranes performance for CO2 separation. Both the small TiO2 particles and GO played an important role in increasing the gas separation performance of membranes. In particular, TiO2 small particles, with a polar surface, promoted the CO2 diffusion through the membranes, while GO addition significantly increased the solubility selectivity of the membranes toward CO2.

Preparation and characteristics of graphene oxide-blending PVDF nanohybrid membranes and their applications for hazardous dye adsorption and rejection

Graphene oxide (GO) and lithium chloride (LiCl) were introduced into poly (vinylidene fluoride) (PVDF) membranes prepared using the immersion precipitation technique. The hydrophilicity, water flux, X-ray diffraction (XRD), zeta potential, SEM and AFM images of membranes were investigated. By adjusting the content of GO from 0wt% to 0.9 wt%, the water flux of PVDF/GO/LiCl nanohybrid membranes varied from 48.4L/m2h to 61.90L/m2h at 100kPa. Because of the synergistic effects of GO and LiCl particles, the surface free energy (|ΔGs|) of M3 (0.5wt% GO) membrane was highest (103.50mJ/m2), indicating that the hydrophilicity of M3 membrane was highest. Rhodamine B aqueous solution was firstly used to determine the adsorption and desorption ability of membranes. After 20 cycles, the decolorization rates and flux recovery ratios of nanohybrid membranes exceeded 80% and 78.2% respectively, and the Rhodamine B rejection of M3 membrane was maximum (67.8%) at 100kPa, which illustrated that nanohybrid membranes can be reused as a better ultrafiltration and dye recovery material, and the characteristic of M3 membrane was best.

Synergistic effect of graphene oxide and carbon nanotubes on sulfonated poly(arylene ether nitrile)-based proton conducting membranes

A strategy to prepare graphene oxide (GO)/carbon nano-tubes (CNTs)/sulfonated poly(arylene ether nitrile) (SPEN) composite membranes aimed for the proton exchange membrane is presented herein. GO and CNTs were incorporated into SPEN to improve the performances of proton exchange membrane. To study the synergistic effect of GO and CNTs, GO/SPEN and CNTs/SPEN membranes were also fabricated. The influences of GO and CNTs upon the microstructures, including thermal and mechanical properties, water uptake, swelling, proton conductivity and methanol permeability of composite membranes were investigated in detail. The membranes combining GO and CNTs could effectively avoid the self-agglomeration of GO or CNTs. In such a way, efficient proton transport channels were constructed by homogeneous dispersion of GO and CNTs within SPEN, leading to enhancement of proton conductivity. The proton conductivity of GO/CNTs/SPEN composite membrane with the ratio of 2:2 achieved the highest value of 0.1197 S/cm at 20 °C. Meanwhile, low methanol permeability (2.015 × 10−7 cm2 s−1) was still maintained. Consequently, the combination of CNTs and GO exhibited a favorable synergistic effect on the selectivity of proton exchange membrane, which is better than pure SPEN, Nafion 117, GO/SPEN, and CNTs/SPEN membranes. This feasibility study could provide an alternative approach to design GO/CNTs-based proton-conducting membranes for DMFC applications.

Novel low temperature (<37 °C) chitosan hydrogel fabrication under the synergistic effect of graphene oxide

A low temperature chitosan hydrogel was fabricated under the synergistic effect of graphene oxide, and may be applied in hydrogel medical coatings.

Flame retardancy and ultraviolet resistance of silk fabric coated by graphene oxide

Silk fabrics were coated by graphene oxide hydrosol in order to improve its flame retardancy and ultraviolet resistance. In addition, montmorillonoid was doped into the graphene oxide hydrosol to further improve the flame retardancy of silk fabrics. The flame retardancy and ultraviolet resistance were mainly characterized by limiting oxygen index, vertical flame test, smoke density test, and ultraviolet protection factor. The synergistic effect of graphene oxide and montmorillonoid on the thermal stabilization property of the treated silk fabrics was also investigated. The results show that the treated silk fabrics have excellent flame retardancy, thermal stability, smoke suppression, and ultraviolet resistance simultaneously.