Synergetic Effect Of Graphene Research Articles

Experimental investigation of graphene filled flax/E-glass/epoxy hybrid nanocomposites on physical, mechanical, and thermal properties

The synergetic effect of graphene as a matrix strengthener in hybrid (flax/E-glass/epoxy) fiber-reinforced polymer (HFRP) composites at various compositions was investigated. The physical, mechanical, and thermal properties of the HFRP composites were thoroughly evaluated for various wt.% of graphene added to the epoxy resin. The HFRP composites were prepared by adding graphene to epoxy resin was impregnated on the flax/E-glass fabric using the compression molding technique. Significant improvement of tensile strength, flexural strength, shear strength, shore D hardness, impact strength and interlaminar shear strength (ILSS) of the composites increased by 86%, 85%, 43%, 26%, 50%, and 80% respectively at 0.6 wt.% of graphene. Considerable reduction in the percentage of water absorption was also observed. Thermogravimetric analysis (TGA) was used to evaluate the thermal degradation of the composites, and the effect of surface treatment on flax fiber was validated using Fourier-transform infrared spectroscopy (FTIR). Fractography revealed that the main failure mechanism was due to matrix fracture and interfacial debonding. The results showed that 0.6 wt.% of graphene with HFRP composite laminates significantly improved the strength of composites and make them highly suitable for automobiles and structural applications.

Synergetic effects of graphene nanoplatelets/montmorillonite on their dispersion and mechanical properties of the epoxy‐based nanocomposite: Modeling and experiments

AbstractThe mechanical properties of nanocomposites are significantly affected by the dispersion of nanofillers. In this study, the synergetic effect of hybrid fillers, including surfacemodified montmorillonite (MMT) nanoclay and graphene nanoplatelets (GNPs) on the dispersion quality and mechanical characteristics of epoxy‐based nanocomposites was investigated. It was manifested that the incorporation of GNPs‐MMT hybrid into pure epoxy improves the dispersion of nanoplatelets and consequently, the tensile and flexural properties. The maximum tensile and flexural strength was obtained for the sample containing 0.15 wt% GNPs and 1 wt% MMT that was 19% and 17.4% higher than the neat epoxy, respectively. The experimental analyses were followed by Mori–Tanaka, Halpin–Tsai, and two‐parameter Weibull distribution methods to model the mechanical behavior of nanocomposites. The modeling and experimental results as well as the microscopic analysis revealed the variation of toughening mechanisms from micro to nano scale.

Layer-by-Layer Structure Design of G@SiOx@PPY Materials as Promising High-Performance Anodes for Lithium-Ion Batteries

The graphene/silicon oxide/polypyrrole (G/SiOx/PPY) material was prepared in this paper. The G/SiOx/PPY material has good electrochemical performances including high capacity and cyclic stability. It has 2068/2130[Formula: see text]mAh g[Formula: see text] of capacity after 100th charge/discharge cycle at 200[Formula: see text]mA[Formula: see text]g[Formula: see text] of current density and 575/569[Formula: see text]mAh[Formula: see text]g[Formula: see text] of capacity after 100th charge/discharge cycle at 2000[Formula: see text]mA g[Formula: see text] of current density when G/SiOx molar ratio is 1:5. Its capacity increases but its cyclic stability decreases with G/SiOx molar ratio decreasing from 1:1 to 1:3 and 1:5. The electrochemical performance improvement of the G/SiOx/PPY material is due to the synergetic effect of graphene and polypyrrole, which improve the conductivity of SiOx and prevent its dropping from the surface of the electrode caused by the stress due to the volume expansion and shrinkage in charge/discharge cycles.

Synergetic Effects of Graphene Nanoplatelets/Tapioca Starch on Water-Based Drilling Muds: Enhancements in Rheological and Filtration Characteristics.

Several borehole problems are encountered during drilling a well due to improper mud design. These problems are directly associated with the rheological and filtration properties of the fluid used during drilling. Thus, it is important to investigate the mud rheological and filtration characteristics of water-based drilling muds (WBMs). Several materials have been examined but due to the higher temperature conditions of wells, such materials have degraded and lost their primary functions. In this research, an attempt was made to prepare a water-based mud by utilizing graphene nano platelets (GNP) in addition to the native tapioca starch at different ratios. The combined effect of starch and graphene nano platelets has been investigated in terms of mud’s rheological and filtration parameters, including its plastic viscosity (PV), yield point (YP), fluid loss volume (FLV) and filtercake thickness (FCT). The morphological changes in the filtercake have also been observed using Field Emission Scanning Electron Microscope (FESEM) micrographs. Plastic viscosity was increased from 18–35 cP, 22–31 cP and 21–28 cP for 68 °F, 250 °F and 300 °F, respectively. The yield point was also enhanced from 22–37 lb/100ft2, 26–41 lb/100ft2 and 24–31 lb/100ft2 at the studied range. The fluid loss was dramatically reduced from 14.5–6.5 mL, 17.3–7.5 mL and 36–9.5 mL at 68 °F, 250 °F and 300 °F respectively. Similarly, filtercake thickness was also reduced which was further illustrated by filtercake morphology.

A new electrochemical sensor for simultaneous detection of sulfamethoxazole and trimethoprim antibiotics based on graphene and ZnO nanorods modified glassy carbon electrode

A novel electrochemical sensor based on graphene (GR) and ZnO nanorods (GR-ZnO/GCE) was developed to detect sulfamethoxazole (SMX) and trimethoprim (TMP) simultaneously. SEM image showed that ZnO had a rod shaped morphology. XRD result indicated a hexagonal wurtzite phase of ZnO nanorods. The electrochemical experiment results showed that the synergetic effect of GR and ZnO endowed the prepared sensor excellent electrocatalytic behavior towards the oxidation of SMX and TMP. SMX and TMP were detected by DPV method at 0.85 V and 1.06 V, respectively. Under the optimal conditions, the GR-ZnO/GCE showed superior wide linear responses in concentration range of 1–220 μmol/L for SMX and 1–180 μmol/L for TMP with the limit of detection (LOD) of 0.4 μmol/L and 0.3 μmol/L, respectively. In addition, the sensor has good stability, good selectivity, anti-jamming ability and reproducibility. We tested SMX and TMP in lake water, tap water, urine and serum with recovery between 93.2% and 108%. The proposed sensor has a good application prospect in biomedicine and environmental protection.

Synergetic effect of graphene and Co(OH)2 as cocatalysts of TiO2 nanotubes for enhanced photogenerated cathodic protection

A layer of graphene (GR) particles was successfully deposited at the interface between Co(OH)2 nanoparticles and TiO2 nanotubes, aiming to improve the photoelectrochemical performance of the large-bandgap semiconductor TiO2. The obtained Co(OH)2/GR/TiO2 was extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis absorption spectra and photoluminescence (PL) emission spectra. Electrochemical impedance spectra, photogenerated potential-time (E-t), photocurrent density-time (i-t) and i-E curves and open circuit potential (OCP) curves were measured to investigate the photoelectrochemical activities and photogenerated cathodic protection properties. The results revealed that Co(OH)2/GR/TiO2 exhibits excellent photoelectrochemical and photogenerated cathodic performance due to synergistic effect between Co(OH)2 and graphene. Co(OH)2 and graphene co-modified TiO2 photoanode could provide an effective protection for 304 stainless steel (304SS) in 3.5 wt% NaCl solution for 12 h, which would be promising for future practical applications in the field of marine corrosion protection.

Synergetic effects of graphene-CoPc/silk fibroin three-dimensional porous composites as catalysts for acid red G degradation.

The disposal of dye wastewater is one of the hotspots of scientific research. Upon combining the ability of graphene to accelerate the hydroxyl radical generation with the Fenton system, it has shown a faster degradation rate and can be recycled, showing greater degradation efficiency than the traditional dye treatment method. Herein, a catalytic system based on the regenerated silk fibroin (SF) gel integrated with cobalt tetraaminophthalocyanine (CoTAPc)-grafted-reduced graphene oxide (RGO) sheets were fabricated, and its catalytic activity was assessed via the degradation of acid red G (ARG) at varying catalyst and H2O2 dosages, pH values, and temperatures. The results revealed that the three-dimensional (3D) porous RGO-CoTAPc/SF gel exhibited a much stronger catalytic behavior than the other arbitrary components due to its high surface area and synergetic hydroxyl radical generation efficiency, with the dye removal ratio by RGO-CoTAPc/SF being higher in an acidic medium than in an alkaline medium. It also increases with the increase in temperature and RGO-CoTAPc/SF and H2O2 dosages. Further, the catalytic oxidation process of ARG was determined, and the possible degradation mechanism of ARG has been discussed. Our results suggest that the composite materials with high catalytic activity can provide a reference for future Fenton-like catalytic systems.

A review of the mechanical and thermal properties of graphene and its hybrid polymer nanocomposites for structural applications

In the present review, the recent progress in describing the intricacies of mechanical and thermal properties of all types of graphene- and modified graphene-based polymer nanocomposites has been comprehensively examined. The effectiveness of microscopy bouquet for the intrinsic characterization of graphene family and their composites was clearly demonstrated in this research. Furthermore, the utility of the dynamic mechanical analysis and thermo-gravimetric analysis employed for thermal characterization that has been reported by various researchers was exhaustively analyzed in this paper. This research primarily focused on the analyses of several good articles concerned with hybrid graphene composites and the synergetic effect of graphene with other nanofiller to assess its effect on the mechanical properties of its corresponding composites. Such systematic analysis of previous literatures imparted a direction to the researchers about the solution of improved interfacial properties as well as the enhanced dispersion into the vicinity of the matrix. This current research has suggested that the presence of the graphene filler even at very low loadings has shown considerable improvement in the overall mechanical properties of graphene. Further studies to optimize the value of the filler need to be addressed in order to gain complete understanding of the properties of graphene. The potential applications, current challenges, and future perspectives pertaining to these nanocomposites were elaborately discussed in the current study with regard to the multi-scale capabilities and promising developments of the graphene-family-based nanocomposites materials.

Li2TiO3/Graphene and Li2TiO3/CNT Composites as Anodes for High Power Li–Ion Batteries

AbstractThree‐dimensional composites Li2TiO3/graphene (LTO/Gr) and Li2TiO3/carbon nanotube (LTO/CNTs) were synthesized by solid‐state reaction for application as anode materials for lithium‐ion batteries. These composites are structurally characterized by X‐ray diffraction, Raman spectroscopy and high‐resolution transmission electron microscopy, while electrochemically tests are performed by cyclic voltammetry and chronopotentiometry. The synergetic effect of graphene and CNTs with LTO facilitate the network conduction leading to faster electron and Li+ ion transfer and improve cycling stability and rate capability of the anode. The LTO/Gr and LTO/CNTs composites exhibited an initial discharge capacity as high as 154 and 149 mAh g−1 at 1C rate, respectively and retained excellent cycling stability of 98% and 96% after 30 charge–discharge cycles.

Revisiting the conversion reaction in ultrafine SnO2 nanoparticles for exceptionally high-capacity Li-ion battery anodes: The synergetic effect of graphene and copper

Generally, in SnO2-based anode materials, the reversible alloying/dealloying reaction is the main Li-ion storage mechanism. Interestingly, these materials can show an exceptionally high capacity that is beyond the theoretical value (i.e., 783 mA h g−1 based on Sn + 4.4Li+ + 4.4e− ⇌ Li4.4Sn reaction), owing to the reversibility of the reaction between Sn and Li2O to form SnOx (x = 1, 2), so-called conversion reaction. Herein, we prepare Cu-reduced graphene oxide (rGO)-SnO2 nanocomposites as a model system in order to demonstrate an effective strategy to improve the reversibility of the conversion reaction in SnO2. The incorporation of rGO can prevent the aggregation of SnO2 nanoparticles. Furthermore, the Cu-rGO-SnO2 nanocomposite exhibits the most improved conversion reaction reversibility, resulting in improved cycling performance and high capacity. Ex-situ transmission electron microscopy analysis confirms the high reversibility of the conversion as well as the alloying/dealloying reactions. Also, Cu nanoparticles promote the decomposition of amorphous Li2O, leading to enhancement of the conversion reaction between Sn and Li2O. Therefore, these results demonstrate a strategy for significantly improving the electrochemical performances of SnO2-based anodes for Li-ion batteries.

The synergetic effect of graphene and MoS2 on AgInZnS for visible-light driven photocatalytic H2 evolution

A ternary complex of AgInZnS/MoS2-GO was successfully synthesized via a two-step hydrothermal method. Layered structured MoS2-GO plays a key role in enhancing the photocatalytic performance for hydrogen evolution. The synthesized product was further characterized by transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman et al. The nanocomposite with 1 wt % MoS2-GO in the heterojunction photocatalyst exhibits the highest rate of hydrogen evolution rate of 1302 μmol h−1. A detailed mechanism has been developed to explain the significantly enhanced catalytic activities. The nanohybrid showed enhanced photocatalytic activity towards water splitting, arising from synergetic effect of Graphene and MoS2 since MoS2 can provide active sites for hydrogen evolution while graphene can facilitate the charge transfer in the constructed system. This work may contribute to the design and construction of highly efficient visible-light responsive photocatalyst for sustainable energy harvesting and conversion.

In situ growth of redox-active iron-centered nanoparticles on graphene sheets for specific capacitance enhancement

A fast and facile approach is proposed to enhance the specific capacitance of N-Methyl-2-pyrrolidone (NMP)-exfoliated graphene. Redox-active nickel ferricyanide (NiFeCN) nanoparticles were grown on the surface of graphene sheets using a simple co-precipitation method. Apart from the synergetic effect of graphene as double layer capacitance and NiFeCN as pseudocapacitance in specific capacitance enhancement, the NiFeCN nanoparticles served as the spacer to prevent the graphene sheets agglomeration. The NiFeCN/graphene exhibited specific capacitance of 113.5Fg−1, which was 2 times higher than the NMP-exfoliated graphene (52Fg−1) and 6times higher than the pure NiFeCN (18Fg−1). The findings suggested the NiFeCN/graphene could be the potential candidate for supercapacitor electrode.

Label-free aptasensor for thrombin using a glassy carbon electrode modified with a graphene-porphyrin composite

We report on an electrochemical aptasensor for the ultrasensitive determination of thrombin. A glassy carbon electrode modified with a graphene-porphyrin nanocomposite exhibits excellent electrochemical activity and can be used as a redox probe in differential pulse voltammetry of the porphyrin on its surface. The thrombin aptamer is then immobilized via p-stacking interactions between aptamer and graphene and π-π stacking with porphyrin simultaneously. The resulting electrochemical aptasensor displays a linear response to thrombin in the 5–1,500 nM concentration range and with a limit of detection of 0.2 nM (at an S/N of 3). The sensor benefits from the synergetic effects of graphene (with its high conductivity and high surface area), of the porphyrin (possessing excellent electrochemical activity), and of the aptamer (with its high affinity and specificity). This kind of aptasensor conceivably represents a promising tool for bioanalytical applications.

High lithium storage performance of α-Fe 2O 3/graphene nanocomposites as lithium-ion battery anodes

Uniformly loaded α-Fe 2O 3/graphene nanocomposites are synthesized via hydrothermal routs. Enhanced lithium storage performance of lithium-ion battery anodes is realized from α-Fe 2O 3/graphene nanocomposites. Compared with pure α-Fe 2O 3 nanostructures, α-Fe 2O 3/graphene nanocomposites exhibit higher reversible capacity and better cycling performance. Their reversible capacity is up to 771 mA h g −1 at C/10 rate, and maintains 73% after 30 cycles. Such behaviors can be attributed to high electron and Li-ion conductivity, large surface area, good mechanical flexibility of graphene nanosheets and the synergetic effect of graphene and α-Fe 2O 3 nanostructures. Our results indicate that α-Fe 2O 3/graphene nanocomposites are good candidates for high performance lithium-ion battery anodes.