Effect Of Reduced Graphene Oxide Research Articles

The permeability, mechanical and snow melting performance of graphene composite conductive-pervious concrete

Snow on the roads poses a serious threat to the safety of vehicles, and the traffic system will be paralyzed under harsh conditions. In this study, composite conductive concrete with straight pervious channels were prepared by using carbon fiber, steel fiber and reduced graphene oxide (RGO) as conductive materials to remove snow from roads as soon as possible. The effects of RGO on the workability, mechanical properties and electrical conductivity of composite conductive concrete were studied, and the influence of pervious channels on snow melting efficiency and energy consumption of composite conductive concrete snow melting slabs were analyzed. Results showed that the permeability coefficient of composite conductive concrete with pervious channels reached 6.28 mm/s, meeting the requirements of pavement pervious concrete. For the RGO content of 0.09 % cement mass, the mechanical properties and conductivity of the composite conductive concrete were improved because of the filling effect of nano-RGO on the matrix, while it exerted adverse effects when RGO contents were over 0.09 %. The pervious channels weakened the mechanical and conductive properties of composite conductive concrete. However, compared with the composite conductive concrete without straight pervious channels, the snow melting time and energy consumption were reduced by more than 10 % and 15 %, respectively.

Effects of polyvinylpyrrolidone as a dispersant agent of reduced graphene oxide on the properties of carbon fiber-reinforced polymer composites

The electrical and mechanical properties of carbon fiber-reinforced polymer (CFRP) composites have a close dependence on the use of modifiers like polyvinylpyrrolidone (PVP), as well as on the processing techniques to disperse functional charges such as graphene-related materials into the epoxy base. In the present work, reduced graphene oxide (RGO), prepared by a natural antioxidant agent, astaxanthin, was used as a filler material in the epoxy matrix of the carbon fiber composites. The astaxanthin reduction leads to an increase in the sp2 ordering in RGO; some residual epoxy and C-O groups that enhance the interaction with the epoxy matrix remain after reduction. The effects of RGO and PVP-modified RGO (PVP-RGO) fillers with different contents (0.05, 0.1, and 0.15% wt.) on the electrical conductivity, bending properties, and dynamic mechanical properties of CFRP were investigated. The incorporation of 0.15 wt.% RGO with and without PVP-modification, leads to through-the-thickness (Z-direction testing) conductivity values 7.4 and 9.6 times higher than those of the neat composite, respectively. The conductivity tests indicate that the RGO/epoxy composite behaves as a continuous conductor due to the formation of agglomerates of RGO within the matrix, while at the added contents of the PVP-RGO filler, the composite is below the percolation threshold, then conducting by electron tunneling, due to a better dispersion of the PVP-RGO filler within the epoxy matrix. The dynamic mechanical analysis shows that the glass transition temperature is indicative of the interactions among the filler, the epoxy matrix, and the carbon fiber, that is, the PVP-RGO filler increases the chain mobility due to its higher dispersion in the matrix. While Tg of the neat epoxy/CFRP composite is 92.5°C, a minimum Tg of 88.5°C was achieved with a 0.10 % wt. PVP-RGO filler contents, and a maximum Tg of 94.5°C with a 0.15 % wt. of RGO filler amount. For constant filler content (0.15 wt.%), CFRP composite containing RGO and PVP-modified RGO exhibited 9.73% and 13.87% increase in flexural strength values, respectively, compared to the neat composite. The bending test revealed that PVP modification to RGO is beneficial to improve flexural strength of CFRP composites.

Effects of three graphene-based materials on the growth and photosynthesis of Brassica napus L.

The environmental safety and threats of graphene-based materials (GBMs) to the agroecosystem have attracted increasing attention in recent years. However, the mechanisms underlying the effects of GBMs on plants remain unclear. Here, we investigated the phytotoxicity of reduced graphene oxide (RGO), graphene oxide (GO) and amine-functionalized graphene (G-NH2) on Brassica napus L. The results revealed that RGO impaired photosynthesis mainly by decreasing the chlorophyll content and Rubisco activity. A further gene-level analysis suggested that this effect of RGO might be due to its toxicity on sulfate transmembrane transporter and nitrogen metabolism, which ultimately led to nutrient imbalance. However, GO directly damaged the photosystem by disrupting the chloroplast structure, and a decrease in Rubisco activity indicated that GO also inhibits carbon fixation. Further gene-level analysis demonstrated that GO has toxicity on the chloroplast membrane, photosystem, photosynthethic electron transport and F-type ATPase. In addition, G-NH2 at 10–1000 mg L−1 showed no significant toxicity. These findings shed light on the potential mechanism for the toxicity of GBMs on plants for risk assessment.

A Novel Alumina-Magnesium oxide- Reduced Graphene Composite: Synthesis and Characterizations

A novel new alumina-magnesium oxide with reinforced of reduced graphene oxide (RGO) composite materials have been synthesized by using a horizontal high energy planetary ball milling process. The composite has very high density, improved mechanical properties, retaining strength under higher temperatures, and high thermal conductivity. Al2O3-MgO-RGO composites can be used as a novel material for many industrial applications. The effect of RGO in the combination of Al2O3 and MgO have a potential scope in several demanding fields, including automobile, aerospace, defenses, sports, electronics, bio-medical, and other industrial purposes. The prepared composites have been studied by Xray diffraction (XRD), Field emission scanning electron microscopy (FESEM), micro Raman spectroscopy, Transmission electron microscope, Automatic density meter, Particle size analyzer.

Non-aligned ZnO nanowires composited with reduced graphene oxide and single-walled carbon nanotubes for highly responsive UV–visible photodetectors

A comprehensive comparison study of the UV–visible photoresponse properties of non-aligned carbothermal ZnO nanowires (ZNWs) composited with reduced graphene oxide (RGO) and single-walled carbon nanotubes (SWCNTs) is presented. The RGO/ZNWs composites (GZWs) and SWCNTs/ZNWs composites (CZWs) have been successfully synthetized through UV-assisted photochemical reduction of GO in ZNWs suspension and ultrasonic stirring technology, respectively. The optimal contents of RGO and SWCNTs incorporated into ZNWs were determined for achieving maximum photoresponse, respectively. Experimentally, the optimal GZWs and CZWs exhibit significant enhancement in photoelectric properties than pure ZNWs. It is demonstrated that the GZWs-based photodetector has higher photoresponsivity (∼16 AW-1) than CZWs-based photodetector under low UV irradiation (<10 μWcm−2) and at 1.0 V bias, while the CZWs-based photodetector has higher on/off current ratio (8.41 × 104) and faster response time (1.99 s of rise-time and 0.39 s of decay-time) than GZWs-based one. The detail physics mechanism on the effects of RGO and SWCNTs on photoelectric characteristics of ZNWs is presented with the interface charge transfer due to the chemisorption and photo-desorption of oxygen.

The Influence of Space Restriction on the Mechanical Properties of Isotactic Polypropylene/Reduced Graphene Oxide Nanocomposite Injection Bars

Isotactic polypropylene (iPP)/reduced graphene oxide (RGO) nanocomposite bars were prepared by injection molding and the effects of RGO on the iPP matrix were investigated via differential scanning calorimetry, two dimensional wide angle X-ray diffraction (2D WAXD) and small angle X-ray scattering (2D SAXS) techniques. It is demonstrated that RGO is an effective nucleation agent for iPP and the incorporation of RGO can enhance the degree of orientation of iPP crystals at flow direction. Furthermore, the orientation of iPP chains at flow direction intensifies with the increase of RGO contents, which can be attributed to that RGO obstructed the motion of orientated polymer chains. Although the enhancement effect is weaker than that of High density polyethylene (HDPE)/RGO nanocomposites with epitaxial crystallization, the mechanical properties of iPP/RGO nanocomposites can also be improved apparently.

The influence of epitaxial crystallization on the mechanical properties of a high density polyethylene/reduced graphene oxide nanocomposite injection bar

High density polyethylene (HDPE)/reduced graphene oxide (RGO) nanocomposite bars were prepared by injection molding and the effects of RGO on the HDPE matrix were investigated.

Reduced graphene oxide enhances the crystallization and orientation of poly(ε-caprolactone)

Poly(ε-caprolactone) (PCL)/reduced graphene oxide (RGO) nanocomposite bars were prepared by injection molding, and the effects of RGO on the PCL matrix were investigated. Differential scanning calorimeter and polarized optical microscopy results demonstrated that RGO was an effective nucleation agent for PCL. Two-dimensional wide angle X-ray diffraction results showed that the incorporation of RGO can enhance the orientation degree of PCL crystals in the flow direction and did not influence the crystal structure of PCL. Two-dimensional small angle X-ray scattering results confirmed that the orientation of PCL chains in the flow direction was enhanced with the increase of RGO content, which was attributed to that RGO obstructed the motion of polymer chains. These results indicated that the incorporation of RGO can enhance the crystallization and orientation of PCL matrix, which was the major factor for the improvement of mechanical properties.

Characterization of laser-induced ultrasound signal by reduced graphene oxide thickness and laser intensity

A nanosecond pulse laser generates acoustic waves on a water-material interface. The absorbed beam energy heats and thermoelastically expands the material. The thermoelastic stress of a material is dependent on its absorbance and expansion coefficient. In this work, we used a composite of reduced graphene oxide (RGO) and aluminum thin film to increase the efficiency of conversion from beamed energy to thermoelastic stress. A laser shadowgraph showed enhanced acoustic waves propagating at ~1,500 m/s under water. The effect of RGO on ultrasound generation is examined for different thicknesses of RGO at several laser fluences. The pressure of laser-induced ultrasound on the RGO–aluminum composite was measured to be up to 59 times greater than that produced with an aluminum film alone, and the frequency of laser-induced ultrasound was determined by the thermoelastic response. The strong intensity and broad bandwidth of the laser-induced acoustic wave suggested enhanced repetition time and resolution required for biomedical imaging.

Effect of reduced graphene oxide on the properties of an activated carbon cloth/polyaniline flexible electrode for supercapacitor application

Reduced graphene oxide (RGO) is synthesized and added in situ into the reaction system of polyaniline (PANI) electrodeposition using activated carbon cloth (ACC) as the substrate. The effect of RGO on the morphology, structure, and electrochemical properties of the ACC/PANI composite is investigated. A more compact and uniform layer of PANI film is observed via scanning electronic microscopy after the addition of RGO. Raman spectroscopy shows that RGO has been simultaneously deposited with PANI onto the surface of ACC. X-ray photoelectron spectroscopy reveals that the sample with RGO exhibits a higher sulfur-to-nitrogen ratio. The reversibility of the redox reaction of PANI is improved, as confirmed via cyclic voltammetry. The electrochemical impedance spectroscopy data shows that the introduction of RGO lowers the charge-transfer resistance of ACC/PANI, meanwhile, improves the coverage percentage of PANI on the ACC surface to a significant extent, primarily because of the interactions between RGO, ACC, and PANI. The as-prepared composite with RGO shows improved rate performance and cyclability as a supercapacitor electrode.