Combination Of Reduced Graphene Oxide Research Articles

Synergistic influence of MWCNTs/RGO on low-velocity impact response and mechanical properties of carbon fiber/epoxy composite

Nanoparticles can be used to enhance and improve the mechanical properties and low-velocity impact response of carbon fiber-reinforced polymer (CFRP) composites both simultaneously and individually. Also, the synergistic influence of two nanoparticles can be improved the mechanical properties and low-velocity impact response of CFRP composites. In this paper, the effects of reduced graphene oxide (RGO) and multi-walled carbon nanotubes (MWCNTs) on the mechanical properties, low-velocity impact response and damage area of epoxy/fiber carbon composites are investigated both simultaneously and individually. Composite specimens are fabricated with 0.4 weight percentages (wt.%) of RGO, 0.06 wt.% of MWCNTs individually, and a combination of RGO and MWCNTs with 0.6 and 0.06 wt.%, respectively. For comparison of the results, the neat epoxy specimens are fabricated and also tested. Direct homogenization technique is applied for preparation of nanocomposite mixture and then each layer of carbon fiber reinforced nanocomposite is fabricated using a hand lay-up process. Tensile modulus, tensile strength, variations of load, displacement, velocity, and absorbed energy of specimens versus time are obtained. For specimens with MWCNTs/RGO tensile modulus and tensile strength increased by about 21.30% and 17.12%, respectively, and the load peak increased by 15.15% at 1 J, 13.35% at 2 J, 39.62% at 3 J, and 39.62% at 3 J. It is concluded that the synergistic influence of MWCNTs and RGO on the results is more significant and has a higher effect on the impact responses. After the impact tests, Optical microscopy and SEM method are used to analyze fracture surfaces.

Developing the Ternary ZnO Doped MoS2 Nanostructures Grafted on CNT and Reduced Graphene Oxide (RGO) for Photocatalytic Degradation of Aniline

Transition metal sulfide semiconductors have achieved significant attention in the field of photocatalysis and degradation of pollutants. MoS2 with a two dimensional (2D) layered structure, a narrow bandgap and the ability of getting excited while being exposed to visible light, has demonstrated great potential in visible-light-driven photocatalysts. However, it possesses fast-paced recombination of charges. In this study, the coupled MoS2 nanosheets were synthesized with ZnO nanorods to develop the heterojunctions photocatalyst in order to obtain superior photoactivity. The charge transfer in this composite is not adequate to achieve desirable activity. Therefore, heterojunction was modified by reduced graphene oxide (RGO) nanosheets and carbon nanotubes (CNTs) to develop the RGO/ZnO/MoS2 and CNTs/ZnO/MoS2 ternary nanocomposites. The structure, morphology, composition, optical and photocatalytic properties of the as-fabricated samples were characterized through X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Energy-Dispersive X-ray (EDX), elemental mapping, Photoluminescence (PL), Ultraviolet–Visible spectroscopy (UV-VIS), and Brunauer-Emmett-Teller (BET) techniques. The photo-catalytic performance of all samples was evaluated through photodegradation of aniline in aqueous solution. The combination of RGO or CNTs into the ZnO/MoS2 greatly promoted the catalytic activity. However, the resulting RGO/ZnO/MoS2 ternary nanocomposites showed appreciably increased catalytic performance, faster than that of CNTs/ZnO/MoS2. Charge carrier transfer studies, the BET surface area analysis, and the optical studies confirmed this superiority. The role of operational variables namely, solution pH, catalyst dosage amount, and initial concentration of aniline was then investigated for obtaining maximum degradation. Complete degradation was observed, in the case of pH = 4, catalyst dosage of 0.7 g/L and aniline concentration of 80 ppm, and light intensity of 100 W. According to the results of trapping experiments, hydroxyl radical was found to be the main active species in the photocatalytic reaction. Meanwhile, a plausible mechanism was proposed for describing the degradation of aniline upon ternary composite. Moreover, the catalyst showed excellent reusability and stability after five consecutive cycles due to the synergistic effect between its components. Total-Organic-Carbon concentration (TOC) results suggested that complete mineralization of aniline occurred after 210 min of irradiation. Finally, a real petrochemical wastewater sample was evaluated for testing the catalytic ability of the as-fabricated composites in real case studies and it was observed that the process successfully quenched 100% and 93% of Chemical Oxygen Demand (COD) and TOC in the wastewater, respectively.

Effect of the carbon loading on the structural and photocatalytic properties of reduced graphene oxide-TiO2 nanocomposites prepared by hydrothermal synthesis

This work deals with the preparation of reduced graphene oxide (RGO)-TiO2 composites by a one-step hydrothermal treatment. The effect of the RGO loading on both the structural properties and photocatalytic behavior of RGO-TiO2 is deeply addressed herein. The hydrothermal treatment promoted the reduction of graphene oxide, crystallization of TiO2 into anatase, and anchoring of TiO2 nanoparticles on RGO sheets. It was observed that the prepared anatase particles showed sizes below 10nm, whereas the RGO sheets displayed thicknesses smaller than 1nm. The use of RGO at concentrations up to 15wt% greatly increased the specific surface area of RGO-TiO2. It was demonstrated that the combination of RGO and TiO2 gives rise to materials with improved photocatalytic properties and tailored structural properties. The composite with the highest photoactivity was the one containing an RGO loading of 1wt%; this composite displayed a photocatalytic rate constant about 9.5 times higher than that evaluated for pure TiO2. This behavior may be related to the stacking of RGO nanosheets when its concentration is above 1wt%. Moreover, the addition of RGO in excess may prevent the activation of the TiO2 surface by UV light and also decrease the lifetime of the photogenerated electron-hole pairs. Therefore, it appears that 1wt% is the optimal loading of RGO to obtain a close interfacial contact between RGO and TiO2, leading to both an effective activation of TiO2 by UV radiation and an enhanced charge transfer between RGO and TiO2.

Ethanol detection using composite based on reduced graphene oxide and CuO hierarchical structure under wet atmosphere

Semiconductor metal oxides have been used for detecting volatile organic compounds (VOCs). However, these materials present a poor performance in humidity. Here, we report the effect of reduced graphene oxide (RGO) on the ethanol-sensing of CuO under dry and in the relative humidity range of 36–90%. For this purpose, RGO-CuO composites and CuO were synthesized by a one-step microwave-assisted synthesis. The VOCs sensing were performed at the range of 150–350 °C to acetone, benzene, ethanol, methanol, and m-xylene. The RGO-CuO composites exhibited enhanced ethanol sensing when compared with pure CuO at the optimal operating temperature of 250 °C. In addition, the optimal RGO content resulted in an enhanced selectivity and high sensitivity compared to pure CuO. The enhanced ethanol sensing performance of RGO-CuO was attributed to the RGO/CuO heterojunction. Thus, the combination of RGO and p-type CuO semiconductor can be a promising for VOCs detection under wet conditions.

Microwave absorption properties of reduced graphene oxide strontium hexaferrite/poly(methyl methacrylate) composites

The key factors to consider when designing microwave absorber materials for eradication of electromagnetic (EM) pollution are absorption of incident EM waves and good impedance matching. By keeping these things in mind, flexible microwave absorber composite films can be fabricated by simple gel casting techniques using reduced graphene oxide (RGO) and strontium ferrite (SF) in a poly(methyl methacrylate) (PMMA) matrix. SF nanoparticles are synthesized by the well known sol–gel method. Subsequently, reduced graphene oxide (RGO) and SF nanocomposite (RGOSF) are prepared through a chemical reduction method using hydrazine. The structure, morphology, chemical composition, thermal stability and magnetic properties of the nanocomposite are characterized in detail by various techniques. The SF particles are found to be nearly 500 nm and decorated on RGO sheets as revealed by field emission scanning electron microscopy and transmission electron microscopy analysis. Fourier transform infrared and and Raman spectroscopy clearly show the presence of SF in the graphene sheet by the lower peak positions. Finally, ternary polymer composites of RGO/SF/PMMA are prepared by an in situ polymerization method. Magnetic and dielectric studies of the composite reveal that the presence of RGO/SF/PMMA lead to polarization effects contributing to dielectric loss. Also, RGO surrounding SF provides a conductive network in the polymer matrix which is in turn responsible for the magnetic loss in the composite. Thus, the permittivity as well as the permeability of the composite can be controlled by an appropriate combination of RGO and SF in PMMA. More than 99% absorption efficiency is achieved by a suitable combination of magneto-dielectric coupling in the X-band frequency range by incorporating 9 wt% of RGO and 1 wt% of SF in the polymer matrix.

Pulsed-Electromagnetic-Field-Assisted Reduced Graphene Oxide Substrates for Multidifferentiation of Human Mesenchymal Stem Cells.

Electromagnetic fields (EMFs) can modulate cell proliferation, DNA replication, wound healing, cytokine expression, and the differentiation of mesenchymal stem cells (MSCs). Graphene, a 2D crystal of sp(2) -hybridized carbon atoms, has entered the spotlight in cell and tissue engineering research. However, a combination of graphene and EMFs has never been applied in tissue engineering. This study combines reduced graphene oxide (RGO) and pulsed EMFs (PEMFs) on the osteogenesis and neurogenesis of MSCs. First, the chemical properties of RGO are measured. After evaluation, the RGO is adsorbed onto glass, and its morphological and electrical properties are investigated. Next, an in vitro study is conducted using human alveolar bone marrow stem cells (hABMSCs). Their cell viability, cell adhesion, and extracellular matrix (ECM) formation are increased by RGO and PEMFs. The combination of RGO and PEMFs enhances osteogenic differentiation. Together, RGO and PEMFs enhance the neurogenic and adipogenic differentiation of hABMSCs. Moreover, in a DNA microarray analysis, the combination of RGO and PEMFs synergically increases ECM formation, membrane proteins, and metabolism. The combination of RGO and PEMFs is expected to be an efficient platform for stem cell and tissue engineering.

A new Methimazole sensor based on nanocomposite of CdS NPs–RGO/IL–carbon paste electrode using differential FFT continuous linear sweep voltammetry

A Methimazole sensor was designed and constructed based on nanocomposite of carbon, ionic liquid, reduced graphene oxide (RGO) and CdS nanoparticles. The sensor signal was obtained by Differential FFT continuous linear sweep voltammetry (DFFTCLSV) technique. The potential waveform contains two sections, preconcentration potential and potential ramp. In this detection technique, after subtracting the background current from noise, the electrode response was calculated, based on partial and total charge exchanges at the electrode surface. The combination of RGO and CdS nanoparticles can catalyze the electron transfer, which outcomes of the amplification of the sensor signal. The result showed that the sensor response was proportional to the concentrations of Methimazole in the range of 2.0 to 300nM, with a detection limit of 5.5×10−10M. The sensor showed good reproducibility, long-term of usage stability and accuracy. The characterization of the sensor surface was studied by atomic force Microscopy and Electrochemical Impedance Spectroscopy. Moreover, the proposed sensor exhibited good accuracy, and R.S.D value of 2.82%, and the response time of less than 7s.