Showing 6 results for Graphene
A. Hasani, M. Baniadam, M. Maghrebi,
Volume 35, Issue 4 (2-2017)
Abstract
The electrochemical exfoliation of graphite via intercalation is one of the attractive methods to obtain graphene. However, presence of course graphite particles in product is the drawback of this method. In this research, the effect of adding cetyl trimethyl ammonium chloride (CTAC), on the amount of exfoliated graphene and functional groups was studied. Transmission electron microscopy, weighing, UV-vis spectroscopy and electrical conductivity were used for characterization of the products. According to results, presence of this surfactant decreases the erosion, while it increases the exfoliation of graphene flakes. However, after critical micelle concentration (CMC) of the surfactant, exfoliated weight decreased.
Z. Khosroshahi, F. Karimzadeh, M. Kharaziha,
Volume 37, Issue 2 (9-2018)
Abstract
Due to electrical properties (high electron mobility) and electrochemical characteristics (high electron transport rate), graphene-based materials have been widely applied for various scientific fields. However, due to their two-dimensional structures, these materials have low active sites for reaction. Therefore, changing from two-dimensional sheets dimensional to the three-dimensional ones could provide graphene-based materials with high specific surface and electron and mass transport particles. For these purpose, reduced graphene oxide (rGO) and polystyren (PS) aqueous solution were mixed with two different weight ratios kinetic. In this study, the three-dimensional graphene (3DG) was synthesized with graphene oxide using sacrificial PS particles. For this purpose, rGO and the PS aqueous solution were mixed with two different weight ratios of 95:5 and 85:15. Then, the 3DG-PS scaffolds were synthesized by controlling the pH value in the range of 6-8. Subsequently, PS particles were removed by immersing the synthesized scaffolds in toluene. In this research, the effect of filtering through the member filter and centrifuge on the morphology of the scaffolds was investigated. The scaffolds were characterized with X-ray diffraction and scanning electron microscopy. The results showed the formation of 3DG with a uniform distribution of porosities by using the centrifuge procedure. Moreover, the sacrificial PS particles were completely removed when the rGO to PS weight ratio was 95:5. So, 3DG with the uniform distribution of microscopy porosity could be synthesized through the sacrificial mold method and the centrifuge procedure; graphene oxide was also reduced with the PS weight ratio of 95:5. Further, based on the electrochemical evaluation of this optimized sample, as compared to the rGO , it was found that the 3DG had better electrochemical properties than the rGO. Therefore, 3DG with the optimized rGO to PS weight ratio of 95:5 could be an ideal substitute for rGO in electrochemical applications
G. Pishevarz, H. Erfan Niya, E. Zaminpayma,
Volume 37, Issue 3 (12-2018)
Abstract
Abstract: In this work, the amounts of the adsorption of conjugated polymers onto graphene/ graphene oxide were examined by reactive force-field molecular dynamics simulation. The polymers were poly(3-hexylthiophene) (P3HT) and poly(phenothiazine vinylene-polythiophene)(PTZV-PT). The length and width of the graphene sheet were 95.19 Å and 54.16 Å, respectively. The graphene oxide sheets with different oxidation percentages were considered. The molecular dynamics simulation results demonstrated a higher amount of adsorption onto graphene oxide sheets in comparison to graphene; furthermore, poly(phenothiazine vinylene-polythiophene) revealed a larger amount of adsorption in comparison with poly(3-hexylthiophene) in both functionalized groups of hydroxyl and epoxy. Also, some structural properties of polymers, such as radius of gyration of polymer and radial distribution function, were calculated at different reactive sites.
N. Bahremandi Tolou, H. R. Salimi Jazi, M. Kharaziha, N. Lisi, G. Faggio, A. Tamburrano,
Volume 39, Issue 1 (5-2020)
Abstract
In recent years, graphene has been considered in various tissue engineering applications such as nerve guide conduits because of its unique properties such as high electrical and mechanical properties, porous structure for exchange of nutritious and waste materials, biocompatible, capability of drug and growth factor delivery. In the current study, nerve guide conduits based on a 3D graphene were synthesized by induction heating chemical vapor deposition (ICVD). Graphene was synthesized on Ni foam template at 1080 ͦC. Fabricated samples were characterized by Raman analysis and Scanning Electron Microscopy. Raman analysis showed that the synthesized graphene is in the form of a turbostratic multilayered graphene with little defects. Cyclododecane (CD) as a temporary protective layer was used to remove nickel. After removing nickel, the free-standing 3D-graphene structure was coated with a polymer (PCL) by drop and dip coating methods to obtain the composite conduit. A comparison of the electromechanical results of the 3D-graphene/PCL conduit and PCL conduit indicated that firstly, grapheme increased the electrical conductivity of the composite conduit which will help promote nerve regeneration and axon growth. Secondly, tensile strength and flexibility of the 3D-graphene/PCL conduit was improved compared to the PCL conduit.
M. Khosravi , M. Mansouri, A. Gholami, Y. Yaghoubinezhad,
Volume 40, Issue 1 (5-2021)
Abstract
In this research, the effect of graphene oxide (GO) and reduced graphene oxide (RGO) nanosheets on the mechanical and microstructural properties of AISI 304 stainless steel welded joints produced by the flux-cored arc welding (FCAW) method was investigated. Light microscope, field emission scanning electron microscope (FE-SEM) equipped with energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), Raman spectroscopy, and tensile strength test were used to characterize the samples. GO was synthesized by modified Hummers’ method and reduced by hydrazine. Accordingly, the pastes of GO and RGO in different concentrations of 1, 3, and 10 mg/ml were applied in the groove. The results demonstrated that increasing the RGO concentration up to 10 mg/ml improves the tensile strength and hardness values of welded joints up to 23% and 43%, respectively. It seems that RGO nanosheets have a significant effect on the mechanical properties of the welded joints by pinning of dislocations.
N. Ghobadi, S. A. Hosseini Moradi, M. Amirzade,
Volume 40, Issue 4 (3-2022)
Abstract
In this research, cobalt ferrite powders (CoFe2O4) and cobalt ferrite/reduced graphene oxide composite (CoFe2O4/RGO) were synthesized by the co-precipitation method. The phase structure, morphology, magnetic properties, and microwave absorption properties of the produced samples were investigated through various techniques. X-ray diffraction test indicated the successful formation of pure CoFe2O4 and its composites with RGO. According to the Scanning electron microscopy (SEM) images, most pure and composite samples’ particles were formed in a semi-spherical shape. The VNA test results showed the saturation magnetization of CoFe2O4 and the composite containing 5 wt.% and 10 wt.% of RGO, 71.6, 56, and 37 emu/g, respectively. Also, the network analyzer results demonstrated the maximum reflective losses in the X-band range due to the impact of microwaves on CoFe2O4 te was -5.5 db. This amount reached 21.5 dB with the addition of 10 wt.% RGO. Also, the wave input increased from 41% for the pure CoFe2O4 to 99.5% for the sample containing 10 wt.% RGO.
