In this study, two different methods were described for the synthesis of 2-(aryl)-3-((2-oxo-2-(2-oxo-2H-chromen-3-yl)ethyl)amino)imidazolidin-4-one derivatives under microwave irradiation. The first method was step by step method. In step by step method, 3-(2-hydrazinylacetyl)-2H-chromen-2-one and aromatic aldehydes in 1 mL of absolute ethanol were irradiated with appropriate power within 3-10 min to obtain imine products. Then, the imine products were isolated and reacted with glycine to produce the 2-(aryl)-3-((2-oxo-2-(2-oxo-2H-chromen-3-yl)ethyl)amino)imidazolidin-4-one under microwave irradiation. In the one-pot method, the graphene oxide nanosheets were applied as heterogeneous catalysts. Hence, the graphene oxide nanosheets were synthesized based on Hummer’s method. The catalyst was characterized by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and X-ray diffraction (XRD) techniques. Then, 3-(2-hydrazinylacetyl)-2H-chromen-2-one, glycine, and aromatic aldehydes were irradiated using microwave irradiation in the presence of 0.5 mol% of graphene oxide nanosheets in ethanol. The prepared catalyst showed superior reusability for seven catalytic cycles. Our results showed that the one-pot method was better than the step by step method.

In this paper, the graphene oxide nanosheets modified by benzimidazole were used as the epoxy coating reinforcing nanoparticles. In this way, after synthesizing of graphene oxide and physically adsorption of benzimidazole molecules on them, the modified graphene oxide nanosheets and the unmodified graphene oxide were dispersed in the epoxy matrix. The physical-mechanical properties of the coatings obtained were evaluated by DMTA and tensile tests. In addition, by a scanning electron microscope (SEM) the coating fractured surface morphology and the degree of nanoparticle dispersion in the coatings were studied. The results showed that the benzimidazole molecules could successfully modify the graphene oxide nanosheets surface via noncovalent bonds. Furthermore, the ultimate tensile strength, Young's modulus, strain at break, and energy at break were increased 81%, 15%, 310%, and 207%, respectively, compared to the neat epoxy coating. This improvement in physical-mechanical properties of the coating may be attributed to the better dispersion of the nanosheets in the coating as well as the stronger interactions between the nanosheets and the epoxy resin.

In this study, an efficient and facile technique for preparing graphene oxide in suspension and powder forms was presented based on a modification on Hummers'' method followed by an additional ultrasonic process. The method involved the provision of graphene oxide from graphite by reaction of potassium permanganate and sulfuric acid with stabilizing the medium complex. Furthermore, this study evaluated the functionality of graphene oxide in powder form in comparison with suspension using Fourier transform infrared spectroscopy. In addition, prepared graphene oxide powder was characterized using X-ray diffraction method for investigating the exfoliation of graphite to graphene nanosheets. Moreover, transmission electron microscopy and atomic force microscopy techniques were employed to demonstrate the structure of resulting graphene oxide in suspension form. The presence of graphene oxide nanosheets including an average thickness of about 2-4 nm was proved via microscopy observation of the prepared nanosheets.

In this study, graphene oxide nanosheets have been used for the adsorption of methylene blue, a cationic dye from aqueous solution. The physical characteristics of graphene oxide nanosheets studied using Fourier transform infrared (FTIR) and X-ray diffraction (XRD). The adsorption of the methylene blue onto the graphene oxide nanosheets has been carried out at different experimental condition such as contact time (1- 4 hours), adsorbent dosage (0.05 - 0.7 g/l), pH of solution (3 - 9) and initial concentration of dye (50 – 400 mg/l). The results show that the maximum adsorption (910 mg/g) under these conditions; adsorbent dosage of 0.05 g/l, initial concentration of 50 mg/l, two hours contact time and pH=6. The kinetic of adsorption data analyzed using three kinetic models such as elovich model, pseudo first-order model and pseudo second order model. Kinetic study indicated that the maximum adsorption was reached at two hours and follows the linear form of pseudo second-order kinetic model. The adsorption isotherm has been investigated in the pH range of 3 to 9, initial concentration of 50 to 400 mg/l and the adsorbent dosage of 0.05 to 0.7 g/l in 25 °C. The equilibrium data fitted to the Langmuir isotherm model well. Thus, graphene oxide nanosheets can be known as a good adsorbent for the adsorption of cationic pollutants.In this study, graphene oxide nanosheets have been used for the adsorption of methylene blue, a cationic dye from aqueous solution. The physical characteristics of graphene oxide nanosheets studied using Fourier transform infrared (FTIR) and X-ray diffraction (XRD). The adsorption of the methylene blue onto the graphene oxide nanosheets has been carried out at different experimental condition such as contact time (1- 4 hours), adsorbent dosage (0.05 - 0.7 g/l), pH of solution (3 - 9) and initial concentration of dye (50 – 400 mg/l). The results show that the maximum adsorption (910 mg/g) under these conditions; adsorbent dosage of 0.05 g/l, initial concentration of 50 mg/l, two hours contact time and pH=6. The kinetic of adsorption data analyzed using three kinetic models such as elovich model, pseudo first-order model and pseudo second order model. Kinetic study indicated that the maximum adsorption was reached at two hours and follows the linear form of pseudo second-order kinetic model. The adsorption isotherm has been investigated in the pH range of 3 to 9, initial concentration of 50 to 400 mg/l and the adsorbent dosage of 0.05 to 0.7 g/l in 25 °C. The equilibrium data fitted to the Langmuir isotherm model well. Thus, graphene oxide nanosheets can be known as a good adsorbent for the adsorption of cationic pollutants.Thus, graphene oxide nanosheets can be known as a good adsorbent for the adsorption of cationic pollutants.

Everyday growth of the application of Graphene, Graphene oxide, and other materials based on graphene causes a huge demand for finding commercial and straightforward methods for synthesizing this valuable compound. Today, there are several laboratory methods for synthesizing graphene oxide nanosheets that researchers around the world use. The ability to produce on a large scale and industrially with many of these methods is a significant challenge due to the use of expensive raw materials or the production of toxic substances in the production process. The presence of these poisonous substances in the production cycle creates environmental issues. This study aimed to find an easy and inexpensive way to produce graphene oxide on an industrial scale that does not produce toxic substances, or the amount of their occurrence is minimal during the production process. In this study, graphene oxide nanosheets have been synthesized successfully by a straightforward and nontoxic method that produces no hazardous materials during the synthesizing process. The samples were analyzed using several techniques: X-ray diffraction (XRD), Raman spectroscopy, UV-Visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Comparing the results with the other researchers’ works confirmed synthesizing high-quality graphene oxide nanosheets. Due to the simple and environment-friendly method, which produces no hazardous materials during the production process, the method may quickly develop for the commercial production of graphene oxide. In other words, the research proposes a new and ideal method for large-scale synthesizing graphene oxide nanosheets for commercial purposes with the lowest environmental issues.

X-ray diffraction pattern (XRD), Transmission electron microscope (TEM), Raman spectroscopy and Fourier transform infrared (FTIR) are used to characterize the structure of graphene oxide nanosheets. The results show the presence of thin graphene oxide layers, which have a suitable crystal structure with a peak of about 10 degrees and a ratio of ID/IG about 0.99. Also, by employing Kramers-Kronig (KK) relations and obtaining their refractive index, extinction coefficient and dielectric function via FTIR spectroscopy, the optical phonon modes, the transverse optical phonon (TO) and the longitudinal optical phonon (LO), of this material have been calculated. Then, the nonlinear optical (NLO) properties were obtained through the single-beam Z-scan method using a continuous wave (CW) Nd:YAG laser with a wavelength of 532 nm. The Z-scan results show that graphene oxide nanosheets have the phenomena of self-focusing and two photon absorption (TPA). In addition, a suitable figure of merit (FOM) was obtained for these nanosheets.

In this experimental investigation, a simple and efficient technique is presented for the carbonic nanostructures fabrication-in particular, Graphene Oxide (GO) and Graphene nanosheets- based on the pulsed laser ablation of graphite target inside the Cetyltrimethylammonium bromide (CTAB) (0.1 M) and liquid nitrogen environments using the pulsed nanosecond Q-switched Nd:Y3Al5O12 (Nd:YAG) laser at 532 nm. X-ray diffraction (XRD) pattern, Raman spectrum, Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and Field emission scanning electron microscopy (FE-SEM) were used to characterize the ablation products. Results exhibit that the graphene nanosheets produced in liquid nitrogen medium are multilayer, includes the largest SP2 domain size and the least structural defects. In addition, two categories of graphene nanosheets and carbon nanoparticles were observed in TEM images of produced sample in this cryogenic medium. Furthermore, XRD, FT-IR and Raman analyses indicate that graphene is oxidized in CTAB solution owing to existence of oxygen molecules in ablation environment. Our experimental results can be useful guidance toward the production of graphene nanosheets with desired attributes.

In this research,nanocomposite coatings based on epoxy containing pristine graphene oxide and starch-modified graphene oxide are prepared and characterized by Fourier transfer infrared spectroscopy, andtheir crosslinking behavior is studied using nonisothermal differential scanning calorimetry.These nanocomposites, because of having platelet-like nanomaterials inside and their organic origin, can be applied as coating on metal surface in diverse industries.The reason behind using starch was its natural basis and abundance of hydroxyl groups in its structure which can take part in crosslinking reaction with epoxide. Neat epoxy systems having amine curing agent, and nanocomposites containing epoxy, amine curing agent, andpristine or starch-modified graphene oxide nanosheets were cure at different heating rates to assess their curing behavior. Change in hearing rate of test caused change in onset and peak temperature of the exotherm curves and consequently heat of reaction changed. It was observed that the presence of the graphene oxide nanosheets hindered the crosslinking reactions, while surface modification of them with starch natural polymer compensated for such a hindrance via catalytic role of starch, and increased crosslink density of system.

Two-dimensional nanomaterials have special capabilities in gas sensors due to features such as high surface-to-volume ratio and multiple active sites. In this research, molybdenum disulfide nanosheets, graphene oxide and their composites were prepared by liquid exfoliation, Hammers, and sonochemical methods, respectively. Physical properties of the prepared nanomaterials were evaluated using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Then the humidity sensors were prepared based on these materials on Si/SiO2 substrates and using copper electrodes. Due to the different types of carriers in graphene oxide and molybdenum disulfide (p-type and n-type, respectively), the current changes in different moisture percentages were obtained differently for these two sensors, and the behavior of the sensor based on the composite of these two materials was more similar to the behavior of graphene. The recovery time and response time of all three sensors were measured within 20 seconds. The results showed that the composite of graphene oxide and molybdenum disulfide, has a better humidity sensor behaviour rather than molybdenum disulfide nanosheets.

By varying the level of graphene's surface oxidation in this paper, the thickness of the interphase region was altered, and its influence on the conductivity was investigated. Due to the similarity of water-based epoxy chemical groups with graphene oxide oxygen groups, the interphase region was reinforced. Infrared spectroscopy and thermal gravimetry were performed to evaluate the graphene oxide synthesis, and Raman spectroscopy was also performed to investigate the structural defects on graphene sheets. At first glance, based on the interphase region theory, it is expected that by increasing the oxidation rate of graphene nanosheets, the electrical conductivity of polymeric coatings will increase, and the percolation threshold will decrease. On the other hand, due to increased oxidation, the structural defect on graphene nanosheets increases, and the conductivity of the coatings is expected to decrease. Due to the opposite effect of the two factors mentioned above, the effectiveness of nanocomposite samples was studied, and the impressment of each factor was investigated in this project.