Graphene Oxide Nanopowder Research Articles

Metal-free adsorption and photodegradation methods for methylene blue dye removal using different reduction grades of graphene oxide

The release of organic pollutants and dyes into the environment by industries has had profound and harmful effects on both humans and ecosystems. Graphene oxide (GO) and its reduced form have been investigated for their effectiveness in removing pollutant dyes. GO nano-powder was synthesized using an improved version of Hummer's method and subsequently thermally reduced at various temperatures, including 125, 150, 175, and 200 °C, under vacuum conditions. In the X-ray diffraction spectra, an intense (001) diffraction peak was initially observed at 9.136° (2θ) for pristine GO. This peak gradually shifted towards higher angles as the reduction process took place and eventually disappeared when the GO was reduced at 200 °C. The intensity ratio of the D and G bands (ID/IG ratio) for GO nano-powder in the Raman spectra decreased from 0.94 to 0.76 due to the reduction process. The FTIR spectra of GO and reduced graphene oxide (rGO) also illustrated the reduction process. The bandgap of pristine GO significantly decreased from 2.31 to 0.73 eV, as determined by ultraviolet–visible (UV–Vis) diffuse reflectance spectrophotometry during the reduction process. The surface area and pore volume of both pristine GO and rGO-150 were determined using the BET (Brunauer-Emmett-Teller) and BJH (Barrett-Joyner-Halenda) methods. The results indicated an increase in the BET surface area from 6.61 to 7.86 m2/g and a corresponding enhancement in pore volume from 0.118 to 0.128 cc/g after reduction. The adsorption and photocatalytic degradation behavior of pristine GO and reduced graphene oxides (rGOs) were examined using methylene blue dye. The pristine GO demonstrated impressive adsorption capability, effectively removing the dye by 85.78 % within just 15 min and achieving nearly 97 % removal after 4 h. In contrast, the highest photocatalytic degradation of methylene blue, about 47.58 %, was attained for the rGO sample reduced at 150 °C under the illumination of visible light.

Investigation of the effect of graphene oxide nanoparticles on the structural and dielectric parameters in zinc oxide semiconductors

In this study, pure and 1%, 3% and 5% doped graphene oxide (GO) reinforced zinc oxide (ZnO) nanoparticles were synthesized by sol-gel method. The aim was to improve the electrical and dielectric properties of ZnO semiconductor metal oxide used in many electronic, optoelectronic and electrochemical technologies. FE-SEM, X-ray diffraction (XRD), Raman spectroscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy (FT-IR), were used to show the structural and morphological properties of the synthesized ZnO and GO doped ZnO nanoparticles. Impedance analysis was used to study the dielectric properties of the produced nanoparticles. XRD analysis revealed typical peaks of nGO and ZnO nanoparticles. Through the FE-SEM and XRD analysis, it was shown that the ZnO and GO nanopowders were successfully synthesized. The results revealed that ZnO-GO nanoparticles, having good dielectric constant with loss and AC conductivity values, such materials can be a good candidate for solar cells and photovoltaic devices.Graphical

Toxic Effects of Nanographene Oxide on Testes of Rats

The current study aimed to examine the effects of nanographene oxide on the testes. A total of 48 male albino rats were randomly divided into 6 groups. The first, second, third, fourth, and sixth groups were treated with graphene oxide nanopowder at 20, 30, 40, 50, and 60 mg/kg concentrations, respectively. The sixth group was considered the control group. The results indicated a significant decrease in the average testis weight of rats treated with different nanographene oxide dosages, compared to the control group. There was also a significant decrease in the level of FSH and testosterone of treated rats with nanographene oxide, while there was no significant difference in the level of LH hormone when compared to the control group. The histological examination of the testes in the treated rats indicated hemorrhage, decreased sperm count, decreased thickness of the tubular epithelium, dissociation of connective tissue between the seminiferous tubules, in addition to hematological congestion, necrosis of the tubular epithelium, divergence of the seminal tubules, absence of sperm, shattering of the seminal tubule wall and degeneration sperm-forming cells and edema formation. Using the transmission electron microscope, the findings revealed a range of cellular changes, such as the presence of two-headed spermatids, the destruction of the nucleus membrane, spermatoblasts, the destruction of the cell membrane, and the denting of the nucleus membrane. It can be concluded that the nanographene oxide at 20-60 mg/kg concentrations can have harmful effects on spermatogenesis and normal function testis in rats.

Modification of Cotton and Leather Surfaces Using Cold Atmospheric Pressure Plasma and TiO2-SiO2-Reduced Graphene Oxide Nanopowders

Surface modification of textile fabrics and leathers is very versatile and allows the products quality improvement. In this work, cotton and leather substrates were pre-treated with cold atmospheric pressure plasma (CAPP) and further coated with TiO2-SiO2-reduced graphene oxide composites in dispersion form. By using a Taguchi scheme, this research evaluated the effect of three significant parameters, i.e., the pre-treatment with CAPP, organic dispersion coating and TiO2-SiO2-reduced graphene oxide (TS/GR) composites, that may affect the morpho-structural properties and photocatalytic activity of modified cotton and leather surfaces. The characteristics of cotton/leather surfaces were evaluated by morphological, structural, optical and self-cleaning ability using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), X-ray powder diffraction (XRD), attenuated total reflection-Fourier Transform Infrared spectroscopy (ATR-FTIR) and UV-Vis spectroscopy. The self-cleaning performance of the obtained cotton and leather samples was evaluated by photocatalytic discoloration of berry juice surface stains under UV light irradiation for 12 h. The successfulness of coating formulations was proven by the SEM analysis and UV-Vis spectroscopy. The XRD patterns and ATR-FTIR spectra revealed the cellulose and collagen structures as dominant components of cotton and leather substrates. The CAPP treatment did not damage the cotton and leather structures. The photocatalytic results highlighted the potential of TiO2-SiO2-reduced graphene oxide composites in organic dispersion media, as coating formulations, for further use in the fabrication of innovative self-cleaning photocatalytic cotton and leather products.

Property Modulation of Graphene Oxide Incorporated with TiO2 for Dye-Sensitized Solar Cells.

Graphene oxide (GO) nano-powder is synthesized by the modified Hummer's method, and further thin films are deposited by using the water solution of GO through spin-coating. These films are thermally reduced along with the synthesized GO nano-powder at 50 to 200 °C in a high vacuum. Microstructural, electrical, and optical properties are expectedly controlled by thermal reduction. The electronic properties of GO are investigated by X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure. The reduction is confirmed by Raman spectroscopy. The work function and band gap of GO are tuned with the thermal reduction. The changes in properties of GO are not linear, and anomalous changes are observed for the reduction around 150 °C. Pristine and reduced GO nano-powder is incorporated into TiO2 paste to be the photoanode for dye-sensitized solar cells (DSSCs). It is observed that the performance of the fabricated cells is significantly enhanced for the GO reduced at 150 °C, and the cell exhibited a significant increment of ∼23% for the power conversion efficiency in comparison to DSSC based on an unmodified TiO2 photoanode.

Naproxen Adsorption onto Graphene Oxide Nanopowders: Equilibrium, Kinetic, and Thermodynamic Studies

Recent studies show that carbonaceous materials have gained interest because of their superior features over the alternative adsorbents. Therefore, it is of great value to synthesize novel carbonaceous adsorbents. In the present study, graphene oxide nanopowders (GON) were synthesized through a modified Hummer’s method. The material has been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) methods. Naproxen has been selected as the model pharmaceutical to investigate the adsorption performance of GON. The highest adsorption removal was found to be 65.28% under the optimum conditions (0.03 g of GON for the adsorption of 10 mg/L naproxen solution at 100 rpm mixing the speed of shaking bath). The relevant adsorption system was an exothermic, spontaneous, and chemisorption process depending on the kinetic (pseudo-first order, pseudo-second order, intraparticular, and Elovich models), equilibrium (Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Harkin-Jura, and Halsey isotherm equations), and thermodynamic parameters.

Synthesis, characterization and an application of graphene oxide nanopowder: methylene blue adsorption and comparison between experimental data and literature data

With the discovery of graphene, the necessary synthesis studies have been carried out for the use of graphene oxide (GO) as an adsorbent to remove toxic materials. In this study, GO nanopowder was synthesized to conduct methylene blue (MB) adsorption studies. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) characterization tests were used to investigate the adsorbent structure. The highest adsorption capacity was found to be 311.74 mg/g under the optimal conditions (0.5 g L−1 of adsorbent dose at 100 rpm mixing the speed of shaking bath, pH 10, and 25 °C). Kinetic mechanism and isotherm models were applied to experimental data. Pseudo-second-order kinetic model was a well fit to our experimental data. Besides, thermodynamic study revealed that adsorption process was spontaneous and exothermic. Moreover, adsorption capacity of GO nanopowder was compared to other graphene and functionalized graphene oxide for MB from aqueous solutions.

A hierarchical zeolite Beta with well-connected pores via using graphene oxide

Hierarchical zeolite Beta has been successfully synthesized by adding graphene oxide (GO) in the hydrothermal system and characterized by XRD, SEM and N2 adsorption-desorption. The results show that the mesoporous distribution of the hierarchical zeolite Beta can be adjusted in the range of 3–7 nm and the mesoporosity can be varied by changing the type and content of GO. The formation of mesoporous structure in the zeolitic particles is from that the growth of crystalline is blocked in part by GO attached onto the zeolitic crystalline surface. Compared to spherical structure of GO nanopowders, laminar structure of GO nanosheets is propitious to increase the connectivity of the mesopores in the zeolite materials.

High temperature ablation and thermo-physical properties improvement of carbon fiber reinforced composite using graphene oxide nanopowder

Ablative nanocomposites were prepared by incorporating graphene oxide (GO) nanosheets into resole type phenolic resin and then impregnating them into rayon-based carbon fabric. GO were dispersed into phenolic resin at 0.25, 0.75, and 1.25wt.% loadings using high shear mixing to insure uniform GO dispersion. The morphology and structure of graphene oxide nanosheets (synthesized by a Hummers method) and the structural, thermal and ablative properties of the samples were characterized using Fourier Transform Infrared spectroscopy(FTIR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), oxyacetylene flame test, and Thermo-Gravimetric Analysis (TGA) methods. It was found that the thermal stability and ablative properties of the GO/phenolic resin/carbon fiber composites were greatly enhanced due to the well dispersion of GO sheets in polymer matrix and the strong interfacial interaction between the GO sheets and phenolic matrix as well as layered carbon structure after pyrolysis. The specimen with 1.25wt.% GO showed the best results in the rate of ablation, thermal diffusivity and thermal stability compared to other samples. This laminate had constant thermal diffusivity at different temperatures, and improved char yield and ablation rate to about 10% and 51%, respectively.