Fabrication and Reduction of Graphene Oxide via Hammer Method: Investigation of Structural and Optical Properties

This study investigates the synthesis and characterization of graphene oxide (GO) and its reduced form, reduced graphene oxide (rGO), focusing on their structural, physicochemical and electrochemical properties. Graphene oxide was synthesized from graphite flakes using the modified Hummer’s method, and hydrothermal reduction with ascorbic acid, which was employed to convert GO into rGO, forming a two-dimensional structure with a high surface area. The structural transformations were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM), which revealed a significant reduction in interlayer spacing and restoration of the [Formula: see text] hybridized carbon network in rGO, confirming the successful reduction of GO. Chemical modifications were characterized through Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy and X-ray photoelectron spectroscopy (XPS). These techniques demonstrated a marked decrease in oxygen-containing functional groups in rGO, indicating effective reduction and restoration of graphitic structure. Electrochemical studies using cyclic voltammetry demonstrated that rGO-modified carbon paste electrodes (rGO/MCPE) offer superior sensitivity and enhanced electron transfer efficiency. The effects of scan rate, concentration and pH were also evaluated, underscoring its potential for high-sensitivity detection applications. These findings highlight the potential applications of GO and rGO in electrochemical sensors, particularly for detecting biomolecules like serotonin, as well as in energy storage devices such as supercapacitors and batteries, where their high surface area and conductivity offer significant advantages.

Graphene oxide (GO) and reduced graphene oxide (RGO) nanostructures were synthesized using a novel method of CO gas flow under ambient pressure and at several temperatures. The produced samples of GO and RGO were structurally, chemically and optically characterized and the results were analyzed using the techniques of UV–Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, field-effect scanning electron microscopy (FE-SEM), and sheet resistance measurements. Thermo-gravimetric analysis, and FTIR indicated the successful preparation of GO and RGO. FE-SEM was used to demonstrate the layer structure of GO and RGO nanostructures. The band gap energy (Eg) of the samples was estimated through the optical absorption spectra of GO and RGOs recorded between 200 and 1100 nm wavelengths using UV–Vis spectroscopy. The results are in good agreement with the data determined by other workers. Sheet resistance of RGO shows a decreasing trend versus annealing reduced temperature. This behavior is in accordance with variation of c-axis parameter with temperature which can be suggested to be due to the removal of water molecules and oxygen-containing functional groups between the carbon layers of the GO. Removing of the latter components may results in decreasing the distance between the graphene nano-layers.

Graphene oxide (GO) and reduced graphene oxide (RGO) are known to have superior properties for various applications. This work compares the properties of GO and RGO with graphite. GO was prepared by using Improved Hummer’s method whereas the produced GO was subjected to chemical reduction with the use of hydrazine hydrate. Graphite, GO and RGO had different morphologies, quality, functionalized groups, UV-Vis absorption peaks and crystallinity. With the removal of oxygen-containing functional group during reduction for RGO, the quality of samples was decreased due to higher intensity of D band than G band was seen in Raman results. In addition, platelet-like surface can be observed on the surface of graphite as compared to GO and RGO where wrinkled and layered flakes, and crumpled thin sheets were observed on GO and RGO surface respectively. Fourier Transform Infra-Red (FTIR) analysis showed the presence of abundant oxygen-containing functional groups in GO as compared to RGO and graphite. The characteristic peaks at 26.62°, 9.03° and 24.10° for graphite, GO and RGO, respectively, can be detected from X-Ray diffraction (XRD). Furthermore, the reduction also caused red shift at 279nm from 238nm, as obtained from ultraviolet visible (UV-Vis) analysis. The results proved that GO was successfully oxidized from graphite whereas RGO was effectively reduced from GO.

Influence of temperature variations on the dielectric parameters of thermally reduced graphene oxide

Preparation and characterization of sodium carboxymethyl cellulose/silk fibroin/graphene oxide nanocomposite films

Graphene oxide (GO) was synthesized from graphite via a modified Hummer's method, followed by thermal and chemical reductions to produce reduced graphene oxide (RGO) samples at various temperatures. A suite of characterization techniques including Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), UV-Visible Spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Hall effect measurements were employed to assess the structural, morphological, optical, and electrical properties of the samples. FTIR analysis confirmed the successful functionalization of graphite to GO and subsequent reduction to reduced graphene oxide, with peak intensities decreasing as the reduction temperature increased. UV-visible spectroscopy of GO showed a maximum absorption at 235 nm which confirmed the synthesis of GO while the reduction revealed a notable red shift in absorption peaks with increasing annealing temperature, and that signified a reduction in bandgap. XRD analyses demonstrated the removal of oxygen functional groups. The X-ray diffraction (XRD) analysis of GO showed diffraction at 2θ = 10.74° which revealed a fully oxidized graphene oxide with oxygen-containing functional groups, and hence an increase in interlayer spacing (d002) from 3.341 Å (graphite) to 8.228 Å (GO). Upon reduction, there is a gradual decrease in d002 from 8.228 Å (GO) to 3.387 Å (HRGO300), suggesting the gradual removal of intercalated oxygen molecules, and hence the gradual restoration of sp2 hybridisation in graphene. The EDS analysis revealed an increase in the carbon-to-oxygen (C/O) ratio from 1.78 in GO to 2.75 in HRGO300 as the annealing temperature for the reduction process increased which further confirmed the removal of oxygen functional groups. The Hall effect data showed hole mobility of 4.634 x101 (GO), 4.831 x101 (HRGO200), and 5.462 x100 (HRGO300) with conductivities of 8.985 x10-5 (GO), 1.087 x100 (HRGO200) and 1.791 x101 1/Ω cm, suggesting an increase in conductivity as the annealing temperature increased as revealed in the EDS. Out of the three samples identified as hole transport materials, the sample HRGO300 with the highest C/O ratio of 2.75 has the highest conductivity, and hence most suitable for application as hole transport material in perovskite solar cell.

Three-dimensional (3D) graphene networks are performance boosters for functional nanostructures in energy-related fields. Although tremendous intriguing nanostructures-decorated 3D graphene network...

The current research reports a cost-effective, efficient ad green reducing agent (L-cysteine) to reduce the graphene oxide (GO) for large-scale reduced graphene oxide (rGO) synthesis. Fabrication of rGO was performed by the reduction of GO using different concentrations from L-cysteine. Synthesis of rGO was noticed by change in color of GO solution from brown to black. For additional confirmation, the structural, morphological, optical and thermal properties of synthesized rGO were analyzed using powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), energy dispersive X-ray Spectroscopy (EDX) atomic force microscopy (AFM), thermogravimetric analysis (TGA) and ultraviolet-visible spectrophotometer (UV-Vis). The XRD, FTIR and EDS results showed the oxygen-containing groups such as hydroxyl, carbonyl, and epoxy. The UV-Vis spectrum for GO exhibited an absorbance peak at 233 nm which undergoes a red shift of the absorbance peak to 265, 273 and 278 nm due to reduction of GO to rGO using 5, 8 and 10 mg/L of L-cysteine respectively. XRD patterns demonstrated the disappearance of the characteristics peak of GO (11.1) and reinforced this appearance of peak around ~26, indicating the efficient reduction of GO and restoration of graphene sp2 hybridized structure. Furthermore, FTIR spectroscopy showed the gradual disappearance of band at 1745 cm-1 assigned to GO as L-cysteine concentration was increased. The thermal stability of the GO was much lower than those of all the rGO powders where the increased concentration of L-cysteine resulted in enhanced more thermal stability and higher C/O ratio in rGO. The SEM images confirmed the successful structurally exfoliation of two dimensional rGO sheets and showed the folded, curled and flake-like morphology of the graphene nanosheets.

Utilization of green reductant Thuja Orientalis for reduction of GO to RGO

Water soluble graphene oxide nanoplatelets and reduced graphene oxide were prepared from highly oriented pyrolytic graphite (HOPG) and from graphite waste powder. This graphite waste has been used to reuse an industrial waste product and therefore, to reduce production cost of the graphene. A chemical oxidation method was used for the graphene oxide preparation followed by sonication. The reduced graphene oxide was obtained by a graphene oxide nanoplatelets chemical reduction. Characterisation was performed using Fourier transform infrared (FTIR), X-ray diffraction (XRD), Raman spectroscopy and atomic force microscopy (AFM).

Boosting CO2 Conversion with Terminal Alkynes by Molecular Architecture of Graphene Oxide-Supported Ag Nanoparticles

BackgroundGraphene holds great promise for potential use in next-generation electronic and photonic devices due to its unique high carrier mobility, good optical transparency, large surface area, and biocompatibility. The aim of this study was to investigate the antibacterial effects of graphene oxide (GO) and reduced graphene oxide (rGO) in Pseudomonas aeruginosa. In this work, we used a novel reducing agent, betamercaptoethanol (BME), for synthesis of graphene to avoid the use of toxic materials. To uncover the impacts of GO and rGO on human health, the antibacterial activity of two types of graphene-based material toward a bacterial model P. aeruginosa was studied and compared.MethodsThe synthesized GO and rGO was characterized by ultraviolet-visible absorption spectroscopy, particle-size analyzer, X-ray diffraction, scanning electron microscopy and Raman spectroscopy. Further, to explain the antimicrobial activity of graphene oxide and reduced graphene oxide, we employed various assays, such as cell growth, cell viability, reactive oxygen species generation, and DNA fragmentation.ResultsUltraviolet-visible spectra of the samples confirmed the transition of GO into graphene. Dynamic light-scattering analyses showed the average size among the two types of graphene materials. X-ray diffraction data validated the structure of graphene sheets, and high-resolution scanning electron microscopy was employed to investigate the morphologies of prepared graphene. Raman spectroscopy data indicated the removal of oxygen-containing functional groups from the surface of GO and the formation of graphene. The exposure of cells to GO and rGO induced the production of superoxide radical anion and loss of cell viability. Results suggest that the antibacterial activities are contributed to by loss of cell viability, induced oxidative stress, and DNA fragmentation.ConclusionThe antibacterial activities of GO and rGO against P. aeruginosa were compared. The loss of P. aeruginosa viability increased in a dose- and time-dependent manner. Exposure to GO and rGO induced significant production of superoxide radical anion compared to control. GO and rGO showed dose-dependent antibacterial activity against P. aeruginosa cells through the generation of reactive oxygen species, leading to cell death, which was further confirmed through resulting nuclear fragmentation. The data presented here are novel in that they prove that GO and rGO are effective bactericidal agents against P. aeruginosa, which would be used as a future antibacterial agent.

Graphene oxide (GO) has been synthesized via modified Hummer’s method with graphite powder as a starting material. The synthesized reduced graphene oxide (rGO) was prepared by GO as a precursor. Synthesis of rGO-NS was performed by hydrothermal method using a dopant thiourea as nitrogen (N) and sulphur (S) donors with the ratio of GO: thiourea = 1:10, 1:15, and 1:20 (w/w), respectively. Characterization using Fourier Transform Infra-Red (FTIR) spectroscopy shows several peaks that have an agreement with −OH, C=O, C=C, C-OH, and C-O functional groups for GO and absorption peaks of −OH, C=C, and CO functional groups for rGO with different intensity, while modified materials of variation rGO-NS emerged typical absorptions of −OH, C=C, C=N, C-N, and C-S functional groups. GO and rGO material that have been analysed using X-Ray Diffraction (XRD) shows a dominant peak at 2θ 10.77° (001) and 24.97° (002), respectively. While the distance between layers (dSpacing) on rGO (3,56 Å) was lower than GO (8,22 Å). Compared to rGO, XRD analysis also shows that the addition of N and S on GO structure caused shifting of 2θ in 23,73°-24,06° (002) and calculated dspacing of rGO-NS is found to be 3,70 Å−3,74 Å. Morphological observation of rGO-NS using Scanning Electron Microscopy (SEM) shows that rGO-NS is a thin transparent sheets formed because the exfoliation process of GO material.

Comparative study of deoxygenation behavior for graphene oxide with different oxidation degree and mildly reduced graphene oxide via solid-state microwave irradiation

Synthesis of graphene oxide and reduced graphene oxide by needle platy natural vein graphite