Chemical Reduction Of Graphene Oxide Research Articles

Magnetic polyethyleneimine functionalized reduced graphene oxide as a novel magnetic sorbent for the separation of polar non-steroidal anti-inflammatory drugs in waters

A novel magnetic polyethyleneimine modified reduced graphene oxide (Fe3O4@PEI-RGO) had been prepared and then was successfully employed to extract three polar non-steroidal anti-inflammatory drugs (NSAIDs) in different water matrices for the first time coupled with high performance liquid chromatography-diode array detector (HPLC-DAD). The magnetic polyethyleneimine (Fe3O4@PEI) composite was first synthesized via one-pot hydrothermal approach and then the Fe3O4@PEI-RGO composite was fabricated on the basis of a simple self-assemble approach between positive charged Fe3O4@PEI and negative charged GO sheets via electrostatic interaction followed by chemical reduction of GO to RGO. The as-prepared Fe3O4@PEI-RGO composite was carefully characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), thermal gravimetric analyzer (TGA), vibrating sample magnetometer (VSM) and zeta potential analysis. As a surface modifier of RGO, PEI not just changed the polarity of RGO to some extent but also offered more adsorption sites to polar NSAIDs. Compared with Fe3O4@PEI, Fe3O4-RGO and Fe3O4@PEI-GO, the as-prepared Fe3O4@PEI-RGO composite, which combined the advantage of PEI and RGO, showed higher extraction efficiency for polar NSAIDs. In addition, the adsorption mechanism was also studied. The analytical parameters influencing the extraction efficiency were optimized in detail. A satisfactory performance was obtained under the optimal conditions. The calibration lines were linear over the concentration in the range of 1–800 μg L−1 for all the analytes with determination coefficients (r2) varying from 0.9972 to 0.9986. The limits of detection (LODs) were 0.2 μg L−1. The recoveries were between 91.20% and 101.13% with relative standard deviations (RSDs) in the range of 1.09–7.34%. Overall, a fast, convenient, sensitive and eco-friendly method was successfully proposed and became a promising approach for the determination of trace polar NSAIDs in complex matrices.

Graphene a promising electrode material for supercapacitors-A review

The global demand for high performance and environmentally friendly energy storage systems leads to intensive research on new and advanced electrode materials that are able to satisfy the fast-growing global market in various applications. The 2D graphene material is one of the most promising candidates for next-generation energy storage applications, particularly supercapacitor devices due to its exceptional intrinsic properties such as highest theoretical specific surface area (2600 m2/g), high electrical charges mobility (230 000 cm2/V·s), thermal conductivity (3000 W/mK), and highest strength (130 GPa). This comprehensive review summarizes the most recent progress made on the graphene material in its different structural forms of foams (3D), thin films (2D), nano-fibers (1D), and nano-dotes (0D) for supercapacitor electrodes. It initiates with a brief historical introduction on graphene discovery and its current production techniques that retain its intrinsic properties ranging from mechanical exfoliation of graphene in high quality to its epitaxial growth by chemical vapor deposition on metal substrates and its derivation by chemical reduction of graphene oxide. In addition to highlighting its main characterization techniques such as Raman spectroscopy, atomic force microscopy, and transmission electron microscopy, as well as, its critical properties including electrical, optical, mechanical, and thermal properties. Its potential applications are also illustrated with emphasizing on its usage as an electrode material in supercapacitors. Finally, its main challenges and future prospects are considerably pointed out.

In situ one pot synthesis of nanoscale TiO2-anchored reduced graphene oxide (RGO) for improved photodegradation of 5-fluorouracil drug

This paper reports an ‘in situ’ precipitation-reduction reaction for the scalable production of nanoscale TiO2-anchored reduced graphene oxide (RGO–TiO2) nanocomposites. RGO–TiO2 nanocomposites with different weight ratios were prepared by the simultaneous hydrolysis of titanium tetraisopropoxide (TTIP) and the chemical reduction of graphene oxide. The as-prepared samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, Ultraviolet–Visible diffused reflectance spectroscopy, and photoluminescence. The most commonly used cytostatic (antineoplastic) drug in cancer therapies [5-fluorouracil (5-FU)] was used as a model pollutant. To examine the effects of RGO, the photocatalytic degradation of 5-FU was examined by varying the operational parameters, such as catalyst amounts, solution pH, effect of scavenger, and TiO2 mass contents. Under the optimal experimental conditions, 97% of the 5-FU present was photodegraded over RGO–TiO2 (RGO–T2) within 90 min under UV light. The RGO–TiO2 composites (RGO–T2) exhibited two times higher photocatalytic activity than that of pure TiO2. The improved photocatalytic activities of the RGO–TiO2 nanocomposites were attributed to the homogeneous distribution of TiO2 nanoparticles over the surface of the RGO nanosheet, enhancement of the light absorption intensity, and suppressed recombination of photoinduced electron–hole pairs.

Comparative study on chemical reduction of free-standing flexible GO films and their cyclic voltammetry performance

Chemical reduction of graphene oxide (GO) is one of the most practical methods to recover the properties of graphene. However, these properties vary with the reduction agents. Understanding these differences is fundamental to applications related to reduced graphene oxide (RGO). In this work, six different reduction agents were used to make flexible and free-standing RGO films, resulting in different properties such as surface morphology, inner structure, surface C/O ratio, electrical conductivity, and wettability. We found that not all the six reduction agents were suitable for making flexible and free-standing films. Then, we further studied the electrochemical behavior of these samples and found that the electrochemical properties of the RGO films depend on all the properties but electrical conductivity played the most important role in determining the pseudocapacitance behavior.

Preparation of Monodispersed Carbon Spheres via Hydrothermal Carbonization of Ascorbic Acid and Their Application in Lithium Ion Batteries

Hydrothermal carbonization is one of the most appealing strategies to prepare carbon spheres(CSs). Nevertheless, the precursors of hydrothermal carbonization are limited to several saccharides currently and the obtained CSs are easily interconnected among each other, giving rise to difficulties in further treatment and applications. In this work, ascorbic acid was used as precursor in the hydrothermal procedure and monodispersed CSs could be fabricated without any catalysts. In addition, the composites of CSs and chemical reduced graphene oxide(CRG) possessing three dimensional network structures were fabricated, which exhibited excellent electrochemical performance used as anode in lithium ion battery(LIB). Meanwhile, the effects of size distributions of CSs on the electrochemical performances were evaluated.

Bio-inspired AgNPs, multilayers-reduced graphene oxide and graphite nanocomposite for electrochemical $$\hbox {H}_{2}{\hbox {O}}_{2}$$ H 2 O 2 sensing

A bio-mediated route for the synthesis of silver nanoparticles (AgNPs) is an area of interest in research of many scientists, and this work aims to study the electrocatalytic activity of these particles during electrochemical sensing of H\(_{2}\)O\(_{2 }\) in a phosphate buffer media. The composite electrodes were fabricated using nearly spherical AgNPs and reduced graphene oxide (rGO) with the graphite (99.999% purity) support made of graphite paste. Graphene oxide (GO) was first synthesized using the modified Hummers method followed by rGO synthesis by chemical reduction of GO. rGO is consisting of about nine layers of rGO sheets of a wrinkled surface morphology with an intensity ratio of D to G band (\(I_{D}/I_{G})\) of 1.17 and an interplanar d-spacing of 0.36 nm as evidenced by HRTEM micrograph. There was about 10 times increase in the cell current with the AgNPs-impregnated composite–electrode compared to without AgNPs impregnation, and an overpotential of \(\hbox {H}_{2}\hbox {O}_{2}\) reduction was found to be \(-\)1.373 V with a detection limit of 19.04 \(\upmu \)M and 95.3% electrode stability with the graphite–rGO–AgNPs composite electrode. A nafion membrane cast on the rGO–AgNPs prevented the leakage of this composite from the electrode surface. The interference of various electroactive compounds on the amperometric response of the graphite–rGO–AgNPs electrode was also investigated.

Reduced Graphene Oxide Joins Graphene Oxide To Teach Undergraduate Students Core Chemistry and Nanotechnology Concepts

Novel carbon nanomaterials such as reduced graphene oxide (rGO) and graphene oxide (GO) can be easily incorporated into the undergraduate curriculum to discuss basic chemistry and nanotechnology concepts. This paper describes a laboratory experiment designed to study the differences between GO and rGO regarding their physicochemical properties (e.g., color, hydrophobicity, type of functional groups, electrical conductivity, etc.). In this course, students carry out the chemical reduction of GO using ascorbic acid, a mild and environmentally friendly reducing agent. The differences between GO and rGO can be spotted by the naked eye and can be further evaluated by spectroscopic methods, as Fourier transform infrared and UV–vis spectroscopy and X-ray diffraction. Simple and applicable in all laboratories, use of the multimeter to measure resistance was proposed to reveal the different electrical properties of GO and rGO. Moreover, the proposed laboratory experiment is an ideal pretext to discuss the definiti...

A ternary nanocomposite of reduced graphene oxide, Ag nanoparticle and Polythiophene used for supercapacitors

ABSTRACTThe ternary nanocomposites of reduced graphene oxide (rGO), Ag nanoparticles, and polythiophene (PTh), (rGO/Ag/PTh) with different initial feed ratios of [GO]o/[Th]o = 0.2, 0.3 and 0.4 were used in a symmetric supercapacitor device formation. rGO/Ag/PTh nanocomposite has been prepared by in-situ polymerization and chemical reduction of graphene oxide. Fourier transform infrared spectroscopy –Attenuated total reflectance (FTIR-ATR) and scanning electron microscopy (SEM) were employed in order to characterize the composition of the resulting nanocomposites and morphology. The electrochemical behavior of these nanocomposites were studied by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopic (EIS) measurements in 1.0 M H2SO4 solution. As an electroactive material, rGO/Ag/PTh nanocomposite shows good capacitive performance in acidic electrolyte solution, a high specific capacitance (up to Csp = 953.13 F/g at a scan rate of 4 mV/s) at [GO]o/[Th]o = 0.2. Moreover, the rGO/Ag/PTh nanocomposites at [GO]o/[Th]o = 0.2 show high stability with 91.88% specific capacitance saved after 1000 charge/discharge processes. Furthermore, larger energy density (up to E = 28.8 Wh/kg at a scan rate of 5 mV/s and a power density of P = 2843.3 W/kg at a scan rate of 1000 mV/s) of the nanocomposites at [GO]o/[Th]o = 0.2 is obtained in 1 M H2SO4 aqueous electrolyte for two-electrode device formation. This study has revealed that the rGO/Ag/PTh nanocomposite electrode materials may lead to a stable supercapacitor for portable electronic applications.GRAPHICAL ABSTRACT

Simultaneous Surface Modification and Chemical Reduction of Graphene Oxide Using Glucose.

In this paper, we develop a simple and facile approach to prepare graphene nanosheets through chemical reduction with glucose as reducing agent and modification agent. The reduced and modified graphene by glucose (denoted as g-rGO) was characterized with techniques of Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Raman spectra, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), etc. It is found that, besides the desired reduction capability to graphene oxide (denoted as GO), glucose plays an important role as a modifying reagent in stabilizing the as-prepared graphene nanosheets simultaneously and the g-rGO exhibits good dispersibility and stability in water and waterborne polyurethane matrix (denoted as WPU). Moreover, the g-rGO can improve evidently the mechanical properties, weather ability and water resistance of WPU.

Nanoscale friction of graphene oxide over glass-fibre and polystyrene

Coatings of graphene oxide over two substrates of glass-fibre and polystyrene were obtained by electrophoretic deposition (EPD). A chemical reduction of graphene oxide by exposure to hydrazine hydrate at 100 °C significantly changes the interfacial interaction with the substrate as well as the tribology. Spectroscopic techniques like Fourier transform infrared, Raman spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction showed that the treatment with hydrazine replaces oxygen functional groups and also induces roughness, a structural disorder and decreases the interlayer separation in the transition from graphene oxide (GO) to reduced graphene oxide (rGO). Treatment with hydrazine reduces adhesion and friction force against diamond like carbon coated Si probe (DLC AFM) at the basal plain of the coatings. Investigation at the edges revealed that the presence of oxygenic functional groups leads to higher shear strength with glass-fibre and polystyrene which reduces after treatment with hydrazine.

Low content Ag-coated poly(acrylonitrile) microspheres and graphene for enhanced microwave absorption performance epoxy composites

Silver nanoparticles was uniformly anchored on the surface of hollow poly(acrylonitrile) microspheres with a facile chemical method using hydrazine hydrate as reductant. Integrating these conducting hollow spheres (PANS@Ag) with chemical reduced graphene oxide (RGO) dispersed in epoxy resin, a lightweight microwave absorber was successfully prepared with enhanced microwave absorption performance. The chemical constitution and surface morphology of as-synthesized RGO and PANS@Ag powders were characterized by XRD, XPS, FE-SEM and SAED, while the electromagnetic properties of these different proportion PANS@Ag-RGO/EP samples were analyzed through vector network analyzer (VNA). The minimum reflection loss (RL) could reach up to −28.1 dB at 8.8 GHz with a layer thickness of 2 mm, and the corresponding effective absorption bandwidth (RL values less than −10 dB) was from 7.9 GHz to 9.8 GHz. However, the dosage of PANS@Ag and RGO was merely 3 wt% and 1 wt%, respectively. As the content of PANS@Ag powders decreased to 1 wt%, the PANS@Ag-RGO/EP samples still retained effective microwave absorption performance and the optimal RL was −14.7 dB. The density of as-prepared absorbers was in the range of 0.49 ∼ 0.87 g cm−3. The low content, low density and enhanced microwave absorption performance endow the hybrid composites with competitive application prospect in stealth technology field.

Study on the effect of graphene and glycerol plasticizer on the properties of chitosan-graphene nanocomposites via in situ green chemical reduction of graphene oxide

Unplasticized and glycerol plasticized chitosan/graphene (CS/GS) nanocomposites were synthesized via in situ chemical reduction of graphene oxide sheets (GO) with l-ascorbic acid (L-AA) as reductant by solution casting. The reduction of GO with L-AA was investigated to establish the optimal amount of reductant required to produce chemically reduced graphene sheets (GS). The combine effect of both nanofiller and glycerol on the structure, thermal, mechanical, and electrical properties of CS/GS nanocomposite films was evaluated. Materials were characterized by FT-IR, NMR, UV–Vis, XPS, XRD, Raman, SEM, TEM, and TGA. The results showed that GS sheets were homogeneously dispersed throughout the CS matrix, and that interactions between CS and the surface of GS took place. When compared with neat CS, nanocomposites showed a decrease in the crystallinity, better thermal stability under oxidative atmosphere, and improved mechanical properties, while maintained the thermal properties of CS under inert conditions. Combined use of glycerol and GS led to substantially enhanced mechanical properties. The electrical conductivity was increased with increasing GS loading in nanocomposite. This study demonstrates how CS/GS nanocomposites performance properties can be tailored by controlling GsS and plasticizer content.

Ultrasound assisted catalytic degradation of textile dye under the presence of reduced Graphene Oxide enveloped Copper Phthalocyanine nanotube

In this work, ultrasound assisted catalytic removal of Rhodamine B (RhB) dye has been carried out in the presence of reduced Graphene Oxide enveloped Copper Phthalocyanine nanotube (RGO-CuPc) for the first time. This RGO-CuPc nanocomposite has been synthesized by in situ chemical reduction of Graphene Oxide (GO) with CuPc tube. Then our as prepared composite and pristine CuPc tubes are well characterized by various spectroscopic techniques such as X-Ray Diffraction, UV–vis and microscopic techniques like FESEM, HRTEM etc. Electrochemical EIS measurement has also been carried out to investigate charge transfer mechanism. These results confirm the purity of the as prepared samples. Efficient sonocatalytic RhB dye removal upto ∼92.22% is achieved by RGO-CuPc composite within 100 min as compared to pristine CuPc tube (∼70%). A plausible reaction pathway towards dye removal is discussed in detail. Also degradation performance in the presence of enhancer and scavenger has been investigated.

Development of a third generation biosensor to determine hydrogen peroxide based on a composite of soybean peroxidase/chemically reduced graphene oxide deposited on glassy carbon electrodes

A third generation enzymatic biosensor is developed to determine H2O2. The biosensor is based on the use of a composite obtained from soybean peroxidase enzyme and chemically reduced graphene oxide deposited at glassy carbon electrodes. Experiments were carried out in 0.1 M phosphate buffer solutions, pH 7.0.Cyclic voltammograms of the biosensor show two reduction peaks centered at about 0.15 and −0.4 V, respectively. A quasi-reversible redox couple is defined in the region of potentials of the first peak, which is assigned to the reduction/oxidation of compound II involved in the catalytic cycle of peroxidases. The surface concentration of the electroactive enzyme was (1.1 ± 0.2) × 10−10 mol cm−2. Values of 0.33 and 0.04 s−1 were determined for the cathodic charge transfer coefficient and the heterogeneous electron transfer rate constant, respectively. UV–vis spectroscopy and scanning electron microscopy (SEM) were used to demonstrate the chemical reduction of graphene oxide. Electrochemical impedance spectroscopy was used to characterize the different stages in the process of the electrode surface modification.Amperometric measurements were performed at a potential of −0.090 V vs. Ag/AgCl. Current responses were linear in the concentration range from 1.5 × 10−7 to 3.0 × 10−6 M. The limit of detection, limit of quantification, reproducibility, and repeatability were 5 × 10−8 M, 1.5 × 10−7 M, 9%, and 4%, respectively. The biosensor was stable during five days. The Michaelis Menten apparent constant was 1.6 × 10−6 M. The presence of uric acid, glucose, dopamine and ascorbic acid do not interfere in the determination of H2O2.The biosensor was applied to the determination of H2O2 in commercial contact lens care solutions. Good accuracy and recovery parameters were obtained.

Robust Nanowrapping of Reduced Graphene Oxide by Metal-Organic Network Films between Fe Ions and Tetra(Catechol-Substituted) Porphyrin.

We found the utilization of porphyrin-based metal-organic network films composed of tetra(catechol-substituted)porphyrin (cPor) and Fe ions for robust wrapping materials of graphene oxide (GO), which can keep the dispersion state under the chemical reduction of GO to reduced graphene oxide (rGO) in water. The tetra(catechol-substituted)porphyrin (cPor) was designed for soft-wrapping methods because the aromatic porphyrin moieties can be strongly adsorbed onto the surface of GO or rGO via both π-π interactions and the catechol-Fe coordination network formation. The GO sheets covered with the cPor-Fe films were reduced chemically in water under retention of the wrapped nanostructure of the cPor-Fe/GO sheets. The obtained rGO composites after chemical reduction are characterized by using UV-vis absorption, Raman, and X-ray photoelectron spectroscopy (XPS) spectra, as well as thermogravimetric analysis and energy-dispersive X-ray spectroscopy (EDX). XPS and EDX spectra showed the presence of Fe species, which originates from the coordinated Fe-catechol nodes in the wrapped cPor-Fe films. The wrapped rGO sheets could be easily handled in water because of their high solubility therein and exhibits electric conductivity. In dynamic light scattering analysis, the average diameter of rGO composites before and after reduction changed slightly from 419 ± 309 to 663 ± 697 nm, indicating that the chemical reduction is not significantly influenced by the size of the rGO composite or the solubility. It is expected that the soft wrapping cPor-Fe/rGO should employ the applications to prepare functional materials such as modified electrodes, catalysts, energy-storage materials, and electronic devices.

Facile synthesis of graphene via reduction of graphene oxide by artemisinin in ethanol

The preparation of reduced graphene oxide (RGO) by chemical reduction of graphene oxide (GO) usually involves highly toxic reducing agents which are harmful to the environment and human health. In this paper, a mediated facile and relative green approach for the preparation of RGO in ethanol using artemisinin as a reducing agent is reported for the first time. The morphology and de-oxidation efficiency of the obtained RGO were characterized by transmission electron microscope (TEM), atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS). The results showed that artemisinin can effectively reduce GO into few-layered RGO with a high carbon to oxygen ratio (11.7). The mechanism for elimination of oxygen-containing functional groups decorated on GO nanosheets by artemisinin was proposed. The important features of relatively environmentally friendly and facile operation procedures endow this approach with great promise in the mass production of RGO and various graphene-based materials, especially for biomaterials.

Preparation of Pt/G and PtNi/G nanocatalysts with high electrocatalytic activity for borohydride oxidation and investigation of different operation condition on the performance of direct borohydride-hydrogen peroxide fuel cell

In this work, graphene supported Pt (Pt/G) and NiPt nanoparticles (NiPt/G) were synthesized by in situ chemical reduction of graphene oxide, Ni+2 and Pt+4 ions. The structural investigation was performed by Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS), Brunauer, Emmett, and Teller (BET) analysis, Field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The electrocatalytic activity of the Pt/G and PtNi/G catalysts toward BH4− oxidation in alkaline media was investigated by means of cyclic voltammetry (CV) and chronoamperometry (CA). The results showed that the catalytic activity of the PtNi/G catalyst toward NaBH4 electrooxidation was higher than that of Pt/G because of the synergistic effect between Pt and Ni. A direct borohydride-hydrogen peroxide fuel cell (DBHPFC) was fabricated using Pt/G (0.5 mg cm−2) as cathode catalyst and NiPt/G as anode catalyst. The maximum power density was 64.9 mW cm−2 at 60 °C, 1 M NaBH4 and 2 M H2O2 for anodic loading of 2 mg cm−2 and 60.4 mW cm−2 at 60 °C, 1 M NaBH4 and 2 M H2O2 for anodic loading of 1mg cm−2.

Vancomycin-assisted green synthesis of reduced graphene oxide for antimicrobial applications

Chemical reduction of graphene oxide (GO) is a simple and inexpensive method for the large-scale production of graphene-based materials. A suitable reducing agent, especially a green reductant, is in high demand for the production of reduced GO (RGO). Vancomycin, a glycopeptide antibiotic used to treat a variety of Gram-positive bacterial infections, was used to chemically reduce GO at a weak alkaline pH. As far as we know, this is the first report of reduction of GO by a glycopeptide antibiotic. The resulting vancomycin-decorated RGO (RGO-Van) was characterized by UV–visible adsorption and Raman spectroscopies, X-ray diffraction pattern and atomic force microscopy (AFM). The antibacterial effect of the RGO-Van suspension was investigated by the bacterial growth curves. The RGO-Van sheet can be fabricated into paper-like film through vacuum filtration. The antibacterial property of the as-obtained RGO-Van film was assessed by the inhibition zone test, and the bacterial adhesion assay. The antibacterial efficacy of the RGO-Van film was also verified by treatment of wound infection caused by Staphylococcus aureus (S. aureus) in a rat infection model.

Smart cellulose/graphene composites fabricated byin situchemical reduction of graphene oxide for multiple sensing applications

Multifunctional sensing abilities of cellulose/in situreduced graphene oxide composites prepared by a simple and “green” approach are presented.

Room temperature ferromagnetism in Graphene-ZnO nanocomposite

Graphene-ZnO nanocomposite has been successfully prepared by chemical reduction of graphene oxide and zinc acetate complex.The nanocomposite was characterized by Powder XRD, FT-IR, HRSEM, PL and VSM technique. The crystalline structure and phase identification of Graphene-ZnO nanocomposite was confirmed by XRD studies. Spherical ZnO nanoparticles anchored on graphene sheets were found in HRSEM. Defects like oxygen vacancy and zinc interstitials present in the samples was confirmed by PL spectra. The magnetization behavior of the samples may be explained on the basis of oxygen vacancy and defect present in the samplesusing VSM studies.During the wrapping of graphene sheets around ZnO, p-orbital of carbon may involve in spin–polarized charge transfer with oxygen vacancies in ZnO. The coercivity values of the pure ZnO and Graphene-ZnO nanocomposite are 210,380 Oe respectively. At the same time, magnetization value is decreased in nanocomposites compared with pure ZnO due to minimized oxygen vacancy