Reaction Of Graphene Oxide Research Articles

Highly hydrophobic silanized melamine foam for facile and uniform assembly of graphene nanoplatelet towards efficient light-to-thermal energy storage

Solar-thermal technology based on phase change materials (PCMs) has received a lot of attention as a cost-effective and practical way to overcome solar energy intermittency. However, weak photothermal conversion ability and complex preparation processes have hindered the practical application of PCMs. In this work, a new approach for facile, uniform, and firm assembly of graphene nanoplatelet (GNP) through the reaction of graphene oxide (GO) with the silanized melamine foam (MF) is introduced. Here, the deposited amino siloxane layer not only promotes the adhesion and integrity of embedded GNP/GO nanosheets but also facilitates the synthetic route compared to the previous studies. Following the reduction of GO with oleylamine (OA), the hybrid GNP/rGO foams with an integrated network were obtained. The composite PCMs were prepared through the incorporation of paraffin wax (PW) into the hybrid structure. The high hydrophobicity and porosity of the GNP/rGO foams resulted in a high loading of paraffin wax (nearly 97 wt%) and thus large transition enthalpy of 182 J g-1. The GNP/rGO framework provided excellent solar-thermal storage efficiency of up to 92.2%. The PCM composite containing the highest content of GNP (6 wt%) revealed an enhanced thermal conductivity by 87% compared to the unmodified MF/PW composite.

Effect of Durian Peel Ash Added in Zinc Oxide/Reduced Graphene Oxide Composites Used as a Chemical Sensor for Hydrazine Detection

As the hydrazine is toxic, the methods to detect hydrazine at low concentrations are essential in scientific research. This preliminary study reported on how to increase the efficiency of ZnO/reduced graphene oxide (rGO) by adding durian peel ash (DPA) and using three-electrode method. The ZnO/rGO composites were prepared using chemical reaction of graphene oxide (GO) with zinc chloride. The rGO was prepared by the chemical reduction of GO using hydrazine. The properties of the samples were investigated using scanning electron microscopy, atomic force microscopy, X-ray diffraction, and Potentiostat/Galvanostat. The results showed that the optimal condition for the composite material was 70%DPA:30%ZnO/rGO with the sensitivity of 222.92 mA/mM·cm2 and the current density up to 116.50 ± 0.95 A/g. The relationship between the current and the hydrazine concentration was I (μA) = 48.69 + 21.91C (mM) with R2 of 0.9870. The minimum concentration of hydrazine solution that the modified electrode can measure was 0.125 mM. The DPA powder can then be used to enhance the hydrazine detection efficiency at low concentrations.

Improving the performance of water-based drilling fluid using amino acid-modified graphene oxide nanocomposite as a promising additive

It is possible to take advantage of nanomaterials' properties to improve water-based drilling fluids' flux and physical properties. In this paper, glycine methyl ester hydrochloride was synthesized, and the chemical structure was verified to be used as a surface modifier of graphene oxide. At the same time, graphene oxide was prepared from graphite and chlorinated with thionyl chloride, and a nucleophilic substitution reaction was performed to increase the hydrophilicity of graphene oxide. FTIR, Raman, HRTEM, and XRD techniques have identified the prepared and obtained materials from chlorinated graphene oxide's reaction with glycine methyl ester hydrochloride. The glycine-modified graphene oxide (GO) was evaluated as drilling-fluid additives at different concentrations (2.66%, 5.32%, and 10.64%) to enhancement the thermal stability of water-based drilling fluid and reducing the filtration loss. The obtained results confirmed that the successful glycine-modified graphene oxide/bentonite to enhance both thermal stability (up to 350 °F) and filtration loss.

Selective CO2 adsorption and H2 storage in two porous amine-pillared graphene oxide frameworks

Two porous graphene oxide frameworks (GOFs) have been synthesized by a reaction of graphene oxide (GO) and benzylamine (GOF-1) or p-xylylenediamine (GOF-2) through a solvothermal process. The structures and porosity of these two GOFs were characterized and they exhibited different adsorption behaviours. GOFs both showed enhanced porosity and surface area than the parent graphene oxide, which was ascribed to the tunable interlayer spacing. The GOFs possess good H2 storage capacity (0.46 wt% for GOF-1 and 0.57 wt% for GOF-2 at 77 K and 1 bar) though with rather small surface area (86.4 m2/g for GOF-1 and 102.7 m2/g for GOF-2). The CO2 adsorption capacity and selectivity over N2 of GOFs has also been investigated by ideal adsorbed solution theory (IAST) method, and GOF-2 exhibited CO2/N2 selectivity of 40.7 which was higher than that of GOF-1. It emphasized a tunable synthesis of multifunctional materials for H2 storage and CO2 separation from flue gases by decorating 2-dimensional GO nanosheets.

Free chlorine induced phototransformation of graphene oxide in water: Reaction kinetics and product characterization

Herein, the reaction of graphene oxide (GO) in the presence of free chlorine, exploring a variety of water chemistries, is described under both dark and ultraviolet (UV) irradiated conditions. For all conditions evaluated, GO reacts with free chlorine and the reaction rates are considerably enhanced under UV irradiation. Relative reaction kinetics are observed to be pseudo second order overall, while being first order to GO and pseudo first order to initial chlorine concentration. In addition to UV light irradiation, relative rate constants and reaction extents are affected by pH, dissolved oxygen, and the size of initial GO coupon itself. Advanced product characterizations using UV–vis spectroscopy, TEM, FTIR, TOC, Raman spectroscopy, mass spectrometry (MALDI), and XPS indicate GO is significantly transformed, being further oxidized – including significant mineralization to CO2 in some cases. Further, a fraction of the product(s) is identified to eventually stop reacting with free chlorine, suggesting a final, relatively recalcitrant portion of products. For all reactions, carbon mass conservation between the gas (as CO2) and liquid (as GO products) phases is established. Observed reactivity has direct implications for GO life cycle assessments and for material performance in water treatment technologies, such as membrane and disinfection processes, which utilize chlorine and/or UV irradiation, in addition to other GO based technologies.

Surface functionalization of graphene oxide with DBU as electrode materials for supercapacitors

Nitrogen-containing groups functionalized graphene has been synthesized via the reaction of graphene oxide with 1, 8-diazoicyclo (5, 4, 0) undecene-7, trimethylamine (DBU) through epoxide-ring-open reaction without high temperatures. Samples were analyzed by x-ray diffraction spectroscopy, Raman, N2 adsorption-desorption, transmission electron microscope, galvanostatic charge/discharge, and cyclic voltammetrys. Results show that the amount of added DBU has great influence on the structure and properties of the resultant graphene. The DBU modified graphene with appropriate N content and low charge transfer resistance exhibits 190 F g−1 at 5 mV s−1 in 6 M KOH aqueous solution. This will also provide a new strategy for configuring nitrogen-containing groups functionalized graphene electrode materials for supercapacitors and other energy storage devices.

Nanocrystalline Cellulose-Functionalized Reduced Graphene Oxide Nanosheets and Their Composite Papers.

Aqueous-dispersed nanocrystalline cellulose functionalized-reduced graphene oxide (NCC-RGO) nanosheets (the precursor of the composite papers) were prepared via the reaction of graphene oxide (GO) nanosheets, NCC, and ascorbic acid. In this reaction, stiff rod-like NCC was attached to the surface of GO nanosheets via hydrogen bond interactions, which prevented the agglomeration of the nanosheets as the surface oxygen-containing functional groups were removed by ascorbic acid The NCC-RGO composite papers were fabricated using a flow-induced self-assembly strategy with vacuum filtration. NCC-RGO nanosheets underwent layer-by-layer self-assembly on the filter membrane as water permeated the membrane. The structures as well as the electrical and mechanical properties of the NCC-RGO nanosheets and the NCC-RGO composite papers were investigated. The results revealed that the aqueous dispersions of the NCC-RGO nanosheets exhibited long-term stability, consequently producing well-aligned, robust, electrically conductive NCC-RGO composite papers.

A Study of a Novel Nanocomposite Material Based on Reduced Graphene Oxide and Poly(o-Phenylenediamine)

The formation of a nanocomposite coating based on reduced graphene oxide (RGO) and poly(o-phenylenediamine) (PPD) in the chemical reaction of graphene oxide (GO) and o-phenylenediamine (OPD) has been studied by cyclic voltammetry (CVA), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). It has been shown that the action of cyclic polarization provides a more uniform structure of the nanocomposite films (decrease in the corrugation effect). In addition, it has been found that the polarization of GO films containing the OPD monomer distributed inside to the PPD synthesis potentials leads to the formation of uniformly distributed globular structures, which most probably correspond to a polymer electrochemically synthesized in the space between the GO nanosheets.

Fully scalable one-pot method for the production of phosphonic graphene derivatives.

Graphene oxide was functionalized with simultaneous reduction to produce phosphonated reduced graphene oxide in a novel, fully scalable, one-pot method. The phosphonic derivative of graphene was obtained through the reaction of graphene oxide with phosphorus trichloride in water. The newly synthesized reduced graphene oxide derivative was fully characterized by using spectroscopic methods along with thermal analysis. The morphology of the samples was examined by electron microscopy. The electrical studies revealed that the functionalized graphene derivative behaves in a way similar to chemically or thermally reduced graphene oxide, with an activation energy of 0.014 eV.

Effect of microwave power on created defects in graphene sheet of synthesized TiO2/graphene nanocomposite with enhanced photocatalytic performance

Nanocomposites of titanium dioxide and reduced graphene oxide (RGO), was prepared with a fast and simple microwave irradiation method by the reaction of graphene-oxide and commercial TiO2 nanoparticles in water/ethanol solvent. In a comparative study we examined different microwave powers 270W, 450W, 720W, and 900W with different time intervals for each case to find the effect of time and power on absorption wavelength and the creation of defects in graphene layer systematically. We found an optimum irradiation time in which the nanocomposite has the highest absorption wavelength (the smallest band gap), and the optimum value for microwave power in which the nanocomposite has the lowest amount of defect. First, graphite-oxide was prepared using modified Hummer's method and then we used TiO2 and the mixture of water/ethanol and graphene-oxide (GO), for hydrolysis of TiO2 followed by its mounting on graphene-oxide. We used microwave irradiation to produce TiO2/RGO nanocomposite in a way that microwave irradiation reduced graphene-oxide to graphene and created TiO2/RGO nanocomposite. Also we showed TiO2/RGO has a higher photocatalytic activity compared to pure TiO2. Characterization has been done by X-ray diffraction, ultraviolet-visible spectroscopy, transmission electron microscopy, scanning electron microscopy, Raman and Fourier transform infrared spectroscopy to support our results.

Large scale production of graphene quantum dots through the reaction of graphene oxide with sodium hypochlorite

A facile method to produce graphene quantum dots on a large scale was introduced with the usage of oxygen radicals under UV irradiation.

Preparation and characterization of functionalized graphite/poly(butylene terephthalate) composites

Poly(butylene terephthalate)/graphite (PBT/GP) composites were prepared using a melt-mixing method. To enhance the compatibility between PBT and GP, acrylic acid-grafted PBT (PBT-g-AA) and multi-hydroxyl-functionalized graphene oxide (GO-OH) were used to replace PBT and GP, respectively. Composites of PBT/GP or PBT-g-AA/GO-OH were prepared with 0, 1, 3, and 5 wt% inorganic filler (GP or GO-OH) contents. Crude graphene oxide (GO) was oxidized chemically using a mixture of H2SO4 and HNO3 and then reacted with thionyl chloride to functionalize it with chlorocarbonyl groups (GO-COCl). GO-OH was obtained from the reaction of graphene oxide (GO)-COCl with ethylene glycol. The composites were characterized morphologically by transmission electron microscopy. The PBT-g-AA/GO-OH was also characterized by FTIR spectra, 13C solid-state NMR spectra, UV–Vis spectra, TEM micrographs, DSC analysis, TGA analysis and Electrical conductivity. The PBT-g-AA/GO-OH (3 wt%) composites had significantly improved thermal properties. The functionalized PBT-g-AA/GO-OH composite showed markedly enhanced anti-static properties. The optimal proportion of GO-OH in the composites was 3 wt%. In excess of this amount, the compatibility between the organic and inorganic phases was compromised.

Functionalization of graphene using trimethoxysilanes and its reinforcement on polypropylene nanocomposites

Functionalized reduced graphene oxide (RGO) was obtained by reaction of graphene oxide with dodecyl (12C), octyl (8C) and propyl (3C) trimethoxysilane and subsequent reduction using hydrazine hydrate. The results showed the successful grafting of the alkyl groups onto the surface of RGO, and that the longer alkylated chains made graphene more lipophilic. Furthermore, the RGO-12C was incorporated into polypropylene matrix as a reinforcing component by solution mixing. The resulting nanocomposites displayed a significant improvement in thermal stability, crystallinity and mechanical properties. This work suggests a new route to improve the solubility and dispersion of graphene in polymer matrix.

Square wave anodic stripping voltammetry determination of lead based on the Hg(II) immobilized graphene oxide composite film as an enhanced sensing platform

In present paper, Hg(II) modified graphene oxide (Hg(II)/GO) was firstly prepared by reaction of graphene oxide (GO) with Hg(II). The Hg(II)/GO dispersed in a Nafion solution was coated on the polished glassy carbon electrode (GCE) for fabricating the enhanced electrochemical sensing platform. And then Hg(II)/GO modified GCE was held at a negative potential (−1.0V) to reduce the coordinated Hg(II) to Hg forming Hg nanodroplets, which was been used as the sensing platform to determine Pb2+ by square wave anodic stripping voltammetry (SWASV). In comparison with the Hg(II) immobilized MWCNT graphite electrode, the response signal of our electrode was obviously increased owing to the unique structure of GO. The linear calibration curves ranged from 5ngL−1 to 70ngL−1 and 0.1μgL−1 to 10μgL−1 for Pb2+. The detection limit (S/N=3) was estimated to be around 0.13ngL−1 for Pb2+. The practical application of Hg(II)/GO modified GCE was also evaluated by the detection of Pb2+ in different water samples, the results suggest that the sensor is very promising for practical applications.

Preparation and Properties of Luminescent Lanthanide Based Graphene Oxide

Novel photoluminescent materials were prepared from the reaction of graphene oxide and luminescent lanthanides (europium, terbium, gadolinium, samarium, and dysprosium) in methanol at high pH. The binding of the lanthanides to graphene oxide through the oxygen functionality was evidenced by the sharp enhancement of laser induced luminescence and the appearance of peaks in specific regions of the spectra of the lanthanides. Raman spectroscopy indicated that the graphene oxide maintained its structure within the material and verified the complexation with the lanthanide. Surface morphology studies using SEM and TEM demonstrated the coverage of the graphene oxide surface by the lanthanide. Although some limited work has been published on europium and graphene oxide, this is the first study encompassing the majority of the luminescent lanthanides, taking full advantage of their capabilities including advanced electronic structure, raman and visible luminescence in a variety of colors.

Effects of covalent surface modifications on the electrical and electrochemical properties of graphene using sodium 4-aminoazobenzene-4′-sulfonate

The broad application of graphene is impeded by its intrinsically insoluble property. Therefore, two types of water dispersible graphene were synthesized by the reaction of graphene oxide (GO) with sodium 4-aminoazobenzene-4′-sulfonate (SAS) and its aryl diazonium salt (ADS). The maximum dispersibilities of SAS- and ADS-functionalized graphene (SAS-G and ADS-G) in water were 1.4 and 2.9mgmL−1, respectively. Fourier transform infrared, Raman and X-ray photoelectron spectroscopy (XPS) revealed successful surface modification of graphene using SAS and ADS. The electrical conductivity of ADS-G (1120Sm−1) was much greater than SAS-G (149Sm−1), which is attributed to two-step reduction of GO to graphene. Thermogravimetric analysis revealed that excess surface modifier was attached to the surface of the ADS-G compared to SAS-G, which corroborates the Raman and XPS analysis. The electrochemical properties of the formed SAS-G and ADS-G were investigated, and the results demonstrated that ADS-G showed better specific capacitance (210Fg−1) than SAS-G (170Fg−1). All these observations confirmed that the surface modified graphene can be used as energy storage electrode materials because of their high specific capacitance values.