scholarly journals ELECTROCHEMICAL DISPERSION OF GRAPHITE IN 58% NITRIC ACID TO PRODUCE MULTILAYER GRAPHENE OXIDE

2021 ◽  
Vol 64 (3) ◽  
pp. 59-65
Author(s):  
Elena V. Yakovleva ◽  
Andrey V. Yakovlev ◽  
Ivan N. Frolov ◽  
Anton S. Mostovoy ◽  
Vitaly N. Tseluikin
Keyword(s):  
Graphene Oxide ◽  
Graphite Powder ◽  
Multilayer Graphene ◽  
X Ray Diffraction ◽  
X Ray ◽  
Graphene Layers ◽  
Intercalated Compounds ◽  
Fold Reduction ◽  
Electrochemical Dispersion ◽  
Oxidized Graphite

Electrochemical oxidation of graphite powder in 58% HNO3 was studied. Samples of oxidized graphite were obtained with a imparting of the amount of electricity 500, 700, 1500 mAh g-1. The character of the galvanostatic dependencies allows to select a region of the formation of intercalated compounds of graphite prior to the accumulation of quantity of electricity of 500 mA h g-1. It was found that when the quantity of electricity of over 700 mA h g-1 the process of electrochemical peroxidation of intercalated graphite begins with the formation of multilayer graphene oxide, as confirmed by comprehensive studies using X-ray diffraction, scanning electron microscopy, FTIR spectroscopy, laser diffraction. The synthesized multilayer graphene oxide is characterized by the presence of a spectrum of oxygen-containing functional groups, mainly hydroxyl, as well as carboxyl, epoxy and alkoxyl. X-ray images show a peak at 2θ = 11.45° which intensity increases for re-oxidized graphite compounds and also indicate the formation of a multilayer graphene oxide with an interlayer distance of 7.8 Å. The synthesized material in aqueous suspensions under the action of ultrasound is dispersed with a 7-11-fold reduction in particle size. Graphene layers remains layered structure but the degree of their deformation increases, and the thickness of the layers decreases with an increase in the imparted amount of electricity. 

Fire retardancy of graphene oxide/wood composite (GOW) prepared by a vacuum-pulse dipping technique

Holzforschung ◽  
2018 ◽  
Vol 72 (5) ◽  
pp. 375-378 ◽  
Author(s):  
Xiaoshuai Han ◽  
Qinqin Zhang ◽  
Yihui Yin ◽  
Junwen Pu
Keyword(s):  
Graphene Oxide ◽  
Self Assembly ◽  
Degree Of Crystallinity ◽  
Multilayer Graphene ◽  
Layer By Layer ◽  
Fire Retardancy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Natural Wood ◽  
Thermal Stability Of

AbstractGraphene oxide/wood (GOW) composite was fabricated by a vacuum-pulse dipping technique, and the resulting composites were characterized by scanning electron microscope (SEM), Raman spectroscopy and thermogravimetric analysis (TGA). As demonstrated, the wood matrix became filled by the dense multilayer graphene oxide (GO) membrane structure, which was formed by the layer-by-layer self-assembly of GO nano-sheets. X-ray diffraction (XRD) revealed that the amorphous GO decreased the composite’s relative degree of crystallinity. Additionally, the filled GO generated improvement in the thermal stability of GOW composites in comparison with that of the natural wood (NW).

SYNTHESIS OF GRAPHENE OXIDE USING MILDLY OXIDIZED GRAPHITE THROUGH ULTRASONIC EXFOLIATION

2016 ◽  
Vol 24 (06) ◽  
pp. 1750087
Author(s):  
YANG HU ◽  
ZHUANG LI ◽  
HONGQIANG LI ◽  
SHAOXIAN SONG ◽  
ALEJANDRO LOPEZ-VALDIVIESO
Keyword(s):  
Graphene Oxide ◽  
Direct Method ◽  
Reaction System ◽  
X Ray Diffraction ◽  
Oxidation Degree ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Oxidized Graphite ◽  
Ultrasonic Homogenizer

This study investigated the preparation of graphene oxide from mildly oxidized graphite through ultrasonic exfoliation. Both the original and produced materials were analyzed by ultraviolet–visible spectrophotometer, X-ray diffraction and atomic force microscopy. The results indicated that the exfoliation yield of graphene oxide was proportional to the input ultrasonic energy. In addition, a two-stage exfoliation phenomenon was observed in the exfoliation of mildly oxidized graphite with both ultrasonic homogenizer and cleaner. It also was found that increasing the content of [[Formula: see text]] in a C–H2SO4–[[Formula: see text]] reaction system was the most simple and direct method to increase the oxidation degree of graphite oxide.

New evidence for supported metals in the reaction of KC8 with metal chlorides

1992 ◽  
Vol 7 (2) ◽  
pp. 418-422 ◽  
Author(s):  
A. Messaoudi ◽  
F. Béguin
Keyword(s):  
Graphite Powder ◽  
Intercalation Compounds ◽  
X Ray Diffraction ◽  
Metal Chlorides ◽  
X Ray ◽  
Graphene Layers ◽  
Graphite Intercalation ◽  
The Matrix ◽  
New Evidence

The evolution of the reaction between the binary graphitide KC8 and CoCl2 dissolved in anhydrous tetrahydrofuran (THF) has been investigated by in situ x-ray diffraction (XRD). During the reaction and whatever the host graphite (powder or HOPG), the first stage graphite intercalation compounds K(THF)2.5C24 and K(THF)1.7C24 are first formed and then transformed into higher stages. Finally the matrix is exfoliated and the phases identified are graphite, metallic cobalt, and KCl. Analyses by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) clearly show that the products are mainly located at the edge planes of the graphite, indicating that the electronic exchange occurs at the edge of the graphene layers. It is now clear that graphite-cobalt intercalation compounds cannot be obtained by this method.

X-Ray Diffraction Evaluation of the Average Number of Layers in Thermal Reduced Graphene Powder for Supercapacitor Nanomaterial

2019 ◽  
Vol 958 ◽  
pp. 117-122 ◽  
Author(s):  
Quezia de Aguiar Cardoso ◽  
Julio César Serafim Casini ◽  
Luzinete Pereira Barbosa ◽  
Marilene Morelli Serna ◽  
Eguiberto Galego ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Thermal Treatment ◽  
Low Cost ◽  
Reduction Process ◽  
Thermal Reduction ◽  
Processing Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Graphene Layers ◽  
Number Of Layers

Graphene oxide (GO) can be partially reduced to graphene-like sheets by removing the oxygen-containing groups and recovering the conjugated structure. In this work, the thermal reduction of GO powder has been carried out using back pumping vacuum pressures and investigated employing X-ray diffraction analysis. The experimental results of estimating the number of graphene layers on the reduced powder at various temperatures (200 – 1000 °C) have been reported. Electrical changes have been produced in a graphene oxide with the vacuum reduction process. This study has shown that the ideal processing temperature for reducing graphene oxide nanomaterial was about 400 °C. It has also been shown that at 600 °C the number of layers in the reduced nanomaterial increased. The internal series equivalent resistance (ESR) has been improved substantially with the vacuum thermal treatment even at temperatures above 400 °C. ESR was reduced from 95.0 to about 13.8 Ω cm2 with this processing. These results showed that the process can be applied to the reduction of graphene oxide to produce supercapacitor nanomaterials. The advantage of employing this method is that the processing is a straightforward and low cost thermal treatment that might be used for large amount of nanocomposite material.

scholarly journals Performance Enhancement of Modified 3D SWCNT/RVC Electrodes Using Microwave-Irradiated Graphene Oxide

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Ali Aldalbahi ◽  
Mostafizur Rahaman ◽  
Mohammed Almoiqli
Keyword(s):  
Graphene Oxide ◽  
Structural Changes ◽  
Performance Enhancement ◽  
Photoelectron Spectra ◽  
Composite Electrodes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Graphene Layers ◽  
Electrode Surfaces ◽  
Porous Architecture

Abstract The goal of this article is to increase the electrode performance of 3D CNT/RVC electrodes by improving the ease of ion adsorption to and ion desorption from the electrode surfaces. This achievement was done by preparing different composites of synthesized microwave-irradiated graphene oxide (mwGO) with CNT and coated on RVC. The morphology of GO was examined by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) study. Its surface property was checked by energy-dispersive X-ray spectra (EDX), and Fourier transform infrared spectra; whereas, for mwGO by XRD, Raman spectra, and X-ray photoelectron spectra (XPS), which revealed some structural changes of GO after irradiation, where CNTs, being sandwiched between graphene layers, built 3D highly porous architecture inside the electrodes. The electrochemical test of composite electrodes showed increased electrodes conductivity and afforded rapid ions diffusion. It is observed that the 9-CNT/mwGO/RVC composite electrode performed as the best electrode, which showed 29% increment in specific capacitance value compared to the normal CNT/RVC electrode. This best electrode also showed very high cyclic stability in its cyclic voltammetry test that maintained 97% current stability after 2000 cycles, indicating that the electrode can be an effective material for water purification technology. Graphical Abstract

scholarly journals Attached β-cyclodextrin/γ-(2,3-epoxypropoxy) propyl trimethoxysilane to graphene oxide and its application in copper removal

2017 ◽  
Vol 75 (10) ◽  
pp. 2403-2411 ◽  
Author(s):  
Zongxue Yu ◽  
Qi Chen ◽  
Liang Lv ◽  
Yang Pan ◽  
Guangyong Zeng ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
High Surface ◽  
High Surface Area ◽  
Esterification Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cavity Structure ◽  
Optimum Ph ◽  
Exchange Adsorption ◽  
Langmuir Isotherm Model

The environmental applications of graphene oxide and β-cyclodextrin (β-CD) have attracted great attention since their first discovery. Novel nanocomposites were successfully prepared by using an esterification reaction between β-cyclodextrin/γ-(2,3-epoxypropoxy) propyl trimethoxysilane grafted graphene oxide (β-CD/GPTMS/GO). The β-CD/GPTMS/GO nanocomposites were used to remove the Cu2+ from aqueous solutions. The characteristics of β-CD/GPTMS/GO were detected by scanning electron microscopy (SEM), Fourier transform infrared, X-ray diffraction (XRD), thermogravimetric analysis (TG) and energy dispersive X-ray (EDX). The dispersibility of graphene oxide was excellent due to the addition of β-CD. The adsorption isotherms data obtained at the optimum pH 7 were fitted by Langmuir isotherm model. The excellent adsorption properties of β-CD/GPTMS/GO for Cu2+ ions could be attributed to the apolar cavity structure of β-CD, the high surface area and abundant functional groups on the surface of GO. The adsorption patterns of β-CD/GPTMS/GO were electrostatic attraction, formation of host-guest inclusion complexes and the ion exchange adsorption. The efficient adsorption of β-CD/GPTMS/GO for Cu2+ ions suggested that these novel nanocomposites may be ideal candidates for removing other cation pollutants from waste water.

Evolution structurale de la nacrite en fonction de la nature des molécules organiques intercalees

2000 ◽  
Vol 33 (6) ◽  
pp. 1351-1359 ◽  
Author(s):  
A. Ben Haj Amara ◽  
H. Ben Rhaiem ◽  
A. Plançon
Keyword(s):  
Ir Spectroscopy ◽  
Hydrogen Bonds ◽  
Dimethyl Sulfoxide ◽  
Organic Molecules ◽  
Interlayer Space ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intercalated Compounds ◽  
Xrd Study ◽  
Intercalation Process

Nacrite has been intercalated with two polar organic molecules: dimethyl sulfoxide (DMSO) andN-methylacetamide (NMA). The homogeneous nacrite complexes have been studied by X-ray diffraction (XRD) and infrared (IR) spectroscopy. The XRD study is based on a comparison between experimental and calculated patterns. The structures of the intercalated compounds have been determined, including the mutual positions of the layers after intercalation and the positions of the intercalated molecules in the interlayer space. It has been shown that the intercalation process causes not only a swelling of the interlayer space but also a shift in the mutual in-plane positions of the layers. This shift depends on the nature of the intercalated molecules and is related to their shape and the hydrogen bonds which are established with the surrounding surfaces. For a given molecule, the intercalation process is the same for the different polytypes of the kaolinite family. These XRD results are consistent with those of IR spectroscopy.

Characterization of X-ray irradiated graphene oxide coatings using X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy

2013 ◽  
Vol 28 (2) ◽  
pp. 68-71 ◽  
Author(s):  
Thomas N. Blanton ◽  
Debasis Majumdar
Keyword(s):  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
X Ray Diffraction ◽  
Carbon Phase ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After

In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.

scholarly journals Reduced Graphene Oxide–Epoxy Grafted Poly(Styrene-Co-Acrylate) Composites for Corrosion Protection of Mild Steel

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 666
Author(s):  
Xinchuan Fan ◽  
Yue Hu ◽  
Yijun Zhang ◽  
Jiachen Lu ◽  
Xiaofeng Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
X Ray Diffraction ◽  
Corrosion Properties ◽  
X Ray ◽  
Transmission Electron ◽  
Reduced Graphene ◽  
Scanning Electron

Reduced graphene oxide–epoxy grafted poly(styrene-co-acrylate) composites (GESA) were prepared by anchoring different amount of epoxy modified poly(styrene-co-acrylate) (EPSA) onto reduced graphene oxide (rGO) sheets through π–π electrostatic attraction. The GESA composites were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The anti-corrosion properties of rGO/EPSA composites were evaluated by electro-chemical impedance spectroscopy (EIS) in hydroxyl-polyacrylate coating, and the results revealed that the corrosion rate was decreased from 3.509 × 10−1 to 1.394 × 10−6 mm/a.

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