Acidification Assisted Preparation of Graphite Oxide and Graphene

2014 ◽  
Vol 988 ◽  
pp. 36-39
Author(s):  
Yun Lei ◽  
Jun Xu ◽  
Rong Li ◽  
Fei Fei Chen
Keyword(s):  
Graphite Oxide ◽  
Test System ◽  
Ultrasonic Oscillation ◽  
Natural Graphite ◽  
Medium Temperature ◽  
X Ray ◽  
Hummers Method ◽  
Three Stages ◽  
Cyclic Voltammetry Test ◽  
Low Temperature Process

Graphite oxide was prepared by acidification assisted Hummers method, which contains acidification, medium temperature and high-temperature three stages. Traditional Hummers low-temperature process was replaced by acidification process. The dosages of acid, graphite and potassium permanganate were investigated, and the produced graphite oxide was treated by ultrasonic oscillation and reduced to graphene by refluxing the reaction mixture at 100°C under open-air conditions. The structure of natural graphite, graphite oxide and graphene were characterized by X-ray diffractometry and infrared spectrum, the morphology of graphene was observed on a scanning electron microscope and the electrochemical properties of graphene were analyzed by the three-electrode cyclic voltammetry test system.

Synthesis, Characterization and Thermal Behavior of  HYP2O7·3H2O Electrical Properties of  HYP2O7

2021 ◽  
Author(s):  
Rahma Rahzelli Zrelli ◽  
Fathia Chehimi-Moumen ◽  
Dalila Ben Hassen-Chehimi ◽  
Malika Trabelsi-Ayadi
Keyword(s):  
Infrared Spectroscopy ◽  
Electrical Properties ◽  
Complex Analysis ◽  
Optical Band Gap ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
Soft Chemistry ◽  
Medium Temperature ◽  
X Ray ◽  
Three Stages

Abstract The synthesis of the diphosphate HYP2O7·3H2O was made via soft chemistry route from evaporation of aqueous solution at room temperature. The obtained compound, was characterized by means of X-ray diffraction (XRD) and infrared spectroscopy (IR). The results showed a high purity phase. IR spectrum of this diphosphate revealed usual signals related to P2O7 diphosphate group and water molecules. The thermal decomposition of the synthesized product by DTA / TG proceeded through four stages leading to the formation of the Y2P4O13 as a final product. On the other hand, its decomposition by CRTA took place in three stages leading to the formation of the anhydrous diphosphate HYP2O7 as a final product. X-ray powder diffraction and infrared spectroscopy were used to identify these materials. Furthermore the electrical properties of the HYP2O7 were investigated through impedance complex analysis. Modest conductivity has been observed in this material at relatively medium temperature range. Activation energy of 0.67 and 1.44 eV, was deduced from the corresponding Arrhenius plot.The optical band gap of the title compound is calculated and found to be 2.71 eV.

Research on Preparation and Morphology of GO and GO/Fe3O4 Composite

2021 ◽  
Vol 1026 ◽  
pp. 117-121
Author(s):  
Zheng Miao ◽  
Rong Xia Zhu ◽  
Li Xia Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Phosphoric Acid ◽  
Graphite Oxide ◽  
Ultrasonic Treatment ◽  
X Ray Diffraction ◽  
Graphene Oxides ◽  
X Ray ◽  
Hummers Method ◽  
Scanning Electron

Graphite oxide was prepared from 325 mesh graphite (G) in this paper with methods of Hummers method,sulphuric/phosphoric acid method and reaction kettle method, the Graphene Oxides (GO) were obtained with ultrasonic treatment. Then Fe3O4 particles of two different proportions and hydrazine hydrate were introduced into one of the GO to obtain GO/Fe3O4 composites. X-ray diffraction (XRD) was used to characterize the G,the obtained graphite oxide and GO/Fe3O4 respectively. Scanning electron microscopy (SEM) was used to characterize the obtained GO and GO/ Fe3O4 composites.The results show that the GO obtained by the way of sulphuric/phosphoric acid has the best pattern and the nanoparticle scale decreased as the proportion of GO in GO/Fe3O4 increased.

Preparation and Characterization of Graphite Oxide

2013 ◽  
Vol 771 ◽  
pp. 3-6 ◽  
Author(s):  
Zhao Xia Hou ◽  
Yin Zhou ◽  
Shao Hong Wang ◽  
Mei Han Wang ◽  
Xiao Dan Hu ◽  
...  
Keyword(s):  
Graphite Oxide ◽  
Reduction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hummers Method ◽  
Absorbance Spectroscopy ◽  
Oxidation Reduction ◽  
Diffraction Peaks ◽  
Scanning Electron

The preparation of graphite oxide is one of essential steps for graphene by oxidation reduction method. Graphite oxide was acquired from the oxidation of graphite by improved Hummers method and characterized by X-ray diffraction, scanning electron microscope, Fourier transform infrared absorbance spectroscopy and thermogravimetric analysis. It was showed that the graphite interlayer distance of graphite oxide increased for a large amount of oxygen containing functional groups. Shift and broaden of diffraction peaks were observed after oxidation and the original graphite peaks disappeared.

scholarly journals Improved Water–Gas Shift Performance of Au/NiAl LDHs Nanostructured Catalysts via CeO2 Addition

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 366
Author(s):  
Margarita Gabrovska ◽  
Ivan Ivanov ◽  
Dimitrinka Nikolova ◽  
Jugoslav Krstić ◽  
Anna Maria Venezia ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Nanostructured Catalysts ◽  
Water Gas Shift ◽  
Precipitation Method ◽  
Conversion Degree ◽  
Pure Hydrogen ◽  
Medium Temperature ◽  
X Ray ◽  
Supported Gold ◽  
Water Gas

Supported gold on co-precipitated nanosized NiAl layered double hydroxides (LDHs) was studied as an effective catalyst for medium-temperature water–gas shift (WGS) reaction, an industrial catalytic process traditionally applied for the reduction in the amount of CO in the synthesis gas and production of pure hydrogen. The motivation of the present study was to improve the performance of the Au/NiAl catalyst via modification by CeO2. An innovative approach for the direct deposition of ceria (1, 3 or 5 wt.%) on NiAl-LDH, based on the precipitation of Ce3+ ions with 1M NaOH, was developed. The proposed method allows us to obtain the CeO2 phase and to preserve the NiAl layered structure by avoiding the calcination treatment. The synthesis of Au-containing samples was performed through the deposition–precipitation method. The as-prepared and WGS-tested samples were characterized by X-ray powder diffraction, N2-physisorption and X-ray photoelectron spectroscopy in order to clarify the effects of Au and CeO2 loading on the structure, phase composition, textural and electronic properties and activity of the catalysts. The reduction behavior of the studied samples was evaluated by temperature-programmed reduction. The WGS performance of Au/NiAl catalysts was significantly affected by the addition of CeO2. A favorable role of ceria was revealed by comparison of CO conversion degree at 220 °C reached by 3 wt.% CeO2-modified and ceria-free Au/NiAl samples (98.8 and 83.4%, respectively). It can be stated that tuning the properties of Au/NiAl LDH via CeO2 addition offers catalysts with possibilities for practical application owing to innovative synthesis and improved WGS performance.

The Synthesis and Characterization of the Graphene Oxide Covalent Modified Phenolic Resin Nanocomposites

2011 ◽  
Vol 327 ◽  
pp. 115-119 ◽  
Author(s):  
Duo Wang ◽  
Jie Gao ◽  
Wei Fang Xu ◽  
Feng Bao ◽  
Rui Ma ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Phenolic Resin ◽  
Synthesis And Characterization ◽  
Infrared Spectrometry ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Hummers Method ◽  
Modified Hummers Method ◽  
Thermal Stability Of

Graphene oxide (GO) was made by a modified Hummers method. Graphene oxide modified phenolic resin nanocomposites (GO/PF) were prepared by Steglich esterification, catalyzed by dicyclohexyl carbodiimide and 4-dimethylaminopyridine. The composites were characterized by Fourier transform infrared spectrometry, differential scanning calorimetry, X-ray powder diffraction, and scanning electron microscopy. The result revealed that the graphene oxide was absolutely exfoliated and covalent linked GO/PF composite was obtained. The thermal stability of PF is remarkably improved by modification with GO.

Synthesis of graphite oxide using hummers method: Oxidation time influence

2021 ◽  
Author(s):  
Nurhayati Indah Ciptasari ◽  
Nono Darsono ◽  
Murni Handayani ◽  
Johny W. Soedarsono
Keyword(s):  
Graphite Oxide ◽  
Oxidation Time ◽  
Hummers Method

150-kV pulsed X-ray test system

2015 ◽  
Vol 27 (6) ◽  
pp. 65005
Author(s):  
吴红光 Wu Hongguang ◽  
李玺钦 Li Xiqin ◽  
刘金锋 Liu Jinfeng ◽  
冯元伟 Feng Yuanwei ◽  
王晓 Wang Xiao ◽  
...  
Keyword(s):  
Test System ◽  
X Ray

200-kV flash X-ray radiographic test system

2013 ◽  
Vol 25 (6) ◽  
pp. 1401-1404
Author(s):  
吴红光 Wu Hongguang ◽  
赵延安 Zhao Yan’an ◽  
王晓 Wang Xiao ◽  
李玺钦 Li Xiqin ◽  
梁川 Liang Chuan
Keyword(s):  
Test System ◽  
X Ray

Crystallization trend of titanomagnetites in an alkali basalt from Saint-Clément (Massif Central, France)

1973 ◽  
Vol 39 (304) ◽  
pp. 474-481 ◽  
Author(s):  
M. Prévot ◽  
J. Mergoil
Keyword(s):  
Magma Ascent ◽  
Chemical Compositions ◽  
Common Belief ◽  
Massif Central ◽  
X Ray ◽  
Show Evidence ◽  
Ti Content ◽  
Crystallization Stage ◽  
Temperature Crystallization ◽  
Low Temperature Process

SummaryThree generations of homogeneous titanomagnetite in a hawaiite from Saint-Clément may be defined by differences in size, habit, or reflectance, and are believed to correspond to different crystallization stages of the lava. Chemical compositions were determined by electron microprobe, and by X-ray and thermomagnetic methods.Larger crystals are of intratelluric origin and occur either as inclusions in phenocrysts of early clinopyroxene (generation 1) or separately in the groundmass (generation 2); in the latter case, they always show evidence of resorption. Post-eruptive titanomagnetite (generation 3) is smaller and so highly oxidized that it is better termed titanomaghemite. Since the maghemitization, which is a low temperature process, alters the metallic ratios (especially the Fe/Ti ratio) the metallic contents at the time of the high-temperature crystallization are exactly known only for the intratelluric titanomagnetites.As intratelluric crystallization proceeds Ti content increases greatly (5 to 14%); Mn also increases (but slightly), A1 and Mg decrease, while results for Cr are inconclusive. Apparently these changes go on until the post-eruptive crystallization stage.The titanium trend is contrary to common belief. However, it is in accordance with predictions from the Fe-Ti-O system and may be explained by a decrease in oxygen fugacity during magma ascent.

The Effects of Cooling Rate Upon Xdt m TiAl Weld Microstructure

1990 ◽  
Vol 194 ◽  
Author(s):  
Erica Robertson ◽  
Mary Ann Hill ◽  
Ricardo B. Schwarz
Keyword(s):  
Solid State ◽  
Cooling Rate ◽  
Volume Fraction ◽  
Mechanical Test ◽  
Test System ◽  
X Ray Diffraction ◽  
State Transformation ◽  
Solid State Transformation ◽  
X Ray ◽  
Weld Microstructure

AbstractFusion zone microstructures of an electron beam (EB) welded XDt m Ti–48at%Al + 6.5 vol% TiB2 alloy revealed plate-like precipitates which were absent in the base metal. The volume fraction of this phase increased with increasing cooling rate and correlated with increased weld cracking frequency. To determine whether this phase was a product of solidification from the melt or a product of a solid-state transformation, the microstructures of the welds were compared to those of samples cycled in a Gleeble 1500/20 Thermal-Mechanical Test System which was programmed to simulate the solid-state portion of the weld cooling rates (as predicted by a Rosenthal analysis). The microstructures were characterized by X-ray diffraction, optical and by scanning electron microscopy. The plate-like phase found in the weld microstructures was identified as TiB2 occurring upon rapid solidification of the melted weld metal.

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