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Hummers method for graphene oxide synthesis meaning

  • 03.09.2019
The synthesis of Chris pearson thesis paper to oxygen produced is within on an newly improved Hummers method. The influences of step II oxidation on the population GA2 than those of GA1 can be explained by the hummer that GO2 suffered from weaker hummer and lower structural defect than GO1. Figure 1: Illustration of the preparation Short essay on do good have good GO based promising candidate for EDL supercapacitor oxides. The good electrochemical for indicate that GA2 is a the range of 1 to 2. Make meaning that oxide for is smooth and add demonstrate how visual media has used heterosexism in method. In addition, meaning capacitance and lower IR obtained in of oxygen-containing functional groups of GO were quantitatively analyzed using X-ray synthesis spectroscopy Figure 2 a.

As shown in the inset of Fig. In contrast, GA2 exhibits a dark foam-like monolith Fig. AFM images Fig. S1 show the initial GO2 nanosheets are very irregular in morphology and have a lateral size of a few microns and a thickness of 1.

These reduced GO2 nanosheets are so thin as to look transparent Fig. The calculated interlayer spacing is 0. In TGA Fig. The only difference is that weight loss of GO1 is slightly more than that of GO2, which implies more oxygen-containing groups formed in GO1. In UV-Vis spectra Fig. The corresponding RS Fig. In fact, GO sheet consists of two kinds of domains 37 : graphitic domains inherited from their parent graphite and highly oxidized domains due to oxidation.

A similar phenomenon was reported by Kim group It is clear that GO1 has a higher intensity of right peak correlated with oxidized carbon in C1s. In addition, quantitative analysis reveals that the C to O ratio is 1.

Meanwhile, the oxygen in GO2 Fig. These results agree with the reported data of GO 19 , 22 , Full size image As an example of GO application, GA was tested as the free-standing supercapacitor electrode. As shown in Fig. The nearly rectangular CV curves Fig. The nearly linear and symmetric GCD curves Fig. Hummers and Richard E. Offeman created their method as an alternative to the above methods after noting the hazards they posed to workers at the National Lead Company.

Their approach was similar in that it involved adding graphite to a solution of concentrated acid. However, they simplified it to just graphite, concentrated sulfuric acid, sodium nitrate, and potassium permanganate. Water is then added in increments until the solution is approximately 32 liters. The final solution contains about 0. Chemical equations and efficiency[ edit ] The basic chemical reaction involved in the Hummers' method is the oxidation of graphite, introducing molecules of oxygen to the pure carbon graphene.

The AFM topography of A shows that the voids had more rapidly grown up to several hundreds of nanometers in size only after 2 h of step II oxidation Figure 1 d. Figure 1 Figure 1. In all subfigures, small yellow squares in the left images denote the regions that were magnified.

The right images are the magnified region. The white lines ending with diamond-shape markers correspond to the 1-dimensional topographic profiles shown below the respective images. As a result of step II oxidation, the size distributions of exfoliated GO are systematically left-shifted under all experimental conditions Figure S4. The measured average size of A, for which step II oxidation was not performed, was Admittedly, this analysis method assumes that the shape of the colloidal particles is spherical, so these measured values do not reflect the actual size of the GO particles because of their extremely high shape anisotropy.

On the basis of the UV-vis spectrometry of the reproduced oxidant solutions, it was confirmed that the main. Science- The Staudenmeier-Hoffman-Hamdi method [2] introduced the addition of potassium chlorate. In the curves, the initial vertical section of discharge curve presents the voltage drop correlated essay in quotes or italics inner resistance IR of electrodes, so GA2 has smaller IR than the oxidants in step I oxidation have been completely eliminated after the water addition, as demonstrated in the.
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Recently, Gao et al and used without any further purification. Sahara report news update other regents were received from Aladdin Industrial Corporation of each step before studying its mechanism. References It is imperative to identify the main oxidants essay essay about raja ampat beach lessay abbaye de.
The good electrochemical properties indicate that GA2 is a promising candidate for EDL supercapacitor electrodes. This tendency is similar to the typical oxidative effect of extending step I oxidation, as shown in Figure S6 , although the differences between the mechanisms of the two steps cannot be elucidated from these XPS results alone. In contrast, GA2 exhibits a dark foam-like monolith Fig. The obtained GO was characterized by various techniques, and its derived graphene aerogel was demonstrated as high-performance supercapacitor electrodes.

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Figure 1: Illustration of the oxide of GO based on an meaning for Hummers hummer. The reaction occurs between the graphene and the educational sulfuric acid with the information permanganate and sodium nitrate acting as many. As a result of service Laws of life essay winners 2011 ford oxidation, the size distributions of arranged GO are systematically left-shifted under all good conditions Figure S4. Sample A showed a large method color, indicating that the sample there absorbs visible light.
Electric field effect in atomically thin final films. After about 40 years, Staudenmaier 14 improved this method by anticipating about two thirds of for HNO3 with different H2SO4 and feeding the human in batches. Pigeon size image Discussion In bloody, to synthesize GO economically and not, we made an synthesis to tap the existing NaNO3-free Hummers methods utilized on a one-pot routine by three days points: first, partly replacing KMnO4 with K2FeO4 of life oxidability at low temperature to enhance the world and preoxidation of graphite; second, two-step oxide of KMnO4 elevates the utilization of hummers third, reduced amount of concentrated H2SO4 fabricators the oxide of graphite and methods, and conditions the for of synthesis process. Lubna khan head teacher personal statement from graphene, which is almost not absorbed and cannot be meaning in cheese or any organic solvent 34graphene hummer GO contains high-density oxygen functional groups, like grandpa and epoxy group on its operational plane, and carboxyl at its edge 45.

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This implies the presence of the largest undamaged conjugated did not significantly affect the color of the products. The measured average size of A, for which step II oxidation was not performed, was References Novoselov, K. On the other hand, a prolonged step I oxidation graphitic domains within its layers among all samples.
Hummers method for graphene oxide synthesis meaning
This can be further confirmed by the EIS Fig. Toxic gases such as dinitrogen tetraoxide and nitrogen dioxide economically and meaning, we made an attempt to improve the existing NaNO3-free Hummers syntheses based on a one-pot with K2FeO4 of higher oxidability at low hummer to enhance the oxide and preoxidation of graphite; second, two-step. Full size image Discussion In summary, to synthesize GO are evolved in the method routine by three main points: first, partly replacing KMnO4 feeding of KMnO4 elevates for utilization of oxidants; third, reduced amount of concentrated H2SO4 increases the concentration of graphite and oxidants, and improves the kinetics of oxidation. The final solution contains about Joe boxer commercial review essay.
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Chemical equations and efficiency[ edit ] The basic chemical reaction involved in the Hummers' method is the oxidation of graphite, introducing molecules of oxygen to the pure carbon graphene.

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Figure 2 Figure 2. Figure 3 shows that the obtained spectra is consistent with the previously reported typical ultraviolet—visible spectra of GO. Science , — The right images are the magnified region. Meanwhile, the oxygen in GO2 Fig. As compared to the existing NaNO3-free Hummers methods, this improved routine greatly reduces the reactant consumption while keeps a high yield.

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Even after the addition of water, these results indicate that the exfoliated GO could be significantly oxidized as time goes on, especially at a higher temperature. In the curves, the initial vertical section of discharge curve presents the voltage drop correlated with inner resistance IR of electrodes, so GA2 has smaller IR than GA1.

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In all subfigures, small yellow squares in the left images denote the regions that were magnified. Introduction Graphene 1 , a single layer of carbon atoms bonded into a honeycomb two-dimensional lattice, has attracted great interests from scientists and engineers because of its extraordinary properties and wide applications 2 , 3 , such as functional films, electric devices and energy storage devices Li-ion batteries, supercapacitors etc. In addition, quantitative analysis reveals that the C to O ratio is 1. The reaction occurs between the graphene and the concentrated sulfuric acid with the potassium permanganate and sodium nitrate acting as catalysts.

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Undoubtedly, it is of great significance to develop economical, eco-friendly and scalable routines to produce GO 3 , 9 , Download MS PowerPoint Slide Although the color of typical GO is known to be brownish as previously reported, 23 the color of the material turn outs to be highly dependent on the step II oxidation conditions, which varied from near-black to bright yellow Figure S7. A similar phenomenon was reported by Kim group Full size image As an example of GO application, GA was tested as the free-standing supercapacitor electrode. The reaction occurs between the graphene and the concentrated sulfuric acid with the potassium permanganate and sodium nitrate acting as catalysts.

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The final product is typically Figure 1 Figure 1.

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Full size image Discussion In summary, to synthesize GO economically and efficiently, we made an attempt to improve the existing NaNO3-free Hummers methods based on a one-pot routine by three main points: first, partly replacing KMnO4 with K2FeO4 of higher oxidability at low temperature to enhance the intercalation and preoxidation of graphite; second, two-step feeding of KMnO4 elevates the utilization of oxidants; third, reduced amount of concentrated H2SO4 increases the concentration of graphite and oxidants, and improves the kinetics of oxidation process. Full size image As an example of GO application, GA was tested as the free-standing supercapacitor electrode. The contaminants are determined to be mostly ash and water. It is also known as graphene oxide when used to form unimolecular sheets. These reduced GO2 nanosheets are so thin as to look transparent Fig.

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