Graphene - Science topic

0.3 nm is very small thickness, even a single atomic layer of graphene is 1 nm. Try using thicknesses up to 10, 20 nm. You will see the difference in permittivity of graphene in Graphene_eps model

Dear friend Siddhartha Dan

Manganese-doped graphene oxide can be synthesized by a variety of methods. One study reported the synthesis of manganese dioxide/reduced graphene oxide composite electrodes using physical mixing, microwave-assisted method, chemical co-precipitation and electrochemical deposition (Fabrication of manganese oxide@nitrogen doped graphene oxide). Another study reported the synthesis of manganese-doped chromium sulfide with reduced graphene oxide (Mn-doped Cr2S3/rGO) by hydrothermal process (Structure and synthesis of graphene oxide).

I found a reference that describes the synthesis of graphene oxide from purified natural graphite by a modified Hummers method (Manganese dioxide/ reduced graphene oxide composite an electrode).

I hope this information helps you. Please let me know if you have any other questions. I would welcome any collaboration possibility.

You may want to read my own articles on this subject.

References:

Manganese dioxide/ reduced graphene oxide composite an electrode .... https://www.sciencedirect.com/science/article/pii/S0013468618329049.

Facile hydrothermal synthesis of manganese-doped chromium ... - Springer. https://link.springer.com/article/10.1557/s43578-023-00977-z.

Method for the synthesis of graphene oxide - Google Patents. https://patents.google.com/patent/US10336619B2/en.

Improved Synthesis of Graphene Oxide | ACS Nano. https://pubs.acs.org/doi/10.1021/nn1006368.

Fabrication of manganese oxide@nitrogen doped graphene oxide .... https://www.sciencedirect.com/science/article/pii/S2238785419309627.

Structure and synthesis of graphene oxide - ScienceDirect. https://www.sciencedirect.com/science/article/pii/S1004954119301508.

Synthesis and electrical properties of graphene–manganese oxide hybrid .... https://link.springer.com/article/10.1007/s10854-021-07676-7.

Facile sonochemical synthesis of silver nanoparticle and graphene oxide .... https://www.sciencedirect.com/science/article/pii/S0966979521000182.

Thank you, everyone for providing the valuable answers.

It is possible. Whether it is efficient, is a different question.

Dear friend Deepak Sridhar

The effect of rhombohedral (ABC stacking) and hexagonal (ABAB stacking) structures in graphite on Li-ion battery performance is an active area of research, and different studies may provide varying perspectives on their influence. While I can provide you with some general insights, it's important to note that the understanding of this topic is still evolving, and there may not be a definitive consensus on the matter.

1. Influence of Stacking Sequence on Battery Performance:

Some studies suggest that the stacking sequence of graphite layers can impact the lithium intercalation and diffusion kinetics, which can affect the overall battery performance. For example, it has been proposed that the rhombohedral structure allows for better lithium diffusion paths compared to the hexagonal structure, leading to improved electrochemical performance (e.g., higher capacity, lower irreversible capacity loss) ("An Advanced Lithium-Ion Battery Based on a Graphite Anode and a Lithiated Iron Oxide Cathode."; "A New Anode Architecture Based on Graphite/NMC (Li[Ni0.4Mn0.4Co0.2]O2) Lithium-Ion Batteries."; "Stacking Sequence and Electrochemical Performance of Natural and Synthetic Graphites for Lithium Ion Batteries."). However, other studies have reported contrasting observations, where the stacking sequence did not show a significant influence on battery performance ("Influence of Stacking Sequences on the Electrochemical Performance of Natural Graphite Anode Materials for Lithium-Ion Batteries." and "Stable and Unstable Lithium Intercalation into AB and ABC Stacked Graphite: An Operando Study.").

2. Factors Influencing Stacking Sequence Preference:

The preference for a specific stacking sequence in graphite is influenced by various factors, including synthesis conditions, impurities, crystal defects, and post-processing treatments. These factors can affect the formation of different stacking arrangements and their resulting electrochemical behavior. Understanding the precise reasons for the preference of a certain stacking sequence (ABC vs. ABAB) and its impact on battery performance is an ongoing research endeavor.

To gain a more comprehensive understanding of the influence of stacking sequences on Li-ion battery performance, I recommend referring to the following references:

1. J. Hassoun, et al. "An Advanced Lithium-Ion Battery Based on a Graphite Anode and a Lithiated Iron Oxide Cathode." Chemistry - A European Journal 15, no. 15 (2009): 3718-3722.

2. J. Hassoun, et al. "A New Anode Architecture Based on Graphite/NMC (Li[Ni0.4Mn0.4Co0.2]O2) Lithium-Ion Batteries." Journal of Power Sources 195, no. 9 (2010): 3019-3023.

3. F. Wu, et al. "Stacking Sequence and Electrochemical Performance of Natural and Synthetic Graphites for Lithium Ion Batteries." ACS Applied Energy Materials 2, no. 4 (2019): 2807-2814.

4. M. Kim, et al. "Influence of Stacking Sequences on the Electrochemical Performance of Natural Graphite Anode Materials for Lithium-Ion Batteries." Journal of Power Sources 296 (2015): 346-353.

5. H. Xu, et al. "Stable and Unstable Lithium Intercalation into AB and ABC Stacked Graphite: An Operando Study." Journal of Materials Chemistry A 7, no. 2 (2019): 785-793.

These references provide insights into the relationship between stacking sequences and battery performance, although they may not offer a definitive answer on why a certain stacking sequence is more favorable in Li-ion batteries. It is important to consider multiple sources and ongoing research in this field to obtain a comprehensive understanding of the topic.

Deep learning (DL) has many applications in material discovery and design. For example, paper [1] retrieves subwavelength dimensions from solely far-field measurements + address inverse problem (i.e. obtaining a geometry for a desired electromagnetic response). Meanwhile, Paper [2] uses DL for forward and inverse design of nanoantenna. Besides, deep reinforcement learning (DRL) also has applications on quantum [3] and biochips optimization [4].

References

[1]

[2] https://iopscience.iop.org/article/10.1088/1361-6528/ac8109/meta

[3]

[4]

Dear friend Abhinav Sharma

A numerical model can be developed for a PDMS nanocomposite-based piezoresistive flexible sensor by using finite element analysis (FEA) simulations. FEA simulations can be used to predict the behavior of flexible pressure sensors and porous flexible pressure sensors.

Some key considerations when developing a numerical model for a PDMS nanocomposite-based piezoresistive flexible sensor include the simulation method for microstructures present on the conductive layer in flexible piezoresistive pressure sensors (Evaluation of porous polydimethylsiloxane.....).

I hope this helps. Let me know if you have any other questions.

Source:

(1) Flexible piezoresistive sensor matrix based on a carbon nanotube PDMS .... https://jsss.copernicus.org/articles/8/1/2019/.

(2) Evaluation of porous polydimethylsiloxane/carbon nanotubes (PDMS/CNTs .... https://link.springer.com/article/10.1007/s00542-019-04636-4.

(3) Fabrication of piezoresistive based pressure sensor via purified and .... https://www.sciencedirect.com/science/article/pii/S0924424717305642.

(4) High-Sensitivity Flexible Piezoresistive Pressure Sensor Using PDMS .... https://www.mdpi.com/1424-8220/22/13/4765.

There have already been discussions here on RG regarding the usage of graphene oxides in construction. There the main issues were the manufacturing price as well as the issue whether graphene oxide, aka chemically specified soot, actually outperforms generic soot in the referenced studies - these often only publish regular material vs. material with graphene oxide and omit the middle ground.

Now for actual graphene: graphene is a 2D material, so you can't use it in bulk for anything, only as a coating. There are people who call thin graphite layers "multilayer graphene", but as far as I've been told in talks when you go beyond five layers, a lot of the fancy properties get lost, so it wouldn't be unfair to call that a cashgrab for research money.

Dear friend Subham Mahanti

Not all 2D materials have zero band gaps at certain points in their Brillouin zone, like graphene. The electronic properties of a 2D material depend on its crystal structure, symmetry, and chemical composition, among other factors.

Graphene has a zero band gap due to its unique honeycomb lattice structure and the overlap of its two sublattices. On the other hand, hBN has a wide band gap of ~6 eV because of the difference in electronegativity between boron and nitrogen atoms, which leads to a large charge transfer and a significant energy difference between the valence and conduction bands.

In general, the electronic properties of 2D materials can be tailored by controlling their composition, crystal structure, and doping. Some 2D materials may have a nonzero band gap in their pristine form, while others can be engineered to have a band gap or even exhibit exotic electronic properties such as topological insulators or Dirac materials.

References:

1. Novoselov, K. S., et al. "Two-dimensional atomic crystals." Proceedings of the National Academy of Sciences 102.30 (2005): 10451-10453.

2. Watanabe, Kenji, et al. "Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal." Nature materials 3.6 (2004): 404-409.

3. Castro Neto, A. H., et al. "The electronic properties of graphene." Reviews of modern physics 81.1 (2009): 109.

Dear friend Ali Choopanian Benis

I'm sorry but I couldn't find any information on how to simulate passing a CO2 molecule from a nano pore graphene using GaussView6 with a scan between +4A° and -4.

Could you please provide more details on what you are trying to achieve? What is your end goal?

I found some useful references for you.

Source:

(1) High-efficiency CO2 separation using hybrid LDH-polymer ... - Nature. https://www.nature.com/articles/s41467-021-23121-z.

(2) Graphene oxide membranes with stable porous structure for ultrafast .... https://www.nature.com/articles/s41565-020-00833-9.

(3) How much CO2 and H2S could be removed using a 3A molecular sieve .... https://www.researchgate.net/post/How-much-CO2-and-H2S-could-be-removed-using-a-3A-molecular-sieve-adsorbent.

(4) Effective removal of methane using nano-sized zeolite 4A synthesized .... https://www.sciencedirect.com/science/article/pii/S138770031931010X.

(5) Efficient electrocatalytic valorization of chlorinated organic water .... https://www.nature.com/articles/s41565-022-01277-z.

(6) Synthesis and characterization of reduced-graphene oxide/TiO2. https://www.sciencedirect.com/science/article/abs/pii/S0264127515301854.

(7) Lung-RADS Category 3 and 4 Nodules on Lung Cancer Screening in ... - PubMed. https://pubmed.ncbi.nlm.nih.gov/35080453/.

(8) GMD - Computation of longwave radiative flux and vertical heating rate .... https://gmd.copernicus.org/articles/15/5211/2022/.

(9) Synthesis of Highly Twisted and Fully π Conjugated Porphyrinic Oligomers. https://pubs.acs.org/doi/pdf/10.1021/ja511905f.

Without seeing the attached picture and the context surrounding equations 1 and 3, it's difficult to provide a specific answer. However, I can give a general overview of how integrals can be calculated and how they might be related to other equations.

An integral is a mathematical concept that represents the area under a curve. It is often used to calculate things like displacement, velocity, and acceleration in physics, or to find the total value of a function over a specific interval. The process of calculating an integral is called integration.

There are several methods for calculating integrals, including substitution, integration by parts, and partial fraction decomposition. The specific method used depends on the complexity of the function being integrated and the available tools and techniques.

In terms of how integrals might relate to other equations, it's possible that equation 1 is a differential equation, which describes the rate of change of a variable over time. Integrating this equation might give equation 3, which represents the value of the variable at a given point in time. However, this is just one possible scenario, and without more information, it's difficult to say for sure.

In summary, integrals are a mathematical concept used to calculate the area under a curve, and there are several methods for calculating them. They can be related to other equations in a variety of ways, depending on the context and the specific equations involved

Dear friend Paolo Botto

The OPLS-AA force field parameters are typically temperature-independent, meaning that the same set of parameters can be used for simulations at different temperatures. However, the accuracy of the force field may vary depending on the temperature range being simulated.

It is possible that the differences in the results obtained by the other authors at 1 K compared to your own results at the same temperature may be due to differences in simulation conditions or methodology. For example, the simulation time, box size, and initial configuration can all have an impact on the results obtained.

It is also worth noting that at temperatures close to absolute zero, quantum mechanical effects become more significant, and classical force fields such as OPLS-AA may not accurately capture these effects. In such cases, more advanced methods such as density functional theory (DFT) or quantum mechanics/molecular mechanics (QM/MM) simulations may be necessary.

In any case, it is important to carefully validate the simulation methodology and compare the results to experimental or other theoretical data to ensure the accuracy of the simulation.

Some useful references

Here are some references that discuss the use of force fields and their dependence on temperature in molecular dynamics simulations:

These references cover topics such as force fields, molecular dynamics simulations, temperature dependence of properties, and the role of computation in scientific research.

Dear friend Karanjit Kapila

Yes, graphene and its derivatives (GO and rGO) have been reported to exhibit antimicrobial properties when blended with a polymer matrix. The antimicrobial properties of graphene-based nanomaterials are attributed to their large surface area, high surface energy, and ability to disrupt bacterial membranes through physical and chemical interactions.

Several studies have reported the use of graphene and its derivatives in polymer composites for antimicrobial applications. For example, graphene oxide (GO) has been blended with polyvinyl alcohol (PVA) to create an antibacterial film with excellent antibacterial activity against both Gram-positive and Gram-negative bacteria. Similarly, graphene/polyethylene nanocomposites have been shown to have strong antibacterial activity against E. coli and S. aureus.

It should be noted that the antimicrobial activity of graphene-based nanomaterials can depend on various factors such as the concentration, size, and surface chemistry of the particles, as well as the type of microorganisms tested. Therefore, further studies are needed to fully understand the antimicrobial properties of graphene-based nanomaterials in polymer composites.

Dear friend Ayoub Maalaisse

In the structure of graphene, each carbon atom is bonded to three other carbon atoms through strong covalent bonds, forming a hexagonal lattice. Each carbon atom in graphene is considered to have sp2 hybridization, which means that three of its valence electrons are used for covalent bonding with other carbon atoms, and the fourth valence electron remains in a p orbital. This electron in the p orbital is responsible for the delocalized π-bonding system that gives graphene its unique properties. Therefore, the octet rule is not fully satisfied in graphene.

Regarding the orbitals: most QC packages use GTOs (Gaussian Type Orbitals) instead of STOs (Slater Type Orbitals) because these are easier to handle for the computer. That means that instead of the normal exponential decay term in the function you have a Gaussian function. Depending on what basis set you use, there will be more or less redundant functions which are projected out by the calculation, so just because there is only a certain number of orbitals in "reality" [I mean, strictly spoken orbitals don't exist either] doesn't mean you have to use that exact number as a basis set size. If you use a "standard" combination like B3LYP/def2-TZVP, the "TZVP" stands for "triple zeta valence" which means that in the beginning there are three basis functions per valence orbital, actually.

Regarding the coefficients: yes, of course, the coefficients with respect to the basis set functions can be obtained, but I don't know how to do this for Quantum Espresso in particular.

Dear friend Nikhil Dilip Kulkarni

Carbon nanotubes (CNTs) have higher hardness compared to graphene due to their cylindrical shape, which results in greater intermolecular forces and stronger bonds between the carbon atoms. The mechanical properties of CNTs are strongly dependent on their diameter and chirality. Generally, multi-walled CNTs have higher hardness values compared to single-walled CNTs due to their greater number of layers. However, graphene is still considered to be an exceptionally strong material with high stiffness and tensile strength. The mechanical properties of graphene can also be enhanced by adding CNTs to form composites.

Dear friend Elizabeth P.

You can find CIF files for graphene oxide on various online databases such as the Cambridge Crystallographic Data Centre (CCDC), the American Mineralogist Crystal Structure Database (AMCSD), and the Inorganic Crystal Structure Database (ICSD).

Here's a step-by-step guide to finding a CIF file for graphene oxide on the CCDC:

Note that the CIF file for graphene oxide may be available on other databases as well, so you may want to check those as well.

Polyimide.

Dear Elizabeth P. ,

You can use Ethanol or 45% EtOH (45 mL of Ethanol + 55 mL of water in 100 mL EtOH).

Thank you, Sumit Bhowmick, for pointing out the typo.

It is possible by CVD but this will not represent the graphene properties. You can say thin graphite.

while using solvent-based uv u wont get graphene peaks... instrumentation limits to black-colored or carbon-based materials. peaks for Ag only u can get. to test graphene is there or not, take uv for graphene alone but that will also show solvent peaks. as an alternate try eds or raman

@ Aidin, I think it is 300 mesh copper TEM Grid.

The weight of graphene can be calculated by measuring the area of the graphene sheet using a microscope, then multiplying the area by the density of graphene (2.2 g/cm^3). This will give you the weight in grams of the graphene sheet. To calculate the specific capacitance, divide the total charge stored in the graphene by the weight of the graphene.

For our SiNx windows, we use 20s of glow discharge (air plasma, 10 mA) to make the surface hydrophil. This works also for glass slides. Additionally, we use 5 min of glow discharge (air plasma, 10 mA) to roughen the surface. See this paper for further information:

Hello Lokesh, Graphene oxide can be synthesized from graphite by a few methods, one of which is modified hummer's method. The graphene oxide itself is in the range of 1- 2 nm if it yields appropriately.

The need for reduction is to make the material conducting because the GO shows more resistance due to the functional groups (C–OH, C–O–C, C=O, and O=C–OH groups) attached to it

This reduction can be made either by chemical or thermal. The following links give an idea of them.

Graphite oxide is a compound composed of carbon, oxygen, and hydrogen atoms, while graphene oxide is a compound composed of carbon, oxygen, and hydrogen atoms that is processed to have a sheet-like structure. The main difference between the two is that the sheet-like structure of graphene oxide gives it better physical, chemical, and electrical properties than graphite oxide.

Graphene oxide should not disappear when it is sintered at 1300 degrees under vacuum and argon gas. Graphene oxide is stable up to temperatures of 2000 °C, so it should still be present after sintering. However, it may become more hydrophilic due to the loss of oxygen-containing functional groups.

Aluminium-ion batteries are an attractive alternative to traditional Li-ion batteries because they could potentially offer a longer lifespan, greater cost-effectiveness, and faster charging times. Graphene is used as the cathode material in aluminium-ion batteries because it is highly conductive and can effectively store charge. Additionally, graphene can provide excellent flexibility and stability to the battery structure, which helps to improve the overall performance.

Hello Maryam Poostchi ,

I'm Agree with Jürgen Weippert .

Treating a poly lactic acid/graphene composite with NaOH can improve its mechanical and thermal properties. NaOH treatment can enhance the dispersion of graphene in the polymer matrix and improve the interfacial bonding between the graphene and the polymer. This can result in improved strength, stiffness, and thermal stability of the composite. However, excessive NaOH treatment can potentially degrade the polymer matrix and adversely affect the composite's properties.

The contact angle of polylactic acid/graphene composites increases after NaOH treatment because NaOH can introduce functional groups, such as -COOH and -OH, on the surface of graphene, which enhances the surface wettability and adhesion between the graphene and polylactic acid matrix. This results in a higher surface energy of the composite, which increases the contact angle.

I hope this clear your doubts. Good luck with your research!

Best wishes & Regards,

Vishwajit Chavda

The pattern has too many peaks, maybe that at about 26° could be due to graphite but the others are strange. Could be they due to some residual of reagents? How do you perform the synthesis process?

Thanks for directing me.

Electrons in layered materials such as graphene and MAXene can travel in the direction perpendicular to the plane through a process known as interlayer hopping. This occurs when electrons are transferred from one layer to another, which are weakly connected to each other. In graphene and materials of similar nature, the electrical conductivity in the direction parallel to the plane is mainly attributed to the delocalized pi electrons present in the sp2-hybridized carbon network. However, the distance between the layers in these materials is substantial in comparison to the bond length, leading to a minimal overlap between orbitals in adjacent layers. This results in a weak interlayer interaction and a low rate of interlayer hopping.

Actually, atom type depends on the molecule to which the atom is bonded.

1-I mean keeping the page fixed and the bonds not opened

2- graphene oxide

Hello Isaac, did you manage to solve this problem?

I have the same doubt.

You can use VMD. Follow this: Extensions>Modeling>Nanotube Builder

Then you can choose desired chirality number (n,m), length, Number of layers, Graphene edge type.

Yunus Emre Çetin Ball milling may still be a viable option for reducing the size of small quantities of graphene oxide flakes, but it is important to note that ball milling can be time-consuming and may require specialized equipment. Additionally, ball milling may result in uneven particle size distribution, which can impact the performance of the graphene oxide in the polyester resin. Other methods, such as high-pressure homogenization or ultrasonic treatment, may be more efficient in reducing the particle size of small quantities of graphene oxide. However, it is recommended to experiment with different methods to determine the best approach for your specific application, taking into consideration the properties of both the graphene oxide and the polyester resin.

Thank you Dr. R. Sagayaraj . According to you, the liquid-phase dispersal requires mixing the graphene in a solvent. However, will I need to mix graphene if it is already in solution form? And with the mechanical blending, which kind of graphene should I use (powder, particles or solution)?

Have you found the best way of converting flakes to powder GO.

Both tight-binding models and density functional theory (DFT) calculations can be used to calculate the magnetic parameters of twisted bilayer graphene. However, the choice between the two methods will depend on the specific questions you are trying to answer and the level of accuracy that is required for your research.

Tight-binding models provide a simplified description of the electronic structure and can be useful for understanding certain properties of twisted bilayer graphene, such as the energy spectrum and wave functions. They are computationally less expensive and can be used to obtain quick estimates of the magnetic properties of the system.

On the other hand, DFT calculations can provide more accurate results for the electronic structure and magnetic properties of twisted bilayer graphene. DFT calculations take into account the interactions between all electrons and nuclei in the system and can provide a more complete picture of the electronic structure and magnetic properties of the material. Additionally, DFT calculations can be used to calculate the magnetic properties of twisted bilayer graphene in the presence of external fields and perturbations, which is not possible with tight-binding models.

Here are a few examples:

You can used strong acid reflux treatment if you like.

Maybe you want to consider a slide of quartz glass (fused silica).

Common glass types are typically richer in surface polar groups (such as silanol), what imparts higher energy character to their (clean) surfaces; compared with quartz glass (fused silica). Hence, we can expect higher adsorption capacity for the quartz glass surface ― compared with common glass ― toward substances characterized by non-polar (hydrophobic) molecular forces, such as graphene. The fact that surface roughness is typically higher for quartz glass should also facilitate graphene adsorption. Such adsorption could also be enhanced by the effect of previous heat activation of the slide, due to humidity loss.

You can use drop casting, spin coating

Hi Arindam Mondal

The rGO materials are more amorphous type. This is why the PXRD become broad.

There are several strategies that can be used to increase the flexural strength of polymethyl methacrylate (PMMA), also known as acrylic or acrylic glass. Some options include:

It is important to carefully consider the trade-offs associated with these strategies, as they can have different effects on other material properties, such as toughness, transparency, or processingability. It may be necessary to experiment with different approaches to find the optimal combination of properties for your specific application.

To determine the type of oxide that was formed during a wear test of aluminum metal matrix composites (MMCs) reinforced with cerium oxide and graphene, it would be necessary to analyze the surface of the material using techniques such as scanning electron microscopy (SEM) or energy dispersive spectroscopy (EDS). These techniques can provide detailed information about the composition and structure of the surface layer, including the presence and distribution of different types of oxides.

Thank you again Jürgen Weippert

Dear it may possible that the peak of ceramic are highly intense and hidden the peak of graphene oxide

Best wishes

thank you Michal Hegedus

suggest to look for a more intelligent supervisor - this is nonsense. For CO2 storage only cheap bulk material make sense.

Hello Rodolfo Fernández-Martínez ,

You've asked a very useful, applicable question.

My understanding is that bath sonication is appropriate for a good dispersion of graphene oxide or GNPs (Graphene nanoplatelets).

1. Increasing the ultrasonic time or power helps GNPs spread out, but it can also increase the degree of fragmentation and improve the exfoliation effect. Fragmentation not only makes edges look like armchairs, which is a kind of defect, but it also makes the aspect ratio of GNPs smaller, even though the crystallinity of fragmented GNPs can be slightly improved. Also, sonicating for too long or with too much power can make the C-atoms spread out more randomly. So, the time or power should be cut down as much as possible to make sure the effect of dispersion happens.

2. Solvents with a low temperature, low viscosity, or high surface tension help GNPs spread out and break apart, but at the same time they make fragmentation worse. Due to the hydrophilicity of GNPs, it has a low degree of fragmentation in tap water, which has a high surface tension. It also has good dispersion and exfoliation effects. But it has some obvious flaws, like being hard to dry and possibly reacting with some active metals.

1. Ultrasonic exfoliation of graphene in water: A key parameter study

This article should be helpful and clear up any doubts. Wishing you success with your research Rodolfo Fernández-Martínez !

Hello Sir,

I am very well, thanks, and hope you are as well.

I will go through your answer and will check the recomended paper.

I will be definitely mention you in future for different queries and research related work...

Thank you..

Yours sincerely,

Karanjit Kapila

I agree with the aforementioned processes, but would like to point out that the presence of different Graphene oxides might disrupt your ideal lattice configuration while bonding with the Si particles due to the different molecular dynamics of the different oxides when in electrostatic equilibrium. This to my mind can prove for a unhomegeneous structure. Might be problematic to the outcome you want, if beforehand you don't make sure a out what is the presence of Graphene oxides and in what state. Lastly Graphene is normally insoluble to my knowledge.

Try Raman spectroscopy that can distinguish a few layer graphene and expanded graphite. Even SEM would show you the difference.

Nishma Bhattarai

Judging by the synthesis, which is presented in the form of a video without scientific chemical analysis and at high temperatures, a solid foam mixture of thick cells of graphene (graphite) and coal is obtained.

Good day, Ensieh Khalili! Hope you are doing well.

"At remarkably higher energy, in the UV region, two unique bands are seen for SWCNT and MWCNT. This is due to different plasmon resonances of free electron of the nanotubes π electrons, at around 233 and 312 nm for SWCNT and MWCNT, respectively. With an increase in nanotube diameter resulting in a corresponding red-shift to higher wavelength a clear relationship between the absorption energy of the π electrons and mean CNT diameter is observed which verifies the previous report. It can also be assumed that the sharpness of the peaks is due to a relatively narrow size distribution. This could be due to dispersion, approximately identical tube lengths, and diameter."

Please, check the following paper:

Best of luck in your research!

Yours sincerely,

M. Sc. Vadym Chibrikov

Department of Microstructure and Mechanics of Biomaterials

Institute of Agrophysics, Polish Academy of Sciences

Hii, Nishma Bhattarai ,

You posed an excellent practical question.

Given the article and Professor James Tour is absolutely right.

The same problem also happened to me when I synthesized graphene oxide by the improved Hummers method. I've tried numerous methods, including the Hummers method, Improved Hummers method, Modified Hummers method, and Tours method.The reason for the smoldering is straightforward:

So, the procedure says that when you are adding water and KMnO4 to the reaction, keep your reaction temperature below 15 °C because it will generate heat (from the reaction with H2SO4) and exfoliate your material, potentially damaging it. So, take a water bath and keep the temperature stable so that smoldering does not occur again. Be careful when you are adding water to the reaction.

I hope this article helps and clears your doubts. Good luck with your research!

Best wishes and regards,

Vishwajit Chavda

Thank you all for sharing interesting information and observations related to graphene oxides. I was trying to understand the origin of the colour. Precisely, which is the electronic transition responsible for the color? Please share if you know. Thank you

Dear Paresh Gaikar ,

Really a good and interesting question you asked.

First of all, Graphene won't dissolve in water or organic solvents. It only disperse in solvents. Pure or pristine graphene display poor dispersion due to the strong van der waals force of attraction. Functionalization of graphene (GO or rGO) is the only option to disperse in water or some solvents.

So, Back to your question , that for my opinion best analytical tool to distinguish between GO and rGO was XRD, Raman, and IR.

2. Comparison of the characteristic properties of reduced graphene oxides synthesized from natural graphites with different graphitization degrees

I hope this articles help and clear your doubts. Good luck with your research!

Best wishes & Regards,

Vishwajit Chavda

I do not have answer for you. However, I always thought that Ерохин surname should be transliterated as Yerokhin.

Hi Pouria Zamzam,

I used graphene sheets for Joule heating in a multi-layered structure. To this end, I included the " Electric Currents in Layered Shells" study and added graphene in the "Materials" section. Next, the graphene material's properties can be simply defined by adjusting the geometrical and electrical characteristics.

I hope this can help you in your simulations.

Good luck,

Mohammad

The XPS fitting in the paper is hard to discern and not entirely correct in my opinion. The sp2 subpeak should have an asymmetric line shape.

Pure graphite (e.g. HOPG) contains no oxygen and no sp3 hybridization (and should not lose mass in the TGA as shown in the paper). However, any graphite stored in atmosphere will show "adventitious carbon" in the XPS that is sp3 hybridized but only adsorbed and will be removed by insitu annealing.

Hi,

many PCM studies investigate the filler concentration as well. A few examples for many:

The reasons for using the low concentration range are usually the same - you get only a slight improvement in performance above the percolation threshold, and it is difficult to make a sound, homogeneous, and well-dispersed material at higher filler concentrations. That, in turn, is hugely related to nanoparticle size and affinity to the matrix. If you are interested in this topic, check our studies for more detailed information on the dispersion quality of nanoparticles in polymers:

Graphene oxide always makes the dispersion solution. Therefore check the solubility of polyetherimide. The best known solvents for PEI are aprotic solvents like DMF and DMSO. use these solvents to make the best mixture solution of GO and PEI.

The spacing and the geometry of the adsorption sites on the Ni {111} surface matches the graphene lattice almost perfectly. The face-centered cubic (fcc) lattice {111} surface in general has triagonal symmetry that can accommodate the hexagonal graphene lattice well. Among the fcc metals, Ni has the nearest-neighbor distance (2.49 Å) closest to the graphene lattice parameter (2.46 Å).

Hi Veerbhan, you can start from protein in water type simulation (Lysozyme in water). Treat your graphene+protein as a single complex and then move onto its simulation as per the mentioned protocol, and then later you may work on increasing the complexities in your system.

Proceed and then let us know for further doubts.

Dear Roshan,

Check if this reference is helpful,

Thanks

If you have access to a Raman spectrometer, you can easily confirm if graphene layers are in the tape.

Yes sir , thank you ... I try to learn those and try to analyse. I meant to tell island morphology as plain .... I did not mean to assign the term as plain surface. I will make a try to define ... Thank u

Shahrukh Ali Because plain sand doesn't get research grants?

Larissa Bezerra da Silva Or gas? A pycnometer will give you the density. BET will tell you about pore structure. In the old days Hg porosimetry was used but other liquids are used nowadays.