Graphene - Science topic

I usually use Raman spectroscopy to characterize graphene peak and I have issues about Raman peak shift during the analysis. I have two problems during the Raman work.

1. I usually collect data several times (2-3times) at the same spot just to make sure the datas I collected are trustworthy. But every data at the same spot with nothing (power, location, etc,.) changed has different wavenumber.

2. I mostly used the spectroscopy to track the state of the graphene. Like the peak shift of graphene due to acetone (which is known to cause p-doping), PMMA spin coated graphene and lastly PMMA removed graphene because as I did some research about them, the cleaner the graphene is, red shift must occur (towards the prisitne graphene). But the theory doesnt work for me. It does not have any tendency.

I wonder if anybody has same issues like i have.

I am guessing this problems are caused due to

1) old device (Witec alpha 300M+)

2) bad focusing of laser

3) I use exfoliated graphene which is composed of many different layers around the spot i focused on (I dont know whether it matters)

4) Lastly, the power. The device's power management of laser is done through nobe not by giving numbers to the program and therefore the power won't be exactly the same. (I raise power where the peak saturation occurs through oscilloscope) <- but how can this matter when i just click "single spectrum" at the same spot but still acquires data with different wavenumber of the same peak.

If anybody had problems like i dave and knows what might be the problem, any advice will be really appreciated. Thanks.

Hello everyone! I need suggestions and guidance about postdoc positions. I am planning to find a Postdoc (after 13 months, not now), but I have no idea about it. You all are very experienced people, and from your experience, can you suggest some suggestions or guidance about how to find it, how to deal with it, and how it will work? how to contact with professor (like it's the same as we apply for a PhD or different) Your suggestion can change my idea and vision, so please give me your valuable suggestions for my upcoming journey.

I am highly grateful to all of you for your early suggestions and guidance.

Muhammad Danish Ali

I would like to first simulate how glucose adsorbs on the graphene surface, and then calculate its adsorption free energy. Which one is more appropriate, NAMD or gromacs, or is QE more appropriate?

To increase the pH

Hi,

I want to calculate the magnitude of k point(in Brillouin zone) of graphene which has a hexagonal unit cell. The lattice parameters of graphene are given below:

&CONTROL calculation = 'scf' / &SYSTEM ibrav = 4 a = 2.46639 c = 18 ATOMIC_SPECIES C 12.0107 C.upf ATOMIC_POSITIONS (crystal) C 0.333333333 0.666666666 0.000000000 C 0.666666666 0.333333333 0.000000000 K_POINTS (automatic) 35 35 1 0 0 0

ibrav 4 has the following lattice vectors.

📷 (check attachment)

If I open the scf.out and choose a k point (as follows)

cart. coord. in units 2pi/alat k( 44) = ( 0.3000000 0.5773503 0.0000000), wk = 0.0300000

How can I calculate the magnitude of the |k| in the hexagonal reciprocal unit cell? considering that I know the value of (kx, ky, 0). The lattice is a parallelogram so that |k| does NOT simply equal to sqrt(kx^2+ky^2), right?

I bought graphene oxide powder from Sigma Aldrich, dispersed it in DI water, and vacuum filtered it to make a film. However I am unable to figure out whether it is graphene oxide film or reduced graphene oxide film because the resistance is 4-5kohm.

I am doing my research on water nanofiltration using graphene oxide membranes. I have created four graphene oxide layers using python script.

Now i want to add water to my graphene oxide layers. Here, water goes over the layers and oxygen groups on the layers can form electrostatic interactions with contaminants and it can clean water.

Please help me to find out how I can add water and make my water flow through the graphene oxide layers?

I'm using LAMMPS

i want to perform self-consistent field (SCF) calculations for monolayer graphene considering Rashba spin-orbit coupling (SOC) using Quantum ESPRESSO i want to find out band structure.

plz any one who'll help me to make scf file.

Hi,

I want to model a heterojunction using orthorhombic Bi2MoO6 slab and graphene. Since the lattice symmetry is different for both I need to make them same crystal symmetry. Therefore , I need to convert hexagonal graphene to tetragonal using vesta. Could anyone suggest the transformation matrix for the conversion?

please suggest any reference book or article related to how to construct the transformation matrix for the lattice conversion

Thank you

Why for monolayer graphene I2D/IG value is 4 and for bilayer graphene it is 2? What are the physical significances behind this? All scientific answers and explanations related this are highly appreciable.

Does reduced graphene oxide successfully nitrogen/sulfur dual doped?

different methods apart from e-beam

apply both chitosan and graphene oxide on cotton fabric for improved anti bacterial property and improved strength of cotton fabric.

Graphene Oxide Preparation

Modified hummer method or LPE in aqueous medium for graphene preparation need to be dried in Vacuum oven rather than binder ovens. Is there a significant reason for this vacuum drying?

I want to resimulate a terahertz application using an ion gel layer with graphene. I know only the refractive index, which is 1.42, and the thickness of 0.15 um.

My question is, how to add this ion gel layer in CST MWS?

I want to know what is different between XRD of graphene and graphite?

Hello community,

I am studyng the electrochemical behaviour of some series of materials based on graphene oxide chemically modified with aliphatic amines attaching palladium nanoparticles. I am not familiar with electrochemistry so I really need help to make a correct interpretation of the voltammograms obtained and what essencially the graphs mean. I would really appreciate your help and further comments and suggestions.

I am in search of a modified Hummer's method, which can be used to synthesis graphene oxide within 6-8 hours.

As I am a student it is not allowed for us to work after 5 in the laboratory. So I am looking for a method to use in this regard.

Thanks and Regards.

The starting material is a finely ground powder. Some particles contain more graphene than others.

Please, can any one inform us about risks of graphene and graphene oxide as a factor of cancer growth?

I cannot get the Raman spectrum for carbon based materials like graphene in Raman spectroscopy of 785 nm . What can be done for obtaining the proper Raman peaks for carbon based materials in 785 nm Raman Spectroscopy.

difference entre les electrodes en nanotube de carbone et graphene en qualité d'adsorption

Please help me.

It is said that graphene layers accumulate again if they are produced and are not in a suitable solvent. So how are these pristine graphene powders supplied? I do not mean graphene oxide or fictionalized graphenes.

I am able to prepare Go and Rgo which I have confirmed with Xrd data but sponge formation is difficult. initially solid sponge type structure was formed but it was Fragile .

Actually my main aim is to work on various application . Can I use graphene powder and work on application pls suggest .

Thanking You

Currently, I want to investigate the structural, electronic, and other properties of a composite material, but have trouble in developing the necessary input file for Quantum ESPRESSO (QE). So that I am requesting assistance on how to develop the appropriate input file for QE to study the properties of the composite material. eg. ZnO/Graphene

I've been working on graphene ink for a while now and have encountered some issues with its spreading on paper. I'm uncertain whether the problem lies in the ink formulations or the size of the graphene particles.

My typical process involves chemically intercalating #2 flake graphite and expanding it in the microwave, followed by ultrasonication in an ammonium carbonate solution. After sonication, the few-layer graphene sinks to the bottom, where it can be collected and dried in a desiccator or vacuum oven.

I've experimented with various ink formulations, but none of them seem to spread satisfactorily. The formulations I've tried so far are as follows:

First formula:

Solvent: 10 ml Ethyl acetate

Binder: 3 g Polystyrene

Plasticizer: 1 g Mineral Oil

Conductive Material: 800 mg Few-layer graphene powder

Second formula:

Solvent: 20 ml Water

Surfactants: 2 g PVP, 2 g Sodium Dodecyl Sulfate

Plasticizer: 0.5 ml Glycerin

Conductive Material: 1 g Few-layer graphene powder

Third formula:

Solvent: 10 ml Water

Binder: 5 g PVA

Plasticizer: 0.5 ml Glycerin

Conductive Material: 1 g Few-layer graphene powder

When I used the ink formulation with surfactants, it appeared to work better, although it still didn't spread as well as expected. The conductivity could be better but I've gotten around 40 ohms to 100 ohms so far between each formulation.

I suspect the issue may be related to the size of the graphene particles, as I initially used #2 flake graphite, which consists of rather large flakes. Despite attempting to intercalate and expand 5 and 44-micron graphite, I encountered no success. I have now ordered some 44-micron vein graphite in the hope that its structure will facilitate better intercalation and yield smaller particles suitable for ink. Does anyone have any suggestions regarding what might be going wrong here? I have attached an image of some test lines I've painted with the ink to get a better idea of what I'm talking about. As you can probably see in the image, the ink seems to bleed a bit. I'm unsure of the reason for this.

I've even attempted to use a high-shear mixer to break up the graphene particles into smaller ones however, the graphene continues to agglomerate, worsening the spreading quality. I even used a ball mill with 4mm ceramic balls in an attempt to mill the graphene into a finer powder but it to aglomerates and sticks to the ceramic balls. Any suggestions would be greatly appreciated!

How to synthesis manganese doped graphene oxide after the synthe of graphene oxide by Hummers method ?

I tried to prepare graphene oxide using hummer's method. But at the end, it tuned black instead of yellowish color. I am sure there must be a lot of places where i might have done wrong but not sure where. Does over stirring or not controlling the temperature could have done this? Or does aluminium foil react with the solution of (graphite+KMn04+C.H2S04+NaN03) ? Or does the mixing of the hydrogen peroxide very slowly could have caused this? Anyone who has idea about it?

i prepared graphene oxide by modified hummers method

I am planning to electrospun a water-soluble polymer with rGO.

I read an article (https://doi.org/10.1016/j.synthmet.2020.116364) regarding the direct conversion of anthracite into graphene in the presence of molten.

I would like to ask the view from experts regarding the modified methodology.

The authors described the methodology in the paper as follows.

1. Carbon black is first grinded into powder of about 500 mesh.

2. Before using, iron powder (purity, 98 %; size, 400 mesh) is washed with diluted hydrochloric acid (HCl) to remove quickly the iron oxide layer. Then carbon black mixed with iron in the ratio of 1:5 or 1:10 in weight.

3. The mixture is then transferred into corundum crucibles and calcined in a tube furnace at 1600°C for 6 h under a 0.3 L/min argon flow. Heating and cooling rate are set to 10 °C/min. 4. After cooling to room temperature, the calcined mixture is corroded in excessive 1-M HCl for 48 h followed by washing with DI water three times.

5. The solid product is dried for 24 h at 110°C in vacuum oven.

My questions are

(a)Can we reduce the synthesis temperature from 1600°C to lower temperature by using other metal powder?

(b) What is the role of argon in the production of graphene?

(c) Can we still produce graphene using this method if we only use chamber furnace without argon gas supply?

I need the views/opinions from experts.

I would like to learn the details coding GFET through SILVACO but need reference. Hoping anyone could help me

A single layer of carbon atoms arranged in such a honeycomb structure forms a single graphene sheet. Several sheets stacked one on top of the other are regarded as multi-layer graphene, up to the point where the material becomes graphite (usually over about 30 layers, although clear standardization is severely lacking at the moment). Graphite, a 3D crystal composed of weakly coupled graphene layers, is a relatively common material - used in pencil tips, batteries and many more. In graphene, each carbon atom is covalently bonded to three other carbon atoms. Thanks to the strength of the covalent bonds between carbon atoms, graphene boasts great stability and a very high tensile strength (the force in which you can stretch something before it breaks). Since graphene is flat, every atom is on the surface and is accessible from both sides, so there is more interaction with surrounding molecules. Also, the carbon atoms are bonded to only three other atoms, although they have the capability to bond to a fourth atom. This capability, combined with the aforementioned tensile strength and high surface area to volume ratio of graphene may make it appealing for use in composite materials. Graphene also enjoys electron mobility that is higher than any known material and researchers are developing methods to use this property in electronics. These futuristic properties of graphene made a future mobile oil with inclusion of gasoline products.

I would like to ask about the best conditions of sonication of graphite oxide in terms of apparatus (probe or bath), time and power in order to effectively exfoliate the graphite oxide without damaging the structure of GO sheets. The objective is to obtain water dispersion of about 5 mg/mL of the highest possible quality.

Thank you very much.

I am working to check the effect of particle size on the quality of graphene.

My suggestion is phase transfer or using a dialysis bag. Is there any way to precipitate sodium hydroxide?

Please introduce an article or journal about the application of elemental two-dimensional nanoparticles in dentistry.. Two-dimensional nanomaterials such as graphene, silicene, etc.

I established a model of Ca decorated graphene 2D material with c lattice constant 20A, and wanted to do hydrogen molecular adsorption, the process is like this

1 Optimize the graphene system structure under Ca decorated.

2 throw in two hydrogen atoms at a distance of 0.7A for molecular dynamics analysis.

But in the analysis I found that the two hydrogen atoms separated, and flow upward, and did not be adsorbed, is this right?.

Because When I set one hydrogen atom, it got adsorbed very quickly.

or how can i draw it

I need the particle size and the shape of graphene oxide in epoxy powder as shown in the following FESEM morphology

How do I prepare different concentrations of graphene oxide (1, 5, 10ug/ml) for MIC from the powered form of synthesized GO? Please explain the steps.

Common parameters would be 200C for 8 hours for activated carbon/biochar. How about graphene oxide? Does it differ?

Recently i read about CNT/graphene Hybrid and there are few variants of CNT/Graphene such as (10,0) - 10h, (12,0) - 12h. What does each character means ?

Hi, I want to synthesize graphene oxide from graphite flakes for the fabrication of a graphene oxide water filtration membrane. Can you plz suggest to me the best method of synthesizing?

Also, if possible, share the protocol of graphene oxide synthesis.

Hi, I am Abdul Samad, researching graphene oxide nanomaterials. I have synthesized graphene oxide by Hammer's method, and now I want to develop a graphene oxide membrane. I have tried to develop a membrane using the vacuum filtration method, but this method didn't work. Can anyone suggest the assay, accessible, and best method of fabrication of graphene oxide water filtration membrane?

Also, can anyone suggest the best dispersion agent for graphene oxide?

I am attempting to comprehend the performance of graphene/n-type semiconductor Schottky diodes in photodetector applications.

Given that silicon (Si) and germanium (Ge) have similar electron affinities, 4.05 eV and 4 eV respectively, it might be expected that their Schottky barrier heights with graphene would be nearly identical.

However, the dark current in graphene/Ge contacts is significantly larger, as evidenced by both literature data and my experimental observations.

Beyond Schottky barrier height, what additional factors should be considered to understand this discrepancy in dark current?

Is it possible to grow graphene on the vertical wall of a structure, for example on the vertical walls of a SOI waveguide?

There are various nanostructures available for graphene such as nanosheets, nanowires, nanoribbons etc. Among them which is known for its best electrical conductivity

CNP and Dirac point in Graphene

I can access to few-layer graphene (non-oxidized) of 3-8 layers thickness and 2-8 micrometers of diameter. Is it possible to break this material into particles of 50-100 nm averaged diameter using standard laboratory equipment without altering its oxidation state?

Thank you in advance

Or in other words, what are its benefits or what distinguishes it compared to other materials? What happens when graphene is used in a waveguide? I need a detailed answer please.

Hii,

Can anyone please suggest articles for preparation of conductive ink using CNTs/graphene/ nanoparticles, etc.?

I want to get a dried, highly reduced graphene oxide from a graphene oxide solution. Is it ok to dry the solution around 80C, 24h?

Thank you.

I am prepared a Graphene solution in DMSO with different concentrations. Then I deposit the solution on a simple glass substrate, but the issue is the film is very instable in term of sticking. It is very easy to remove from the glass.

So, what the possible way to improve the adhesive of the graphene solution with glass slides. thanks

Actually I am working on Graphene oxide base metal oxides nanocomposites. When I annealed the sample under 450°C for 1 h in muffle furnace in air. The sample had changed its colour and the GO was oxidized. Please suggest me the suitable temperature and time for annealing the GO based materials. Which gas is suitable under which the annealing process should be carried?

Hi everyone,

I am trying to study Li adsorption on graphene and Electronic properties (PDOS and band structure) using Quantum Espresso. Anyone can help me how to do it? Starting from how to build the files and the steps, if there is any information, sources website can help me please let me know.

I will really appreciate it.

In the co-adsorption system of graphene oxide and oxytetracycline with soil, after the adsorption equilibrium, all of the soil and a small portion of the adsorbed graphene and oxytetracycline can be precipitated by centrifugation, but there is no good method concerning the determination of oxytetracycline and graphene oxide in the supernatant

I need to develop a PRISM(BK7) based SPR biosensor based on large area MoS2 and Graphene monolayer. To achieve my aim my requirement is in following steps.

1. First gold(Au) layer deposition (50nm thickness) on flat BK7 glass plate(Refractive Index=1.51)  We will directly apply this chip on prism hypotenuse by using suitable adhesion material with similar refractive index to glass plate.  

3. Finally transfer of Graphene monolayer (1 cm × 1 cm ×  0.345 nm ) thin film on  MoS2  monolayer.

Dear All,

We used 0.45, 1.2 and 2.5 uM filter papers for vacuum filtration for during the sythesis of graphene oxide with the Hummers method for washing of the material after final treatment with H2SO4. But each time the filter papers get clogged before long and we cannot pass almost any distilled water.

What pore size of paper do you suggest we use?

Figure: Water remaining after 2 hours of vacuum filtration on 2.5 uM filter paper

Kind regards,

Hello Im Yuliana Jiménez Gaona, and I want to shared that the user Yuliana Gaona

is taking my research and already associated with her profile ResearchGate (https://www.researchgate.net/profile/Yuliana-Gaona).

These research items are mine, please confirm the authorship to add it to my profile.

1.Tunable optical and semiconducting properties of eco-friendly-prepared reduced graphene oxide.

2.Outcome of Ivermectin in Cancer Treatment: An Experience in Loja-Ecuador

3.Deep Learning Based Computer-Aided Systems for Breast Cancer Imaging : A Critical Review.

Thanks in advance.

Cheers Yuliana Jimenez

I am working on Graphene oxide/TiO2 nanocomposites. The samples are prepared by hydrothermal method. In order to investigate the electrical properties of these semiconducting material, please suggest me to prepare samples for Hall measurement.

For modelling graphene, the CST software includes both a graphene and a graphene-Eps model. The graphene model expressed in the CST with a thickness of 0.3 nm is considered a single layer of graphene, while the graphene-EPS model is expressed as a multilayer of graphene sheets with a suitable thickness. Whenever I use the ''graphene-EPS'' model and increase the chemical potential, it does not affect any changes while using the "graphene'' model. Even at 0 eV chemical potential, it reflects all waves.Now my question is: why does it reflect all waves, even in insulting phases? I suspect that I may have made mistakes while creating the graphene material.

Can anyone explain the possibilities of doping Zr, Ce, or any other rare metal in graphene oxide?

I prepare a 3D printed electrode for micro battery application. But it develops many cracks (shown in the image below) after drying at a very low temperature of around 35 degrees Celsius.

My ink contains active material (70%), binder (10%), carbon nanotube (10%), and Graphene oxide (10%). The solvent is either NMP or DMF, and the substrate is a Polyimide sheet.

Please suggest a way to overcome this issue.

please, can any one help me?

Currently I'm using Optimized Norm-Conserving Vanderbilt Pseudopotential from the link https://github.com/pipidog/ONCVPSP.

I'm remember this discussion in the past, and to get the correct value we need to add more orbitals to the pseudo-potential, if I remember correctly. Is there a reference that discusses this precision issue in Quantum ESPRESSO?

Is there an openly available pseudo-potential I can use to improve my data?

I had write matlab programme using kubo formula and plot the intra conductivity in the range of 1 thz to 10 thz using an article below but real part of conductivity is 3.5*10^-15 s/m is this result correct???? plz check the pdf and the figure

bcz in the article the real part of conductivity was 3.5 s/m

thank you all.