Carbon Nanomaterials - Science topic

Hello!

I work with carbon quantum dots (carbon nanoparticles with intense fluorescence) and I want to image them using a TEM. I have seen dozens of TEM images showing carbon quantum dots as dark objects on a bright background. I tried to deposit them on various grids (formvar-coated or formvar-carbon coated) and failed to observe them.

There could be two reasons for this. First, the carbon dots do not adsorb onto the substrate. Second, they adsorb, but I can't see them, because the contrast is too low (they are almost transparent for the electron beam). I tried staining the grid with UA, but it did not help.

I feel puzzled. Many researchers image various carbon dots as a routine, but I fail systematically.

Any hints?

what are differences between mechanism of heavy metal ions adsorption on activated carbon and mechanism of ion adsorption on volatege connected types of carbon electrodes?

Electrical field or functional group? Which factor really acts?

may a supercapacitor electrode without voltage absorbe ions?

Valence of ions are effective?

Hi All,

I work with nanomaterials. Especially with Carbon Dots, with fluorescent properties (Max emission at 650 nm and Max excitation at 400 nm, sizes around 2nm). When we use Confocal Microscope for cell internalization, we get no fluorescence. However, it is possible to detect the shift very clearly in Flow Cytometry. Still, I think I have no choice but the Confocal Microscope to track Carbon Dots inside the cell. (It is not easy to show that these materials are inside the cell in TEM as well). What could be the reason for this situation? does anyone have a similar problem? I need your help. Why can not we detect these nanomaterials by Confocal but we can detect them by Flow Cytometer?

What are the biggest technological challenges in the production of core-shell nanomaterials?

Can you please tell your experience and/or give comments on morphology control, synthesis precision, stability and durability, economic viability, etc.

I just need to know if I separate the carbon nanodots through the process of dialysis will it improve the color and become useable in applications. The carbon dots that I have now are just very cloudy or looked washed.

Hello,

I am preparing GO using hummers method as follows:

Briefly, 69 mL of concentrated H2SO4 was slowly

added to a mixture of graphite powder (3 g, 1 wt equivalent) and

NaNO3 (1.5 g, 0.5 wt equivalent) in a 500 mL beaker. The mixture

was cooled down to 0 ◦C in an ice bath and stirred for 1 h. Then,

KMnO4 (9.0 g, 3 wt equivalent) was slowly added in portions to

keep the reaction temperature below 20 ◦C. The beaker was then

placed in a 35 ◦C water bath and the solution was stirred for ∼1 h

to form a thick paste to which ultra-pure DI water (138 mL) was

added slowly, which produced a large 98 ◦C exotherm; maintained

atthis temperature for 15 min. Then, a mixture of DI water (420 mL)

and 30% H2O2 (10 mL) were added, producing another exotherm at

below 20 ◦C. Finally, the solution was filtered to obtain the precipitate.

i followed these instructions very closely, especially maintaining the temp, i got the green color after adding kmno4 and brown after adding water, however i was unable to get the bright yellow color on adding hydrogen peroxide, instead i got a dirty greenish brown color (pic attached). I did see yellow bubbles on adding h202 but the color of the whole solution does not change to yellow.../

My questions what does the color change to yellow indicate? If I am not getting it which step could the mistake be in?

Hello, I have been working on the synthesis of carbon dots (CDs) by electrochemical method, and I have been using monoethylene glycol as a surfactant agent, to avoid agglomeration of the CDs, however, agglomeration still occurs in the resulting solution, for this reason, I would like to know If anyone has any experience with any other type of surfactant or if someone could please guide me on what I may be missing to avoid agglomeration in the CDs.

In advance, many thanks to those who take the time to share their knowledge.

What is the band gap of MWCNT (not SWCNT)? Is it near about 2eV? 

If not, what could be it's electronic property? Are MWCNTs metalic like zigzag SWCNT or semiconductor or insulator?

Good Morning

 Please read my problem and give suggestions to resolve my issues. I am working on supercapacitor electrodes and i am using composite of carbon nanomaterials and metal oxide nanoparticles coated on commercial sponge(substrate) for electrode fabrication. My CV results seems to be good and calculated capacitance from CV curve is 600F/g. The actual problem is occurring in charge discharge measurement. I am using three-electrode system with 3MKOH electrolyte using Ag/AgCl as reference electrode. The problems that i am facing are;

1) The charging discharging curves are not of required shape.

2) The curves do not start from 0 and end at required designated voltage.

3) The applied current is very low but as i increase it, the shape of curve totally get change.

Please guide me whether my parameters for CDC measurement are not correct or i have some issues based on my materials or coating. I am attaching the word file which have four obtained curves including parameters that i have used to take measurement. The obtained CV curves are also attached. For your convenience, a file is also attached that have required curves. Waiting anxiously for your reply. Thanking in anticipation.

I am doing a sutdy about Carbon Nanomaterials in High Density Polyethylene, but its MFI is too low (0.4 g/10 min). Do anyone know any aditve such as an internal lubricant than could increase this MFI Value?

Our quantum dot(g-C3N4/CQDs) was prepared from melamine and then exposed to phenylbronic acid(PBA) for the next steps of the experiment - whose fluorescent properties were quenched (Figure 1) but after 5 days and quantum dot solution dialysis with PBA (1000D) A little of its fluorescent property back, what is your analysis?

Can solvent properties like dipole moment, surface energy, etc. influence the lattice orientation of nanomaterials -

i) during synthesis,

ii) re-dispersion in any solvent,

iii) re-drying after dispersing in different solvents,

iv) pH of the dispersion media

In our country, Iran, the price of a hydrothermal synthesis reactor is very high due to sanctions and the devaluation of the national currency, and I need to have the exact size of a 50 ml sample to design it with the help of SolidWorks software. Let me make it, does anyone have an exact design or size of it?

Nanoparticles are

1. Carbon nanodots

2. Bare Iron oxide Nanoparticles

3. Oleic acid capped nanoparticles

Hi.

We have some carbon nanoparticles and want to check antibacterial activity against drug-resistant bacteria. Before working on drug-tolerant bacteria, Are there any protocols or parameters for checking nanoparticles whether have the antibacterial capability on drug-resistant bacteria?.

I have synthesized carbon dots that exhibit fluorescent properties, that are further coated with PEG through EDC. I want to separate them through gel electrophoresis based on the number of PEG attachment. Is the gel electrophoresis for Carbondots any different than gel electrophoresis for nucleic acids ?

I would like to know some tips in the procedure to obtain palladium nanoparticles. Currently, I am placing in the same flask an acidic solution of palladium chloride and an aqueous solution of citric acid using carbon nanomaterials as substrates. Afterwards, I apply slight stirring during 10 minutes and finally I wash the substrate twice with water.

Could you tell me if I am in the correct or incorrect line or what other step I should do?

Thank you in advance for your help.

I'm looking for the JCPDS card number for graphene, graphene amine, graphene nanoplatelets, Carbon nanofiber for XRD analysis.

Hello, I am very new to using AFM and I have been trying to use it to image pristine MWCNTs (dia 20-30 nm, length 2 microm) and MWCNTs functionalized with -COOH and -NH2. I initially tried dispersing them using water and ethanol with no good results. Recently I have been using DMF as a dispersion medium (0.1 mg/ml CNTs and 0.01 mg/ml CNTs in DMF) and used sonication for the dispersion (1h and 2h). I used freshly peeled mica discs and put 5 microL and 10 microL of the solution (let it dry on its own and kept covered) and tried imaging using tapping mode AFM. However, the images (attached below) although filamentous look like sample drift rather than an actual image (and clumps of material). I have used different scales (10*10 microm, 5*5, 2*2) and different AFM tips but they all give out the same kind of image.

So my question is quite broad - for those of you who have successfully AFM imaged MWCNTs - how did you do it? What is causing the drift (assuming it is drift, I cannot think of another explanation) since I thought tapping mode is supposed to prevent very high forces? Another reason I think it is drift is because when it finishes the scan and scans back from top to bottom many of the structural contents seem to disappear or move to a different location. Additionally, the diameter and the length of the long filaments do not match that of the mentioned size of CNTs and the filaments look very straight. But since the tip is moving horizontally I can't figure out why there is a vertical drift?

Also side note- the MWCNTs used were manufactured in 2011 if that makes any difference.

Dear Researchers, I would like to open this discussion, I think it could be interesting and we participants can learn much from each other :

Is it well known that the so called reduced-size effects in Material Science can originate different behaviors in different properties of a given material (this is also known as "Nanomaterials", or "Nanostructured Materials")

Hence the question:

All Nanomaterials have higher Electric Conductivity than its bulk-size respective part ? The logic is that the DOS (Density of States) becomes (theoretically) infinite for some values of Energy in the material (the typical graph of E vs. g(E) for 0D Materials, which distributes this Energy discrete values in peaks, speaking of the shape).

So, this makes me think that for all solid materials; sigma increases (for this values of Energies) when the dimensions of the material decrease.

Regards !:)

Hello everyone.

I am studying the Soret effect of a solid-gel electrolyte in two electrode system, in which the active electrode materials are textiles coated with commercial carbon nanomaterials. So, I am doing some experiments measuring the thermovoltage (V_themo) over the electrolyte induced by a gradient of temperature (∆T) applied between both electrodes (soret effect).

I did these experiments for different ∆T, measuring the resulted V_themo. However, the V_themo does not tend to 0 mV when the ∆T is zero, as can you see in the graph.

My questions is: It is possible? Or something is wrong with the measurements? What could be happen?

Thank you for your help.

Carbon nanotubes are good conductor of electricity at room temperature its resistance is very less with negligible heat loss but is it possible to achieve Cooper pair effect at room temperature in carbon-nanotubes in the future?

Hi

Graphene quantum dots (GQDs) are so stable in water. It can be stable in water for several months.

What is the reason(s) for their high stability?

What is the interaction between GQDs (specially their functional groups) and water?

Is there hydrogen bonding?

Thanks for your answer.

What are the density and acoustic impedance values used for C60, graphene, SWNT, MWNT and graphene oxide in thermal evaporation, a physical vapour deposition process?

dear all, I am trying to finalize my Phd thesis (after few years break). My topic is nano-QSAR / QSPR modelling of halogenated (Br and/or Cl) POPs adsorption on the surface of a C60 fullerene. I do have a huge dataset for 23 groups of congeners (calculations) - but there is not much experimental or even theoretically calculated data for such interactions. Maybe someone knows any papers reffering to that topic? I will be grateful for any suggestions - although I believe that I already knew most of them before - it is always worth to ask :) Thanks for any help!

heloo experts,

I want to study the interaction between carbon nanostructures, for that i have planned to include vdw pseudos(vdw/DRSLL). When i run single point calculations over the relax geometry obtained from GGA/PBE with that of vdw pseudos i got atomic forces more than that from my relax geometry. kindly explain why i am getting so.? Does my way of doing calculations is accurate or not. ?

Can I predict the Young's modulus and Flexural Modulus of the MWCNT nanocomposites using Halpin Tsai equation? or using the single equation by only changing the Modulus value

I want to purchase grids for HRTEM measurement. Can anyone provide the suitable specification like the mesh size, grid material, etc., My particle of interest is carbon quantum dots which will have sizes from 1 to 10 nm.

Thanks in advance..

We've got some carbon quantum dots in a mixture of H2SO4 and HNO3. Can anyone help me out with any possible ways to separate these quantum dots from acid without adding any more ions to the solution?

i need to access source codes of a software that replicate hexagon and pentagon in space and create fullerene -like structure.

Hello All:

Does anyone is currently working, or know works about introducing carbon nanostructures in the material structure of the conventional thermoelectrics (like: Bi2Te3, Sb2Te3, Bi,SbTe, PbTe, ... ), or metallic, or metallic oxide Nps into these materials? To evaluate and enhance its thermoelectric properties ?

Some of these nanostructures could be :

C60 molecules, or others

Carbon Nanotubes

Graphite Nanoplatelets

Grephene Nanoplatelets

Graphene Oxide (nanoribbons, nanosheets, etc... )

Looking forward

Best Regards ! :)

I am going to research about supercapacitors, and will be used the porous carbon nanomaterials as electrodes derived from polymers. As I read literatures they said heteroatoms such as B, N, O, P, S can improve the conductivity of the carbon nanomaterials, and resulted in the improving of the capacitive performance of the supercapacitors. I am wondering how these hetero atoms can improve the conductivity of the carbon porous materials. I would very appreciate if anyone can explain the mechanism of this or recommend some books or literatures. Thanks a lot.

How to isolate a single 2-D layer of carbon nitride from bulk graphitic carbon nitride?

I prepared carbon soot with natural precursors. I want to dissolve carbon soot but I don't have any idea how to dissolve and which solvent is good for carbon soot. 

I found a paper about grafting silica nanomaterial to carbon fiber.

Shortly, 1) CF-COOH is made. 2) With a reflux reaction (at 50C, 4h), CF-COOH reacts with solvent including silica nanomaterial. 3) CF-CO-silica is made.

The silica nanomaterial has -OH functional group. So, it reacts with -COOH, and CF-CO-Silica is synthesized.

I want to apply this method to carbon nanomaterial, ex) cnt, go, ..

Then, how can I make the experimental setup ??

For example, ??g of CNT-COOH in ?? ml of ethanol & ??g of silica in ?? ml of ethanol have a reflux reaction

I can set the reaction time or tempearture from my reference paper. (CF-g-silica)

However, I don't know the amount of CNT and silica... for a proper reflux reaction and grafting.

I ask for your help.

I am really looking for the soft copy of this JCPDS card No.75-1621 that is mainly used to identify carbon nanomaterial

please insight us.

Hi

I am studying about porous carbon materials for using Li-S battery.

I'm using teflon to remove silica from porous carbon & SiO2 particles.

I used to teflon instead of NaOH when etching the silica.

But, there are some questions about the materials that comes out of pyrolysis in teflon.

Teflon is pyrolyzed to C4F8 (g) at 350~450 ºC. (in N2 gas)

C4F8 + 2SiO2 --> 2SiF4 (g) + 2CO2 (g) + 2C (major)

C4F8 + SiO2 --> SiF4 (g) + 2COF2 (g) + 2C (minor)

I believe that SiO2 is removed and COF2 is deposited on carbon, resulting in F-doped carbon.

I think that source of F-doping is COF2 (g).

But, I have not found the exact F-doping mechanism.

Help me. thank you

Metals have free electrons and a lattice structure favorable for the conduction of heat (thermal energy).

How are carbon nanotubes such good conductors of thermal energy? Is it just because of their structure, or is it something else?

The material (besides clay) needs to be non-reactive/stable, and preferably synthetic. Thank you very much in advance! Your suggestion is very much appreciated!

How is CNTs efficiency compared to normal adsorbent? Please discuss some socio economic scenario for heavy metal adsorption.

Dear Colleagues,

In recent years, carbon-based nanomaterials, such as graphene, carbon nanotubes, fullerenes, etc., have gained tremendous interest and more and more applications reap their numerous benefits. Lately, carbon nanodots (CNDs) have emerged as a new class of carbon-based nanomaterials, which have "outshined" other carbon-based nanomaterials, as they possess a unique combination of outstanding, enthralling and favorable properties for many applications. They are the sole carbon nanomaterials with inherent photoluminescence whereby multitudinous applications have been developed. They have been utilized as probes for analytical or biological applications, bioimaging agents for live cell and animal imaging purposes, drug carriers, photosensitizers in photodynamic therapy as well as in photocatalysis, solar cells, optronics, etc. The CNDs have come into their own as a standalone research field but their full potential is yet to be unraveled and harnessed. To understand their properties and gain deep knowledge on the subject, concise reviews and state-of-the-art research articles are needed.

In this context, we launched a Special Issue of C—Journal of Carbon Research, “Recent Advances in Carbon Dots” (https://www.mdpi.com/journal/carbon/special_issues/carbon_dots#published) , which is dedicated to the advancement of this novel field. We invite authors to submit original research articles, communications and reviews, related to all advances in the field of CNDs.

Contact me for further details.

An interesting paper from Novoselov lab titled "The Worldwide Graphene Flake Production" [doi.org/10.1002/adma.20180378] wherein they analyzed so-called "graphene" sold by over 60 companies and found that most, if not all are sub-standard. One damning observation is "...and no company is currently producing above 50% graphene content".

Since graphene discovered (2004) later then CNTs (1991) it surpassed the CNTs in respect of many properties like adsorption and chemical catalysis due to high surface area available in case of graphene:

but still today widely used CNTs as electrocatalyst and anode material in lithium ion batteries why?

so some broader views and comments are required from senior researchers and colleagues in the field of carbon nanomaterial please.

Thanks in advance

Please see the attached HRTEM and corresponding FFT images of my CNW / VGN sample. I am getting an interlayer spacing of 0.22 nm from ImageJ while strongest spots in FFT gives me 0.33 nm/Cycles.

I know that I should get 0.33 -0.34 nm interlayer spacing for graphene. I do not understand this anomaly.

I have been told that this is not Moire Fringe as dimension of my interlayer spacing is less than actual interplanar spacing of graphene i.e. 0.33 nm.

how can i reduce graphene oxide using sodium

borohydride and hdyrazine and is there a simple method for reduction

I'm investigating FET sensors and I don't have a good understanding of what differentiates traditional MOS FETs from new materials such as OFETs, CNT-FETs and Graphene-FETs. There's always so much hype about new materials, that I need an objective review paper to compare the properties of each class of FETs.

Any recommendations would be greatly appreciated. Thanks!

The carbon nanomaterial, we synthesized, is insoluble in most of the solvents. It forms suspension when dissolved. How can I quantify dispersion or how to determine the degree of dispersion in different solvents?

The coin of the GCE has came out so I want to know to whether it is possible to fix it back. If yes then how.

What are the current and more advanced production methods for nanocomposites (carbon nanomaterials or metal-carbon nanocomposites)?

How close are functional nanocomposites to industry?

I am developing a Lateral Flow Assay and need to block a nitrocellulose membrane with BSA for my initial sample test. How do I appropriately coat my membrane with BSA to avoid non-specific binding? I am using 10% BSA. The antibodies and antigens are very low in molecular weight (20-30 kDA). I will also be diluting the antigen/protein that I will be testing for in water. One of my sample tests will also contain neutravidin immobilized on the membrane for my test line and an anti-rabbit goat antibody on my control line. My conjugate will also consist of carbon nanoparticles and an antibody (low weight). On the other sample test, I will be immobilizing an antigen on the test line and the same secondary antibody as the other sample test on my control line. The conjugate remains unchanged. 

when we have nanoparticles in a polymeric solvent and it is not moving (hydrostatic), should we consider inertia for the particles negligible vs viscose forces? - and how would that be in case of using an external force field like magnetic or electric

Do Lennard Jones parameters ε and σ varies with the hybridisation of carbon.

I could find the lennard jones parameters for carbon atom in graphene. Will the values be same for carbon carbon interaction when carbon is in sp and sp3 hybridized states. Thanking you in advance

I got cylindrical bamboo structure in SEM ,but could not able to distinguish CNT or CNF ?

I am trying to make Carbon black/PDMS nanocomsite for piezoresister. However, ever after using upto 15% carbon black, I could not get conductivity. I dont walk to increase concentration further as it will make device very stiff than what I want.Can any suggest on this?

If add 20% of Silver nanoparticles, Carbon Black, Graphene or CNTs to uncured polymer and let it polymerize which of all this would increase the stiffnss or young's modulus of compsite as compared to pure polymer.

i need to explain the XRD plot for pure Carbon nano fiber and polymer nano composite with CNF at different loading.

I'm looking for the suitable sonication power to exfoliate expanded graphite in various solvents. What might happen if we use very high sonication power? Will it affect the quality and the size of the graphene?

I recently performed a two step purification of some single wall carbon nanotubes. 

First step involved refluxing 100mg of CNTs in 3M HCl for 2 days, which appeared to work effectively. They were dried and stored.

The next stage involved refluxing in a HNO3 (70%) and H2SO4 (95%), (3:1) solution for 4 hours. 

I noticed after the second reflux that all the nanotubes/ flakes had vanished, though I assume they had deteriorated into solution.

Can anyone support my hypothesis or explain, briefly, where I have gone wrong? I'm assuming reflux was too high.

Regards.

My ultrasonic bath sonicator has been corrupted and I want to replace it  with a stirrer system for chemically functionalization of MWCNTs in a mixture of sulfuric acid and nitric acid . Is it really effective on final result?

Thanks in advance

Hello,

I'm trying to find a method to measure the carbon black concentration in hexane to determine the rejection rate of a test membrane for my research project. Could anyone suggest a possible option/options to determine the carbon black concentration? Thanks for the help!

I'm measuring 250 micrometer thick film of exfoliated graphite. With zero applied current I get 22 mV tensions (it's still going up 0.01 mV/sec) and even negative tensions (it has gone to -8 mV) in Forward mode with a similar sample. What the hell is happening? Someone?

How to confirm the two-dimensional (2D) heterostructured composites? Apart from the SEM, TEM and EDX, which technique is more suitable to confirm the heterostructured composite?

I have prepared carbon dots derived from plant materials by hydrothermal method( A known weight of the plant sample was washed and grinded to paste and diluted with water prior heating). Following the different purification steps such as centrifugation, filtration and dialysis (using 2.5 kDa activated dialysis membrane) carried out for more than two days, I got clear solution. But after keeping it for one or two days the solutions would be not clear. If I use the same sample solution after filtering again the Fluorescence intensity would be decreased further.

is graphite nanoplatelets and graphene nano platelets same thing or are different ..........

I am currently trying to disperse GNPs in isoparaffin using an ultrasonic bath which disperse well but will being to settle out in <2 hours. Is there any way to achieve a stable dispersion in this type of fluid?

Any idea about what type of macro-structure for the carbon paste (mixture of graphite, carbon black, carrier polymer (binder)), which has a best performance in terms of conductivity.

I want to know, what is the best way to decorate the smallest size of Polyaniline on graphene quantum dots?

best regards

please anyone help me to clean Glassy carbon electrode 

modified with AuNPs . 

how to remove AuNPs from Glassy carbon  electrode surface

and also from sides of electrode

I need to determine the RATIO OF the amount of disordered/amorphous/damaged structure of carbon TO well graphitized carbon nanotubes present in the sample.

Originally posted description of the question as on May 9, 2017 is given below.

Updated on September 28, 2020

:) Thanks for all responses and looking forward to more discussion!!

Hello

Dear All

I am wondering if we can use TEM analysis as a direct evidence to know about the quality of a dispersion for example in case of graphene or carbon nanotube dispersion.

Raman analysis of Reduced graphene oxide

I will make an electrodes of MnO₂. For make the paste I need to mix the MnO2 with PVDF and Carbon Black into a slurry of N-Methyl-2-pyrrolidone. But get the solvent is difficult, because it is scarce. I want to know what is a universal solvent than I can use in your replacement?

As is told in a lot of paper, CNTs don't provide good dispersion on the many solvents while I need to corporate CNTs on the carbon felt to use as electrode. How to decorate carbon felt using CNTs as CNTs don't really dispersed well and I end up decorated only the surface of the carbon felt. Is any binder needed? I tried with nafion but end up getting lower result compared to bare felt. Thanks in advance

Water is useful to dispersion or any other solvent needed?

I have synthesized RGO/ZnO/Cu composite and did Raman of that. I have got mainly 2 high intensity peaks. One is around 450 and another is around 1090cm-1. From the literature I came to know that 450cm-1 peak is of ZnO. But I'm confuse about the peak at 1090cm-1. D and G band of Graphene are around 1300 and 1500cm-1 respectively. Then why I'm getting only one peak at 1090?

Please go through the reference paper for details.

Carbon black is used as electrode.