3D Graphene foam from glucose by chemical blowing

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Discussion Overview

The discussion revolves around the synthesis of 3D graphene foam from glucose using chemical blowing methods. Participants explore various techniques, particularly focusing on the use of hydrothermal methods and the specific process outlined in a research article involving glucose and ammonium salts. The conversation includes technical questions about the synthesis process, temperature conditions, and the materials involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant shares their background and expresses interest in synthesizing 3D graphene foam without high costs, referencing various methods and articles.
  • Questions are raised about the specific conditions for using argon gas in the synthesis process, including the required pressure and whether a tube furnace is necessary.
  • Clarification is provided that the glucose and ammonium salt should be mixed in solid form in a 1:1 weight ratio.
  • Participants discuss the temperature profile for the synthesis, noting that the conversion of glucose to melanoidin and then to graphene is described as a one-step process, although the exact mechanisms remain unclear.
  • Concerns are raised about the potential for caramelization of glucose at certain temperatures and whether it is possible to achieve a white foam product.
  • Another participant mentions limitations in heating equipment that may restrict the maximum achievable temperature during synthesis.
  • A suggestion is made to review Dr. Wang's recent papers for further insights into optimizing the synthesis process.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and uncertainty regarding the synthesis process, with no consensus reached on specific procedural details or outcomes. Some participants provide clarifications, while others pose additional questions that remain unresolved.

Contextual Notes

Limitations include uncertainties about the exact conditions for the synthesis process, such as the necessity of a tube furnace versus other types, the implications of temperature variations, and the potential outcomes of using different heating rates.

Who May Find This Useful

This discussion may be of interest to undergraduate students in physics or materials science, researchers exploring graphene synthesis methods, and individuals looking to understand the chemical processes involved in creating advanced materials.

trujafar
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I'm a third year physics undergraduate and I want to make 3D Graphene - without spending a fortune.

This is my background:

I found this review article by Jiang and Fan (Design of advanced porous graphene materials: from graphene nanomesh to 3D architectures) to be very helpful. From what I've understood, the main methods are hydrothermal and CVD. CVD involves using nickel foam, and at $250 a sheet Marketech Intl, Inc. - Nickel Foam is a no-no. However, hydrothermal methods such as this one Porous 3D graphene-based bulk materials with exceptional high surface area and excellent conductivity for supercapacitors which use graphene oxide and surcose seems more promising.

In line with this, I've done research on graphene oxide (a precurser to many graphene-based products), and have read about the Hummer's method, the Improved Hummer's Method (http://pubs.acs.org/doi/abs/10.1021/nn1006368) and have also watched Robert Murray-Smith's videos (www.youtube.com/user/RobertMurraySmit[/URL]).

Now for my question:

I read this article [URL="http://www.nature.com/ncomms/2013/131216/ncomms3905/full/ncomms3905.html"]Three-dimensional strutted graphene grown by substrate-free sugar blowing for high-power-density supercapacitors[/URL] which has a seemingly simple and interesting method for synthesis of 3D graphene foam, which I would very much like to make. But upon reading the article, I'm facing a couple of problems:

1) In the Methods section of the paper use argon gas is used for the ambient gas in the tube furnace. Under what pressure does this take place? Does it have to be a tube furnace, or will any other furnace with programmable temperature work?

2) Is the glucose mixed directly with amonnium salt, or is it dispersed in a solution?

3) In the diagram, glucose is converted to meldonin at ~250C, then it is heated to ~1350C. Is the melanoidin conversion carried out in ambient conditions, and then the sample cooled to room temprature, or is this a one step process? What exactly happens? Can I carry this out in lower temprature, say ~ 900C at the cost of lower quality?

[URL]http://www.nature.com/ncomms/2013/131216/ncomms3905/images/ncomms3905-f4.jpg

I've sent a email to Dr Yoshio Bando a couple of days ago, but I haven't yet got an answer. I'm worried that I wasn't very polite.
 
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I'm sorry you are not generating any responses at the moment. Is there any additional information you can share with us? Any new findings?
 
trujafar said:
1) In the Methods section of the paper use argon gas is used for the ambient gas in the tube furnace. Under what pressure does this take place? Does it have to be a tube furnace, or will any other furnace with programmable temperature work?

The pressure is 1 atm. There is nothing special about a tube furnace, but the fact that it is easy to create a specified atmosphere. This is really important since for the pyrolosis of carbon to take place, an inert gas is needed, otherwise the glucose will burn. According to their paper, 4C/min is the optimal temprature ramp for strutted graphene production.


trujafar said:
2) Is the glucose mixed directly with amonnium salt, or is it dispersed in a solution?

Both are in solid form, and the solid white glucose powder is directly mixed with the amonnium salt in a 1:1 ratio in weight.

trujafar said:
3) In the diagram, glucose is converted to meldonin at ~250C, then it is heated to ~1350C. Is the melanoidin conversion carried out in ambient conditions, and then the sample cooled to room temprature, or is this a one step process? What exactly happens? Can I carry this out in lower temprature, say ~ 900C at the cost of lower quality?

The shown diagram states that in the while it is being heated to 1350C, glucose is converted to meladonin, and then graphene. However, as far as the experimental procedure needs to cencern itself, it is a one-step process. What exactly happens is not known. At a lower temprature, to quote directly from Dr Wang "will be something similar to strutted graphene, just with a lower crystalline degree, lower conductance and lower specific surface area."

My understanding of the above is thanks to Dr Xuebin Wang. Any errors are due to misunderstanding on my part.
 
so regarding 2), do you mix glucose and ammonium salts in solid form and bring them to 200 deg 4deg/min to form the foam, and that is done at room atmosphere?
Would you get a brown "caramel" foam or a white glucose form? at around 160 deg glucose start caramelizing.

any recipes to get white glucose foams?
 
The synthesis of the grapheme foam is a one-step process from room temperature to 1350C with a temperature step of about 5C/min.
It is important that it is performed in a inert atmosphere. A tube furnace is generally used for these purposes.
However, the heating element, tube material and thermocouple will limit the maximum temperature that you can go up to. Due to these limitations, I was only able to go up to 1000C. Below is the sample.
Graphene Sample.jpg
 

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I'd suggest that you would take a look at Dr Wang's recent papers. He has further optimized and examined the bubbling process. Of particular interest is his paper titled "High-throughput fabrication of strutted graphene by ammonium-assisted chemical blowing for high-performance supercapacitors". Study the section titled "Growth process of ammonium-assisted chemical blowing for SG". It will give you a greater insight into the process.
 

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