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Author: Subject: Easy Colourful Quantum Dots
Housane
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[*] posted on 17-6-2020 at 14:17
Easy Colourful Quantum Dots


Today I managed to make green carbon quantum dots by dissolving 3g of sucrose in 10ml of water and 1ml of 30% HCl was added to make it acidic. It was then heated at 80-90C for 10 minutes and the water was allowed to evaporate. After 5 mins the solution turned yellow and it got steadily darker. After the 10 mins a distinctly sweet our could be smelt.

It was take off the heat and allowed to cool. The remaining black solution was dissolved in 150ml of water and then filtered, a dark filtrate was collected. This was made neutral by addition of NaOH. These are quantum dots but to see them clearly i diluted them. In the pictures the range on the lower level is 2 fully concentrated then 5 vials going from 25% to 5% in 5% increments. Feel free to ask any questions. The glow is poor as the light is a cheap UV invisible ink pen, I will do better pictures on request.

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Housane

IMG_20200617_225715.jpg - 396kB IMG_20200617_225736.jpg - 263kB IMG_20200617_225703.jpg - 518kB

[Edited on 18-6-2020 by Housane]




Green QD's so far

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Housane
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[*] posted on 17-6-2020 at 14:21
More pictures




IMG_20200617_225748.jpg - 330kB IMG_20200617_225753.jpg - 402kB IMG_20200617_225820.jpg - 2MB




Green QD's so far

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Ubya
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[*] posted on 17-6-2020 at 17:26


i have a request for you, could you check in a few months/a year if they still fluoresce the same?
i made some blue quantum dots via the hydrothermal method (pretty much the same thing you did but in a closed vessel and at 180°C instead of 90) a year and a half ago, and now the solution fluoresces green and it is much much fainter, i suspect that with time the nano particles aggregate somewhat, i would be interested to know how long it takes for yours





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Housane
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[*] posted on 18-6-2020 at 00:05


Yeah sure,I will do an update in a year or so



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draculic acid69
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[*] posted on 18-6-2020 at 03:00


This sounds a lot like making levulinic acid.
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mackolol
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[*] posted on 18-6-2020 at 04:07


And what's the chemistry behind it. What chemical is formed by heating sugar with HCl and then neutralising it?
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Housane
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[*] posted on 18-6-2020 at 05:14


The idea is you are breaking down the carbon and then slowly reforming it in such a way that lots of tiny particles are formed and this is what changes the colour of the UV light. Thought emporium has a video about them. The acid slightly alters this. Others colours should be possible in Basic solutions and the colour may change depending on what acid is used, more exeprimatation I need to do



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Housane
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[*] posted on 18-6-2020 at 13:13


I think I have just made yellow quantum dots, I will post again when the solution is concentrated enough to get a good picture



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wg48temp9
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[*] posted on 14-8-2020 at 14:21


While looking for a wiring diagram for my dishwasher, which I did not find, but I did find a paper describing how to make Doped/Co-Doped Carbon Quantum Dots. I thought others may find it useful so I am posting it in this thread.

Attachment: carbon-05-00024-v2.pdf (5.1MB)
This file has been downloaded 107 times




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Housane
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[*] posted on 11-10-2020 at 06:58


Ubya, I have just checked them and both the green and the yellow glow exactly the same as before



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