I subjected the recrystallized urea + thiourea solids in a alumina crucible and covered with two layers of foil paper and subjected to 500 degrees Celsius at a rate of 3 degrees Celsius/min to obtain g-C3N4. I had to stop the reaction in the proceeding when little pop like sounds was being heard. After cooling I found the crucible was terribly damaged. I have had done the experiment before and I found desirable result but this time such setbacks are being encountered. Kindly provide me with probable reasons for such setbacks and if possible suggest me other ways to obtain gC3N4 with simple steps alike thermal polymerization of urea and thiourea.
Good morning. In my work I used a porcelain crucible covered with a lid made of the same material.
Hi Eliane... Thank you for responding... So you suggest using porcelain crucible? But alumina crucible can withstand a temperature over 1500℃.. so I'm a little confused...
I used porcelain crucibles to guarantee the absence of possible residues and the large number of publications that use this crucible.
Dear Sudarshan, many thanks for your interesting and rather unusual technical question. Of course it is very difficult (if not impossible) to judge why your alumina crucible broke during your attempted g-C3N4 synthesis. I actually did not find any other related case in the literature. One suggestion from my side would be that the crucible was contaminated with some other chemicals prior to your experiment. An indication for this might be the brown spots shown in your first picture. Perhaps the alumina crucible was already damaged before the heating.
In order to avoid this in future experiments I would suggest to use a clean new crucible. In general, alumina crucibles should be suitable for this synthesis. As an interesting alternative you might also consider the use of melamine as starting material for the preparation of g-C3N4. This is described in detail in the following useful article in which a simple high-yield synthesis of g-C3N4 for enhanced visible light photocatalytic activity is reported. The authors of this paper also use alumina crucibles conered with aluminum foil. I think it's important to exactly follow the heating and cooling rates described in this study:
One-step, high-yield synthesis of g-C3N4 nanosheets for enhanced visible light photocatalytic activity
https://pubs.rsc.org/ko/content/articlepdf/2019/ra/c9ra08922e
You can also easily find and access relevant papers on this topic by using the "Search" function of RG. For example, look for the term "g-C3N4 synthesis" and then click on "Publications":
https://www.researchgate.net/search.Search.html?type=publication&query=g-C3N4%20synthesis
Numerous papers on this topic have been posted on RG, some of them even as public full texts.
Good luck with your research and please stay safe and healthy! 👍
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