in 2015, Peng et al (DOI: 10.1038/ncomms6716) reported a scalable and green method to produce graphene oxide, using potassium ferrate (K2FeO4) as strong oxidant instead of KMnO4:
"K2FeO4 (60 g, 6 wt equiv.) was added to concentrated H2SO4 (93%, 400 ml) at room temperature. Graphite (10 g, 1 wt equiv.) was then added and the mixture was kept at room temperature for 1 h..." then the precipitate was purified and dried to get GO.
However, in 2016, Sofet et al (DOI: 10.1002/anie.201603496) published an article entitled "Synthesis of Graphene Oxide by Oxidation of Graphite with
Ferrate(VI) Compounds: Myth or Reality?" where they claimed that they critically replicated the method reported by Peng et al, and confirmed the unsuitability of using ferrate(VI) for the oxidation of graphite on graphene oxide because of its high instability in an acidic environment.
After reading these articles, which one do you find is right?
Note: in the supporting info of the second articles, it seems that they did not 100% replicate Peng method:
"For the oxidation of graphite, we used the method reported by Peng et al. [3] An ice bath was used to cool 40 mL of 93 wt.% H2SO4 to below 20 °C. Then, 10 g of K2FeO4 was added to the sulphuric acid over a period of ten minutes while the solution was intensively stirred. The dissolution of K2FeO4 was extremely violent and it should be noted that the use of potassium ferrate(VI) containing potassium hydroxide can be explosive. The violent evolution of gas indicated the fast decomposition of potassium ferrate(VI). Subsequently, 1 g of graphite was added to the reaction mixture, which was then stirred for 1 hour and purged in 1 L of deionized water..." then the precipitate was purified and dried to get GO.
you noticed that they used at a temperature below 20 °C, they used lower quantity of H2SO4 and higher quantity of K2FeO4, furthermore they purged it in water which was not reported in Peng's article.
Noting also that in a quick research I didn't find another article where Peng method was used even in the new articles of Peng himself (maybe it exists but I did not find it).
Thank you for the article, but what about the ones I cited above? They used K2FeO4 in sulfuric acid not in water as the one u reported. The second article cited above said that "In practical terms, ferrate(VI) stability at room temperature is limited to two seconds in strongly acidic aqueous solutions" which means that there is a big contradiction between the reported results. which one do u think is right?
Dear Zineb,
Have You right. It is not clearly. Unfortunately I haven't been successful in replicating the K2FeO4+H2O2 composition, further research on the method for potassium ferrate Fe(VI) obtaining is needed. I'm not sure if I'll pursue this topic further.
best regards , Andrzej
Dear Prof. Andrzej Mianowski
Can you please tell us what are the problems you've faced when trying to replicate GO synthesis using K2FeO4+H2O2 in water? By the way did you synthesize K2FeO4? Because I read that it is not currently produced on an industrial scale.
Dear Zineb, I’m sending You the preparations of potassium ferrate. Unfortunately, I can’t find the source of this recipe, because I got this from my colleagues. Potassium ferrate is strongly stable in alkaline water (pH> 14) whereas it reduces water in acidic and neutral environment. Further proceedings acc. to the sent manuscript Yu_et_al-2016-Scientific_Reports.pdf Potassium ferrate is a commercial product. See: Metals 2015, 5, 1770-1787; doi:10.3390/met5041770 Table 1. Best regards, Andrzej
Dear Zineb, I’m sending You the preparations of potassium ferrate. Unfortunately, I can’t find the source of this recipe, because I got this from my colleagues. Potassium ferrate is strongly stable in alkaline water (pH> 14) whereas it reduces water in acidic and neutral environment. Further proceedings acc. to the sent manuscript Yu_et_al-2016-Scientific_Reports.pdf Potassium ferrate is a commercial product. See: Metals 2015, 5, 1770-1787; doi:10.3390/met5041770 Table 1. Best regards, Andrzej
Dear Zineb, I’m sending You the preparations of potassium ferrate. Unfortunately, I can’t find the source of this recipe, because I got this from my colleagues. Potassium ferrate is strongly stable in alkaline water (pH> 14) whereas it reduces water in acidic and neutral environment. Further proceedings acc. to the sent manuscript Yu_et_al-2016-Scientific_Reports.pdf Potassium ferrate is a commercial product. See: Metals 2015, 5, 1770-1787; doi:10.3390/met5041770 Table 1. Best regards, Andrzej Preparative Methods: NaOCl (20 g) is added to a solution of NaOH (30 g in 75 mL H2O) while keeping the solution temperature under 20 °C. Solid NaOH (70 g) is added with stirring, while maintaining the solution temperature at 25–30 °C, the solution cooled to 20 °C and filtered. Fe(NO3)3*9H2O (25 g) is added slowly, and the solution saturated with NaOH while being kept at 30 °C. After filtration, the filtrate of sodium ferrate is placed in a 20 °C bath and treated with saturated aqueous KOH (100 mL), stirred for 5 min, and filtered. The precipitate is washed several times with 10 mL portions of 3 M KOH into 50 mL of chilled saturated KOH solution, and a further 50 mL of chilled saturated KOH solution added to the washings. After stirring for 5 min, the solution is filtered, and the precipitate washed with benzene (10 mL) and several times with ethanol (20 mL). The precipitate is stirred with ethanol (1 L) for 20 min and the ethanol removed by filtration; this process is repeated three times. The precipitate is finally washed with (C2H5)2O under a drying tube, and drying continued in a vacuum desiccator.
Thank you very much dear professor
By the way I contacted prof. Chao Gao, the correspondent author of the first article cited above (Peng's method). Here was his answer:
"The problem lies in the commercial potassium ferrate mixed high content of other reagents, so it is difficult to repeat the reaction. Nevertheless, there are published reports following our work. Our technology has been transferred to a company, and now the GO had been produced in large scale.... www.gaoxitech.com "
I answered that in Sofet et al (2016) article, they claimed that they tried both laboratory-prepared and commercially supplied K2FeO4. So the purity of the materials they used was not enough maybe. How much was the purity of K2FeO4 you used? If you used the commercial one how did you process for its purification?
Here was his answer: " In that paper, we used commercial reagents. But we found that later different companies have quite different quality and concentration, even different batch has different quality."
So he didn't give a lot of details.
Dear Zineb, For my process, I used laboratory-prepared potassium ferrate (I send You the recipe). Unfortunately, I didn't mark the purity of K2FeO4 (after one month I used it which was a mistake). Best regards, Andrzej
waoo i am trying to do the same but obtaining K2FeO4 as results of other reactions and them mixing with H2SO4 by Ramaan spectroscopy is ok, but by XRD don't intercalate ... i will share soon if i get out with
this process Best Regards Jose
Dear Jose, I am waiting for further comments. I wonder if this is a sensible method of oxidation. Best regards
A. Mianowski
Dear Andrzej
i have problems with the intercalation & exfoliation ,it re-staked, but oxidate well as GO
when i solve this problem i will tell you
Best regard
until now continuous as oxidative graphite , i don't have how centrifuge like the original article
Dear all,
Did anyone here use Mössbauer spectroscopy to ascertain the purity of the obtained ferrates?
In case, you need that, do not hesitate to contact me.
Have a nice day.
Moulay
some one wrote about it
Synthesis of Graphene Oxide by Oxidation of Graphite with Ferrate(VI) Compounds: Myth or Reality?
Sofer Z1, Luxa J2, Jankovský O2, Sedmidubský D2, Bystroň T3, Pumera M4.
but i confirm that it oxidate but not intercalated i don't way to centrifuagted with this velocity ... but raman give me more or less 50% of oxide
Here is a good paper on the Mossbauer studies on ferrates :
https://link.springer.com/article/10.1007/s10751-008-9828-0
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