I read an article (https://doi.org/10.1016/j.synthmet.2020.116364) regarding the direct conversion of anthracite into graphene in the presence of molten.

I would like to ask the view from experts regarding the modified methodology.

The authors described the methodology in the paper as follows.

1. Carbon black is first grinded into powder of about 500 mesh.

2. Before using, iron powder (purity, 98 %; size, 400 mesh) is washed with diluted hydrochloric acid (HCl) to remove quickly the iron oxide layer. Then carbon black mixed with iron in the ratio of 1:5 or 1:10 in weight.

3. The mixture is then transferred into corundum crucibles and calcined in a tube furnace at 1600°C for 6 h under a 0.3 L/min argon flow. Heating and cooling rate are set to 10 °C/min. 4. After cooling to room temperature, the calcined mixture is corroded in excessive 1-M HCl for 48 h followed by washing with DI water three times.

5. The solid product is dried for 24 h at 110°C in vacuum oven.

My questions are

(a)Can we reduce the synthesis temperature from 1600°C to lower temperature by using other metal powder?

(b) What is the role of argon in the production of graphene?

(c) Can we still produce graphene using this method if we only use chamber furnace without argon gas supply?

I need the views/opinions from experts.