Continuous and catalyst free synthesis of graphene sheets in thermal plasma jet

- Plasma processing of alcohols yields graphene sheets and carbon particles.
- Graphene sheets are selectively synthesized from ethanol only.
- Graphene sheets are continuously produced with the production rate 1.5 g·h−1.
- Oxygen to carbon ratio is the key parameter which drives process selectivity.

Herein we present a continuous and catalyst free method for the synthesis of graphene sheets from aliphatic alcohols in a radiofrequency thermal plasma jet. Nine aliphatic linear alcohols (ethanol-decanol) were tested as possible precursors for the massive production of graphene sheets. Moreover, additional tests were also carried out with the inclusion of gaseous oxygen in order to promote the formation of graphene and to eliminate the unwanted carbon byproducts. The obtained materials were investigated by electron microscopy, Raman and infrared spectroscopy. The thermal stability of products was also evaluated using thermogravimetry. The surface chemistry features were analyzed using acid-base titration and X-ray photoelectron and IR spectroscopy. Finally, the adsorption performance of graphene sheets was tested in the removal of 4-chlorophenol from aqueous solutions. The highest content of graphene sheets was found in the product obtained from ethanol with the production rate of ca. 1.5 g/h. The plasma processing of higher alcohols yielded a mixture of graphene sheets and spherical carbon nanoparticles.

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