NANOSYSTEMS: PHYSICS, CHEMISTRY, MATHEMATICS, 2014, 5 (2), P. 294–306
SYNTHESIS OF GRAPHENE NANOPLATELETS FROM PEROXOSULFATE GRAPHITE INTERCALATION COMPOUNDS
A. V. Melezhyk – Tambov State Technical University, Tambov, Russia; firstname.lastname@example.org
A. G. Tkachev – Tambov State Technical University, Tambov, Russia; email@example.com
Ultrasonic exfoliation of expanded graphite compound obtained by cold expansion of graphite intercalated with peroxodisulfuric acid was shown to allow the creation of graphene nanoplatelets with thickness of about 5-10 nm. The resulting graphene material contained surface oxide groups. The expanded graphite intercalation compound was exfoliated by ultrasound much easier than thermally expanded graphite. A mechanism for the cleavage of graphite to graphene nanoplatelets is proposed. It includes: (1) formation of ionic graphite compound intercalated with peroxodisulfate anions; (2) decomposition of intercalated peroxodisulfate anions with formation of active free radicals which (3) attach covalently to carbon atoms; (4) cleavage and expansion of the graphite crystal due to the thickening of the peripheral region of graphene layers and release of gaseous oxygen between graphene layers; (5) hydrolysis of the expanded graphite compound; and, finally, (6) ultrasonic breaking of graphene nanoplatelet agglomerates.
Keywords: graphene, graphene nanoplatelets, peroxodisulfuric acid, graphite intercalation compounds, cold expansion.
PACS 81.07.-b, 81.05.ue