Exfoliation of graphite by pyrolysis of bromine–graphite intercalation compounds in a vacuum glass tube

Graphite intercalation compounds (GICs) of bromine were rapidly heat-treated and exfoliated at 500 °C in vacuum to obtain oxygen-free exfoliated graphite materials. We developed a continuous process—from intercalation to exfoliation—that could be conducted in a single glass tube without exposure to air so as to obtain oxygen-free exfoliated graphite products. It was possible to repeat the process of intercalation and exfoliation several times using bromine, which enabled large-scale exfoliation of graphite at 500 °C—comparable to that obtained from GICs produced from sulfuric acid.

► Graphite is exfoliated in vacuumed glass tube even at low temperature, 500 °C, under oxygen-free situation. ► Succeeded a continuous process from synthesis of GIC to exfoliation in same one glass tube. ► Also succeeded a repeat process of intercalation and exfoliation to exfoliate graphite as much as possible. ► Exfoliation degree, structure, and morphology were compared with typical exfoliation using sulfuric acid.