Bilayer-favored intercalation induced efficient and selective liquid phase production of bilayer graphene

Abstract

Bilayer graphene (BLG) is gaining increasing attention as one of the most promising candidate materials for post-silicon nanoelectronics. It is still a tremendous challenge to selectively and efficiently produce BLG at low cost and under mild conditions. Herein, a novel strategy of bilayer-favored intercalation (BFI) induced liquid phase exfoliation of BLG under mild conditions was developed. This simple approach can effectively exfoliate graphite to give BLG with a high yield of 52.3%, and selectivity as high as 86.5%. The obtained twisted BLG not only maintains the structural integrity and low surface oxidation of graphene, but also demonstrates great electron mobility. With careful experimental design and use of DFT calculations, such efficient production of BLG is proved to originate from the formation of a stage-two graphite intercalation compound via the bilayer-favored intercalation of chromyl chloride (CrO₂Cl₂) into graphite flakes driven by the electrostatic interactions between CrO₂Cl₂ and graphene sheets. The BFI-induced liquid phase exfoliation strategy shows great potential for the industrial scale production of high-quality BLG.