Silicon-doped graphene nanoflakes with tunable structure: Flexible pyrolytic synthesis and application for lithium-ion batteries

Incorporation of heteroatoms into graphene layers is a powerful way of tuning their surface and structure. We developed for the first time a tunable approach for the synthesis of Si-doped jellyfish-like graphene nanoflakes (Si-GNFs) via template pyrolysis. The synthesis parameters were shown to affect the doping level, silicon bonding type, heteroatom localization in Si-GNFs, and the defectiveness of the synthesized material. The silicon incorporation into GNF layers creates acidic and basic Lewis sites as it was tested in the butanol-2 conversion over Si-GNF. Doping of GNFs with Si significantly boosted the specific capacity of GNF-based electrode of the lithium-ion battery up to 600 mAh*g−1. The capacity enhancement was ascribed to the redistribution of the electron density due to the difference in electronegativity between C and Si, corrugation of the graphene layers by heteroatoms, and reduction of silicon species. The synthesis conditions were shown to strongly affect the capacity and cycle stability of the electrode.