Hierarchical MOF-derived layered Fe3O4 QDs@C imbedded on graphene sheets as a high-performance anode for Lithium-ion storage

Herein, a double-buffering strategy is presented to boost the lithium storage potential of Fe3O4. Firstly, the skeleton of MIL-100 (Fe) MOF is grown on graphene oxide, as a self-assembled template via in-situ solvothermal approach, which transform into ultrafine, well-dispersed and mesoporous carbon coated Fe3O4 QDs (4 nm) imbedded on reduced graphene oxide (Fe3O4 QDs@C/rG0), by pyrolysis. Each component in such a well-designed porous hierarchical structure significantly contributes to the remarkable enhancement of lithium ion storage performance, leading to high reversible capability with excellent prolonged cyclic stability after 2000 cycles (505 mAh g(-1) at 2.0 A g(-1)). Both, Graphene sheets and mesoporous carbon act as conductive support for anchoring uniform Fe3O4 QDs with confined double buffering for cyclic volume flux. Multi-channels with uniform mesopores in the self-assembled array and 4 nm QDs of Fe3O4 confined in conductive carbon shells were favorable to enhance the interfacial electron/ion transfer, leading to the excellent rate and cycling performance with released volume changes upon Li+ insertion/extraction. The present research work provides a promising outset design and synthesis strategies for metal oxide QDs based nanocomposites, which may also be extended to the other electrode material system.