Construction of MoO2 Quantum Dot-Graphene and MoS2 Nanoparticle-Graphene Nanoarchitectures toward Ultrahigh Lithium Storage Capability.

Herein, MoO2 quantum dots (QDs; <5 nm) are synthesized through a one-step solvothermal process. MoO2 QD-bonded graphene sheets (MoO2-QDs@RGO) are facilely produced and can be further converted through sulfidation into MoS2 nanoparticle-bonded graphene sheets (MoS2-NPs@RGO). The novel MoO2-QDs@RGO electrodes demonstrate exceptionally attractive lithium storage capability (e.g., 1257 mA h g-1 at 100 mA g-1, being close to the highest values ever reported for a MoO2-based lithium ion battery electrode), rate capability, and cycle stability. Moreover, the MoS2-NPs@RGO delivered a superior capacity (1497 mA h g-1 at 100 mA g-1) with outstanding rate retention and cycling stability. The superior lithium storage capabilities are ascribed to the synergetic effects of the high-surface-area graphene sheets, the well-dispersed MoS2 nanoparticles, and their strong bonding with each other, which effectively prevents aggregation of MoS2 while the composite architecture allows fast transport of electrons and ions.