Construction of MoO 2 Quantum Dot-Graphene and MoS 2 Nanoparticle-Graphene Nanoarchitectures toward Ultrahigh Lithium Storage Capability.

Herein, MoO ₂ quantum dots (QDs; <5 nm) are synthesized through a one-step solvothermal process. MoO ₂ QD-bonded graphene sheets (MoO ₂ -QDs@RGO) are facilely produced and can be further converted through sulfidation into MoS ₂ nanoparticle-bonded graphene sheets (MoS ₂ -NPs@RGO). The novel MoO ₂ -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 MoO ₂ -based lithium ion battery electrode), rate capability, and cycle stability. Moreover, the MoS ₂ -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 MoS ₂ nanoparticles, and their strong bonding with each other, which effectively prevents aggregation of MoS ₂ while the composite architecture allows fast transport of electrons and ions.