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.