Hierarchical MoS₂ Hollow Architectures with Abundant Mo Vacancies for Efficient Sodium Storage

Achieving a molecular level understanding of surface performance of nanomaterials by modulating the electronic structure is important but challenging. Here, we have developed a hollow microcube framework constructed by Mo-defect-rich ultrathin MoS₂ nanosheets (HMF-MoS₂) through a zeolite-like-framework-engaged strategy. The hollow structured HMF-MoS₂ delivers an impressive specific capacity (384.3 mA h g^-1 after 100 cycles at 100 mA g^-1) and cycle stability (267 mA h g^-1 after 125 cycles at 1 A g^-1) for sodium storage. As evidenced by experiments and density functional theory calculations, abundant Mo vacancies in MoS₂ can greatly accelerate the charge transfer and enhance the interaction between MoS₂ and sodium, resulting in the promotion of sodium storage. Kinetic analysis result reveals that the ultrafast sodium ion storage of HMF-MoS₂ could be associated with the significant contribution of capacitive energy storage. This work highlights the detailed molecular level understanding of chemical reaction on MoS₂ surface by defect and morphology engineering, which can be applied to other metal sulfides for energy storage devices.