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