Hierarchical Tubular-Structured MoSe2 Nanosheets/N-Doped Carbon Nanocomposite with Enhanced Sodium Storage Properties.

Abstract

Intimately coupled carbon/molybdenum-based hierarchical nanostructures are promising anodes for high-performance sodium-ion batteries owing to the combined effects of the two components and their robust structural stability. Mo-polydopamine (PDA) complexes are appealing precursors for the preparation of various Mo-based nanostructures containing N-doped carbon (NC). A facile method for the fabrication of hierarchical tubular nanocomposites with intimately coupled MoSe2 and NC nanosheets has been developed, which involves the preparation of Mo-PDA hybrid nanotubes through a chemical route followed by two heat treatments. The strong coupling between Mo anions and the catechol groups in dopamine not only restricts the crystallite size but also inhibits agglomeration during selenization, resulting in few-layered MoSe2 nanosheets embedded in hierarchical NC substrates. The as-synthesized nanotube composites are constructed by assembling primary MoSe2 /NC nanosheets. This unique structure not only increases the number of active sites but also shortens the diffusion length of ions and enhances the electronic conductivity of electrode materials. The as-synthesized hierarchical MoSe2 /NC nanotubes deliver a high capacity of 429 mAh g-1 at 1 A g-1 after the 150th cycle when used as anodes in sodium-ion batteries. Furthermore, at a high current density of 10 A g-1 , a high discharge capacity of 236 mAh g-1 is achieved.