Boosting Na⁺ Storage Ability of Bimetallic Mo_x W_1-x Se₂ with Expanded Interlayers

In spite of the valuable advancements in the fabrication of transition-metal selenides (TMSs)-based hybrid structures, only single-metal selenides have been obtained through most of the present methods. Herein, a facile room-temperature self-polymerization and subsequent selenization strategy is proposed for the synthesis of bimetallic Mo_x W_1-x Se₂ nanosheets with expanded interlayers decorated with N-doped carbon-matrix assembled flowerlike hierarchical microspheres (Mo_x W_1-x Se₂ /NC). Depending on the excellent coordination ability of dopamine with metal ions, self-formed flowerlike single precursors are harvested. The unique hybrid architecture benefits the penetration of the electrolyte, accelerates Na⁺ insertion/extraction kinetics, enhances electron-transfer ability, and alleviates the volume expansion and aggregation during cycling processes. Therefore, the bimetallic Mo_x W_1-x Se₂ /NC electrode delivers high reversible capacities of 264 mA h g^-1 at 1 A g^-1 for 700 cycles, 204.4 mA h g^-1 at 4 A g^-1 for 1400 cycles, and 153.3 mA h g^-1 at 8 A g^-1 for 2000 cycles, as well as an excellent rate capability up to 10 A g^-1 with a capacity of 188.9 mA h g^-1 . Our study offers an effective strategy to boost sodium storage performance through elaborate structural engineering.