Mo Ion Intercalation-Driven Exfoliation of Bismuth Selenide Into Nanosheets Enriched With Molybdenum Selenide Enables Electronic Structure Regulation for Advanced Zinc Storage Cathode.

As a representative topological insulator, Bi2Se3 adopts a trigonal structure and demonstrates attractive energy storage properties in aqueous zinc-ion batteries (AZIBs) due to the creation of Dirac surface states. However, the strong van der Waals forces and absence of dangling bonds between layers cause the thermodynamically stable bulk to retain stacked structures with limited active surfaces and interfaces, resulting in a high energy barrier and poor energy storage dynamics. Herein, pre-intercalated molybdenum ions induce the in situ formation of MoSe2 nanodots, which serve as interlamellar pillars to exfoliate bulk Bi2Se3 into ∼4 nm flakes. This process simultaneously increases the surface-to-bulk ratio and regulates the electronic structure of Bi2Se3, thereby boosting its zinc storage performance. The material's reaction mechanism as the cathode for AZIBs and its phase and structural evolutions during the charging-discharging process are clarified via a combined ex- and in situ analysis. The impacts of MoSe2 on the structure, electronic state, charge transfer, ion adsorption behavior, and diffusion barrier of Bi2Se3 are studied by an integrated experimental investigation and theoretical calculation. This work develops an intercalation-exfoliation strategy to thin the layered topological insulator while integrating heterointerface construction, demonstrating the feasibility of synthesizing thin-layer Bi2Se3-based materials for high-performance cathodes in energy storage.