Heterostructured Bi₂S₃-Bi₂O₃ Nanosheets with a Built-In Electric Field for Improved Sodium Storage

Constructing novel heterostructures has great potential in tuning the physical/chemical properties of functional materials for electronics, catalysis, as well as energy conversion and storage. In this work, heterostructured Bi₂S₃-Bi₂O₃ nanosheets (BS-BO) have been prepared through an easy water-bath approach. The formation of such unique BS-BO heterostructures was achieved through a controllable thioacetamide-directed surfactant-assisted reaction process. Bi₂O₃ sheets and Bi₂S₃ sheets can be also prepared through simply modifying the synthetic recipe. When employed as the sodium-ion battery anode material, the resultant BS-BO displays a reversible capacity of ∼630 mA h g^-1 at 100 mA g^-1. In addition, the BS-BO demonstrates improved rate capability and enhanced cycle stability compared to its Bi₂O₃ sheets and Bi₂S₃ sheets counterparts. The improved electrochemical performance can be ascribed to the built-in electric field in the BS-BO heterostructure, which effectively facilitates the charge transport. This work would shed light on the construction of novel heterostructures for high-performance sodium-ion batteries and other energy-related devices.