General and Scalable Solid-State Synthesis of 2D MPS₃ (M = Fe, Co, Ni) Nanosheets and Tuning Their Li/Na Storage Properties

The scalable preparation of 2D nanomaterials is challenging and highly desirable for fundamental interest and practical applications. Herein, an efficient solid-state method is developed for producing emerging 2D ternary layered metal phosphorus trichalcogenide (MPS₃, M = Fe, Co, Ni) nanosheets on a large scale. The high-quality MPS₃ single-crystal nanosheets are exposed with (00l) facets and have an average lateral size of ≈200 nm and an average thickness of ≈18 nm. Moreover, their interlayer spacing can be expanded by intercalating propylamine at room temperature. For Li/Na storage applications, such MPS₃ nanosheets can achieve: i) high specific capacity owing to the intrinsic composition, realizing a theoretical specific capacity higher than the corresponding metal oxides, and ii) superior rate capability due to the large extrinsic pseudocapacitive contribution from surface redox reactions. Remarkably, the propylamine-intercalated samples show improved Li/Na storage performance due to the better electrical conductivity and enlarged interlayer distance to allow easier ion accessibility and faster ion diffusion. Impressively, the Na-ion batteries based on the intercalated NiPS₃ nanosheets deliver 1090 and 536 mA h g⁻¹ at 0.05 and 5.0 A g⁻¹, respectively. This work paves the way for developing MPS₃ nanosheets for energy storage and conversion, catalysis, and so on.