Preparation and formation process of α-MnS@MoS₂ microcubes with hierarchical core/shell structure

α-MnS@MoS₂ microcubes with hierarchical core/shell structure are prepared by one-step hydrothermal method in a reaction system of δ-MnO₂ nanowires, thioacetamide and Na₂MoO₄ at 200°C for 24h, and the formation process and phase transition behavior has been investigated in detail. Research results indicate that uniform nanosheets of MoS₂ with thickness of about 20nm and size up to hundreds of nanometers are vertically grow on the surface of α-MnS core, and the amount of sodium molybdate plays a crucial role in adjusting the crystal phase and structure of the obtained materials. The formation process of α-MnS@MoS₂ microcubes with hierarchical core/shell structure consist of four stages, δ-MnO₂ nanowires with layered structure are firstly transforms into tetragonal Mn₃O₄ nanoparticles, then into γ-MnS hexagonal prisms and α-MnS microcubes, and finally into α-MnS@MoS₂ microcubes. In compare with β-MnS and γ-MnS phases, α-MnS can be formed in α-MnS@MoS₂ microcubes because it has not only higher lattice energy, but also the lowest Gibbs free energy and the sufficient activation energy at high hydrothermal treatment temperature. By using this one-step hydrothermal technology without template assisted route, other transition metal sulfide materials with novel core/shell structure and morphology can be designed and prepared by selecting transition metal and adjusting the amount of sulfur source.