Synthesis and transport properties of large-scale alloy Co_0.16Mo_0.84S₂bilayer nanosheets

Synthesis of large-scale highly crystalline two-dimensional alloys is significant for revealing properties. Here, we have investigated the vapor growth process of high-quality bilayer Co_xMo_1-xS₂(x = 0.16) hexagonal nanosheets systematically. As the initial loading of the sulfur increases, the morphology of the Co_xMo_1-xS₂(0 < x ≥ 1) nanosheets becomes hexagons from David stars step by step at 680 °C. We find that Co atoms mainly distribute at the edge of nanosheets. When the temperature increases from 680 to 750 °C, high-quality cubic pyrite-type crystal structure CoS₂grows on the surface of Co_xMo_1-xS₂nanosheet gradually and forms hexagonal film induced by the nanosheet. Electrical transport measurements reveal that the Co_xMo_1-xS₂nanosheets and CoS₂films exhibit n-type semiconducting transport behavior and half-metallic behavior, respectively. Theoretical calculations of their band structures agree well with the experimental results.