Molybdenum Disulfide Induced Phase Control Synthesis of Multi‐dimensional Co3S4‐MoS2 Heteronanostructures via Cation Exchange

Abstract Phase control over cation exchange (CE) reactions has emerged as an important approach for the synthesis of nanomaterials (NMs), enabling precise determination of their reactivity and properties. Although factors such as crystal structure and morphology have been studied for the phase engineering of CE reactions in NMs, there remains a lack of systematic investigation to reveal the impact for the factors in heterogeneous materials. Herein, we report a molybdenum disulfide induced phase control method for synthesizing multidimensional Co 3 S 4 ‐MoS 2 heteronanostructures (HNs) via cation exchange. MoS 2 in parent Cu 1.94 S‐MoS 2 HNs are proved to affect the thermodynamics and kinetics of CE reactions, and facilitate the formation of Co 3 S 4 ‐MoS 2 HNs with controlled phase. This MoS 2 induced phase control method can be extended to other parent HNs with multiple dimensions, which shows its diversity. Further, theoretical calculations demonstrate that Co 3 S 4 (111)/MoS 2 (001) exhibits a higher adhesion work, providing further evidence that MoS 2 enables phase control in the HNs CE reactions, inducing the generation of novel Co 3 S 4 ‐MoS 2 HNs. As a proof‐of‐concept application for crystal phase‐ and dimensionality‐dependent of cobalt sulfide based HNs, the obtained Co 3 S 4 ‐MoS 2 heteronanoplates (HNPls) show remarkable performance in hydrogen evolution reactions (HER) under alkaline media. This synthetic methodology provides a unique design strategy to control the crystal structure and fills the gap in the study of heterogeneous materials on CE reaction over phase engineering that are otherwise inaccessible.