The role of Al2O3 interlayer in the synthesis of ZnS/Al2O3/MoS2 core-shell nanowires

During the synthesis of heterostructured nanomaterials, unwanted structural and morphological changes in nanostructures may occur, especially when multiple sequential growth steps are involved. In this study, we describe a synthesis strategy of heterostructured ZnS/Al₂O₃/MoS₂ core-shell nanowires (NWs), and explore the role of the Al₂O₃ interlayer during synthesis. Core-shell NWs were produced via a four-step route: (1) synthesis of ZnO NWs on a silicon wafer, (2) deposition of thin Al₂O₃ layer by ALD, (3) magnetron deposition of MoO₃ layer, and (4) annealing of the sample in the sulphur atmosphere. During sulphurization, ZnO is converted into ZnS, and MoO₃ into MoS₂, while the Al₂O₃ interlayer preserves the smooth surface of an NW required for the growth of a continuous MoS₂ shell. The resulting ZnS/Al₂O₃/MoS₂ core-shell NWs were characterized by transmission electron microscopy, X-ray diffraction and photoelectron spectroscopy, Raman spectroscopy, and optical photoluminescence spectroscopy. A reported strategy can be used for the synthesis of other core-shell NWs with a transition metal dichalcogenides (TMDs) shell to protect the NW core material that may otherwise be altered or damaged by the reactive chalcogenides at high temperatures.