Unexpected Epitaxial Growth of a Few WS₂ Layers on {11̅00} Facets of ZnO Nanowires

Core–shell nanowires are an interesting and perspective class of radially heterostructured nanomaterials where epitaxial growth of the shell can be realized even at noticeable core–shell lattice mismatch. In this study epitaxial hexagonally shaped shell consisting of WS₂ nanolayers was grown on {11̅00} facets of prismatic wurtzite-structured [0001]-oriented ZnO nanowires for the first time. A synthesis was performed by annealing in a sulfur atmosphere of ZnO/WO₃ core–shell structures, produced by reactive dc magnetron sputtering of an amorphous a-WO₃ layer on top of ZnO nanowire array. The morphology and phase composition of synthesized ZnO/WS₂ core–shell nanowires were confirmed by scanning and transmission electron microscopy (SEM and TEM), micro-Raman, and photoluminescence spectroscopy. Epitaxial growth of WS₂(0001) layer(s) on {11̅00} facets of ZnO nanowire is unexpected due to incompatibility of their symmetry and structure parameters. To relax the interfacial incoherence, we propose a model of ZnO/WS₂ interface containing WS₂ bridging groups inside and use first-principles simulations to support its feasibility.