Sulfur-doped zinc oxide (ZnO) Nanostars: Synthesis and simulation of growth mechanism
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- Cho, J., Lin, Q., Yang, S. et al. Nano Res. (2012) 5: 20. doi:10.1007/s12274-011-0180-3
We present a bottom-up synthesis, spectroscopic characterization, and ab initio simulations of star-shaped hexagonal zinc oxide (ZnO) nanowires. The ZnO nanostructures were synthesized by a low-temperature hydrothermal growth method. The cross-section of the ZnO nanowires transformed from a hexagon to a hexagram when sulfur dopants from thiourea [SC(NH2)2] were added into the growth solution, but no transformation occurred when urea (OC(NH2)2) was added. Comparison of the X-ray photoemission and photoluminescence spectra of undoped and sulfur-doped ZnO confirmed that sulfur is responsible for the novel morphology. Large-scale theoretical calculations were conducted to understand the role of sulfur doping in the growth process. The ab initio simulations demonstrated that the addition of sulfur causes a local change in charge distribution that is stronger at the vertices than at the edges, leading to the observed transformation from hexagon to hexagram nanostructures.