Morphology control of Bi₂S₃ nanostructures and the formation mechanism

Bismuthinite (Bi₂S₃) nanostructures were prepared by a hydrothermal method with sodium ethylenediaminetetraacetate (EDTA-Na ₂). The morphology of Bi₂S₃ nanostructures was changed from a nanorod to a nanoplate by presence of the EDTA-Na₂. The altered morphology was caused by the capping effect of EDTA-Na₂ with Bi³⁺ ions, which induces the suboptimal growth direction due to partially blocking the preferential orientation direction. When the EDTA-Na ₂/Bi³⁺ molar ratio=1, the growth of Bi₂S ₃ nanostructures was not allowed due to the chelating effect of EDTA-Na₂. The obtained Bi₂S₃ nanorods, stacked nanorods, nanoplates and nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) pattern. A possible formation mechanism of these morphologies was proposed. The successful synthesis of various morphologies of nanostructured Bi₂S₃ may open up new possibilities for thermoelectric, electronic and optoelectronic uses of nanodevices based on Bi₂S ₃ nanostructure.