Synthesis and Growth Mechanism of Bi2S3 Nanoribbons

Abstract

This article describes a facile solvothermal method by using mixed solvents for the large-scale synthesis of Bi₂S₃ nanoribbons with lengths of up to several millimeters. These nanoribbons were formed by a solvothermal reaction between Bi^III–glycerol complexes and various sulfur sources in a mixed solution of aqueous NaOH and glycerol. HRTEM (high-resolution transmission electron microscopy) and SAED (selective-area electron diffraction) studies show that the as-synthesized nanoribbons had predominately grown along the [001] direction. The Bi₂S₃ nanoribbons prepared by the use of different sulfur sources have a common formation process: the initial formation of NaBiS₂ polycrystals, which serve as the precursors to Bi₂S₃, the decomposition of NaBiS₂, and the formation of Bi₂S₃ seeds in the solution through a homogeneous nucleation process; the growth of Bi₂S₃ nanoribbons occurs at the expense of NaBiS₂ materials. The growth mechanism of millimeter-scale nanoribbons involves a special solid–solution–solid transformation as well as an Ostwald ripening process. Some crucial factors affect nanoribbon growth, such as, solvothermal temperature, volume ratio of glycerol to water, and the concentration of NaOH; these have also been discussed.