Synthesis and Growth Mechanism of Bi_2S_3 Nanoribbons

摘要

This article describes a facile solvothermal method by using mixed solvents for the large-scale synthesis of Bi_2S_3 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 glycer-ol.HRTEM(high-resolution transmission electron microscopy)and SAED(selective-area electron diffraction)studies show that the as-synthesizednanoribbons had predominately grown along the[001]direction.The Bi_2S_3 nanoribbons prepared by the use of different sulfur sources have a common formation process: the initial formation of NaBiS_2 polycrystals,which serve as the precursors to Bi_2S_3,the decomposition of NaBiS_2,and the formation ofBi_2S_3 seeds in the solution through a homogeneous nucleation process; the growth of Bi_2S_3 nanoribbons occurs at the expense of NaBiS_2 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