Novel single-source precursors approach to prepare highly uniform Bi ₂S₃ and Sb₂S₃ nanorods via a solvothermal treatment

High-quality Bi₂S₃ and Sb₂S₃ nanorods on a large scale were successfully synthesized by the solvothermal treatment of a novel kind of single-source precursors (SSPs), metal di-n-octyl-dithiophosphates (M[S₂P-(OC₈H ₁₇)₂]₃, M = Bi, Sb). The X-ray powder diffraction (XRD) patterns show that both of these products belong to the orthorhombic M₂S₃ phase. The experimental results show that the Bi₂S₃ nanorods can be easily prepared in air at ≥ 140°C for 5 h in the presence of oleylamine. Transmission electron microscopy (TEM) images show the rodlike appearance of Bi₂S ₃ with a diameter of 7-21 nm and length of several hundred nanometers under the various reaction conditions. The effects of reaction parameters, such as reaction time, temperature, and concentration of the precursor, on the growth of nanorods were discussed in detail. The mechanism of the formation process of the nanorods was proposed. We also demonstrate that this method can be extended to the synthesis of Sb₂S₃ nanorods, which have an average diameter in the range of 45 nm and a length in the range of 1 μm. The optical absorption experiment shows that these nanorods are semiconductor with bandwidth E_g = 1.67 eV for Bi₂S₃ and 1.76 eV for Sb₂S₃, both near to the optimum for photovoltaic conversion, suggesting these nanorods could be used in solar energy and photoelectronic applications.