Preparation and Optical Properties of Spherical Bi2S3 Nanoparticles by In Situ Thermal Sulfuration Method

Spherical Bi2S3 nanoparticles (NPs) were prepared by a facile in situ thermal sulfuration method. Different Bi2S3 samples were obtained by controlling the sulfuration time. The products were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), Raman and Fourier-transform infrared (FT-IR) methods. The optical properties were examined by UV-visible-near-infrared (UV-Vis–NIR) and photoluminescence (PL) techniques. The results show that the phase of the products after sulfuration is pure and the spherical shape of Bi NPs has been successfully transmitted to Bi2S3 samples. The light absorption edges exhibit red shift to 1060 nm while the light emission displays blue shift to 868 nm, compared with the energy bandgap of bulk Bi2S3. The reason for the special optical properties of Bi2S3 NPs by this in situ sulfuration route is considered to associate with the defects and quantum size effect of NPs.