Preparation Of Bi₂S₃ Nanocomposite And Its Performance Study

Bi₂S₃ is a non-toxic semiconductor with stable structure and strong capability of light absorption. Because of its superior performance, Bi₂S₃ has good practical values in many aspects. The performance is closely related to the structure, composition, etc. Bi₂S₃ has a very narrow energy band, which is only about 1.3 eV, making the electron-hole pairs recombine quickly. As a result, the catalytic application of visible light is limitted. In order to get a better application prospect, the modified work of Bi₂S₃ becomes a hotspot. Nanomaterials play the best property through defect, morphology and heterojunction control, so that they can be better applied in real life. Among them, the study of heterojunction control is particularly active.In heterojunction control process, the option of heterojunction material is very important, as well as the tight binding degree between heterojunction. It is because the tightness between heterojunction directly affects the transmission of electrons and holes. To solve above problems, through a simple ion exchange method, we combined Bi₂S₃ with three other nanomaterials containing Bi. In addition, this paper also made the interface properties of nanomaterials and crystal defect design as a guide. Through the quantum size effect, morphology control and control of the exposed crystal facets, the photocatalytic performance under visible-light irradiation was enhanced. The main works are as follows:（1） BiPO₄/Bi₂S₃ heterojunction was successfully prepared by ion exchange method and the photocatalytic performance under visible-light irradiation improved obviously, which could be attributed to the high separation efficiency of electron-hole pairs and the enhanced light absorption. The results showed that BB-2 had the best photodegradation ability under visible-light irradiation. Photocatalytic mechanism showed that excessive Bi₂S₃ generated on the surface of BiPO₄, not only made the active sites reduce gradually, but also might lower the separation efficiency of electron-hole pairs. What’s more, through this method, the size of Bi₂S₃ could be controlled effectively, making it have the quantum size effect.（2） Bi₂S₃ was generated on the surface of the BiOCl with exposed different crystal facets by ion exchange method. It was found that the photocatalytic performance of BiOCl depended on its exposed facets. In addition, the photocatalytic performance of BiOCl-010 was better than that of BiOCl-001 under visible-light irradiation. It could be ascribed to the energy band of BiOCl-010 was smaller and specific surface area was larger, which could make the separation rate of electron-hole pairs much higher. Besides, the generation mechanism of Bi OCl and the influencing factors of BiOCl with exposed different crystal facets were studied as well.（3） Bi₂WO₆/Bi₂S₃ heterojunction with uniform size, good dispersivity and firm structure was generated by ion exchange method. And it could photodegrade organic phenol solution in visible light, controlling the organic matter in the environment. The enhanced photocatalytic activity was attributed to the structure, which could narrow the energy band, accelerate the separation rate of electron-hole pairs and improve the light absorption. What’s more, the position of conduction band and valence band also had effects on photodegrading the organic molecule.In this article, combined Bi₂S₃ with other three different nanomaterials through a simple ion exchange method, the heterojunction had a highly dense structure. With this structure, it could realize the electric field coupling between two types of semiconductor. Besides, through the band matching theory and synergistic effect, the nanomaterials materials could play the best performance, so as to realize the modification research of nanomaterials.