Study On Preparation, Characterization And Properties Of The Nanobisumuth-based Heterojunction Photocatalysts

This thesis is aimed at the existence problem in photocatalytic technology, such as low photocatalytic efficiency, low solar utilization rate and high cost. The target is to develop the novel composite photocatalyst with visible light response.Bismuth-based semiconductor was chosen as the supporter material of photocatalysts to design and optimize their photocatalytical properties.The details are summarized briefly as follows:1. The BiFeO₃ nanomaterial was prepared by a modified sol-gel method.L-cysteine was selected as sulfur source and Bi₂S₃ was in-situ growth on the surface of BiFeO₃ by ion exchange method. The flower-like Bi₂S₃/BiFeO₃ sphere heterojunction photocatalyst was able to degrade malachite green（MG） in 60 min.Due to the formation of heterojunction between Bi₂S₃ and BiFeO₃, the photocatalytic activity was significantly improved. The growth and photocatalysis mechanism of the photocatalytic material were discussed. Therefore, this kind of composite materials can be a promising photocatalyst for water purification in the actual environment pollution control.2. The g-C₃N₄/BiFeO₃ heterojunction nanomaterial was successfully synthesized by a modified sol-gel method and characterized by a series of test equipments. Owing to the intimate combination between g-C₃N₄ and BiFeO₃ and good electronic transport properties of g-C₃N₄, photogenerated electron and hole can separate effectively and the photoresponding range was extended. The g-C₃N₄/BiFeO₃ heterojunction organic pollutants degradation showed great potential for the degradation of persistent organic pollutants.3. The g-C₃N₄ nanomaterials were prepared by pyrolysis melamine. The g-C₃N₄/BiVO₄ was synthesized by the solvothermal method using ethylene glycol as solvent and characterized. Due to the excellent photo-carrier transport properties of g-C₃N₄, it is possible to improve the separation efficiency of photogenerated electrons and holes and effectively restrain the recombination of the photogenerated electrons and holes. Thus the photocatalytic performance of the g-C₃N₄/BiVO₄ photocatalyst was reinforced. and which can accelerate the photodegradation of organic pollutants in water. The heterojunction material can completely photodegradate 100 mL 20 mg/L MG solution in 40 minutes, which provides probability in the practical application.