In-Situ Synthesis And Environmental Purification Performance Of Bismuth-Based Heteroiunction Photocatalyst

To broaden the light response range of semiconductor photocatalysts and improve the efficiency of photocatalytic reaction is the focus of the photocatalytic study. Due to its unique layered structure and excellent light absorption properties, the bismuth-based composite oxides have attracted more and more attention in recent years. Based on the rich domestic bismuth mineral resource, to develop low-cost, efficient and applying in environmental purification bismuth-based photocatalysts has good prospects. In this work, a series of bismuth-based composite photocatalysts with tightly interface, evenly distributed and matching energy level, was designed and prepared by soft chemical in-situ synthesis technology. And the prepared bismuth-based composite photocatalysts was used in the field of environmental purification, such as decomposition of organic pollutants, the sterilization of pathogenic contaminants, reduction of heavy metal ions and removal of indoor VOCs, respectively. Different experimental parameters were studied for controlling the proportion of composite materials, surface microstructure, and optical absorption performance. The influence of composite photocatalysts structure on the photocatalytic performance was also studied. The main research work is as follows:By a facile solution method at low temperature, introducing the Ti polymeric cationic to the surface of BisNbO7particles, the BiOCl/Bi5Nb3O15/TiO2composite photocatalyst was in-situ synthesized. The as-prepared composites were characterized by XRD, XPS, HR-TEM, UV-vis DRS and N2adsorption-desorption. The BiOCl/Bi5Nb3O15/TiO2composite samples have high specific surface area and dual-mesoporous structure. The multiphase interfaces formed in-situ are matching effective, which could favor for the separation of the light generated electron-hole, and thus increase the photocatalytic efficiency. The photocatalytic degradation results show that the composite photocatalysts have good photocatalytic activity for the degradation of rhodamine B and gaseous acetone. The photocatalyst degradation of rhodamine B was initial deethylation and then attacking and destruction the chromophore. The active radical O2-play an important role in the photocatalytic degradation of Rhodamine B. By hydrothermal method, the different synthesis conditions, bismuth source compounds and the effect of pH values, on the characteristic of the as-prepared Bi2O2CO3samples, such as morphology, surface functional groups, light absorption and photocatalytic activity was studied. The as-prepared samples using BiCl3as bismuth source having a smaller particle size. The absorption edge has a clear blue shift. The as-prepared samples using BiCl3as bismuth source have the highest photocatalytic activity for the degradation of methyl orange under UV irradiation. Under different pH conditions, the Bi2O2CO3sample synthesized at pH8have a hierarchical structure with self-assembled sphere-like morphology, which is favor for trapping light quantum. The sample Bi2O2CO3sample synthesized at pH8shows the best photocatalytic efficiency.The Bi2O2CO3/Bi3NbO7composite photocatalyst was synthesized by in-situ hydrothermal method and the photocatalytic bactericidal activity against E. coli was also discussed. The phase structure, surface microstructure and optical absorption performance was analyzed by a variety of characterizations. Light absorption edges of different proportion Bi2O2CO3/Bi3NbO7composites were from428-455nm. The result shows that the BiCO/BiNbO-2composite has good photocatalytic bactericidal activity. The in-situ formed Bi2O2CC3/Bi3NbO7heterojunction structure can effectively extend the life of the light generated electron-hole. And the composite photocatalyst have a large specific surface area and multi-porous structure, which is conducive to increase the reactive sites, thus enhancing the efficiency of the photocatalytic reaction.The Bi2S3/Bi2O2CO3composite photocatalyst was synthesized by in-situ hydrothermal technology and photocatalytic reduction of Cr (VI) in aqueous solutions under simulated sunlight irradiation was also studied. The phase composition, morphology, surface functional groups and light absorption property was analyzed by XRD, SEM, TEM, FT-IR and UV-vis Diffuse Reflectance. Bi2S3and Bi2O2CO3existed in the composites as rod-like fibers and plate-like structure, respectively, and the interface of two components closely integrated. The Bi2S3/Bi2O2CO3composite photocatalyst shows better adsorption performance and photocatalytic reduction activity for the Cr (VI) than the N-doped Bi2O2CO3. The tightly interfaces and matching energy level are benefit for the transferring of photo-induced electrons and improving the life of the light generated carriers, thus increasing the efficiency of the photocatalytic reaction.