Synthesis And Photocatalytic Properties Of Composite Materials Based On Keggin-type Polyoxometalates

In recent years,the development of low-cost photocatalysts based on semiconductor materials and utilizing visible light energy has attracted a lot of interest in energy generation and environmental remediation.Keggin-type polyacids H₃PW₁₂O₄₀ and H₃PMo₁₂O₄₀ as typical semiconductor photocatalytic material due to their outstanding structural characteristics and excellent redox ability and,show ideal performance in photocatalytic technology.In this paper,a new photo-Fenton-like catalyst is formed by complex modification and organic framework ferrocene complexation method,which greatly improves the photocatalytic activity of the original polyacid.The main research contents are as follows:?1?A new K₃PMo₁₂O₄₀/Bi VO₄photocatalyst was synthesized by solvothermal method.The phase structure,morphology and optical properties of the prepared photocatalyst were studied by physical characterization.The results show that Bi VO₄is evenly distributed on the surface of K₃PMo₁₂O₄₀ and forms a heterostructure.Driven by ultraviolet light,the efficiency of K₃PMo₁₂O₄₀/Bi VO₄ photocatalytic degradation of tetracycline and rhodamine B is higher.K₃PMo₁₂O₄₀/Bi VO₄maintained similar reactivity after four cycles,showed good catalytic stability and proposed a corresponding photocatalytic mechanism.?2?The efficient binary K₃PW_12O40/Bi VO₄ heterojunction materials were prepared by solvothermal method.The obtained K₃PW₁₂O₄₀/Bi VO₄ showed high catalytic activity for the photodegradation of metronidazole and rhodamine B.WB-4photodegraded 90.0%of metronidazole within 120 min.Due to the formation of a heterojunction structure,the material effectively induces the separation of carriers,broadens the light absorption range,improves the hole oxidation ability and electron reduction ability,and thus improves the photocatalytic activity.In addition,free radical trapping experiments show that·OH and h⁺are the main active free radicals in the catalytic system.?3?K₃PW₁₂O₄₀ and CdS nanoparticles were prepared as heterojunction conjugated materials by co-precipitation and hydrothermal method.Characterization tests showed that CdS was successfully loaded on K₃PW₁₂O₄₀ microspheres and the formation of a heterojunction between K₃PW₁₂O₄₀ and CdS promoted the efficiency of photogenerated charge separation.In addition,the photoreduction efficiency of this material for Cr???can reach 98.3%,and the efficiency of removing tetracycline and rhodamine B is 87.3%and 81.4%,indicating that the heterojunction material has significantly enhanced photocatalytic activity under visible light irradiation And good stability.In addition,based on the experimental analysis,the possible photocatalytic reaction mechanism of the prepared photocatalyst was clarified.?4?The catalysts Fe?C₅H₅?₂-PW₁₂O₄₀ and Fe?C₅H₅?₂-PMo₁₂O₄₀ were successfully prepared in aqueous solution by precipitation method,and the internal relationship between material structure and catalytic activity was fully studied.Ph OH and DCP were oxidized by the heterogeneous Fenton-like process.The results show that the Fc PW catalyst can completely oxidize it within 60 minutes,showing its excellent catalytic activity.In addition,the catalyst showed good reusability,and there was no significant decrease in performance after continuous experimental runs.Based on the analysis of the experimental results,a possible optical Fenton mechanism is proposed.Therefore,this paper successfully improved the photocatalytic activity of polyacids through the above compound modification and preparation of photo-Fenton-like agent,and increased its application value in the field of photocatalysis.