Construction Of Bi₄O₅I₂ Based Photocatalytic Composite And Study On Its Photocatalytic Oxidation Performance Under Visible Light

Bismuth halide photocatalytic materials have attracted extensive attention because of their positive valence band,non-toxicity,good optical stability,unique layered alternating structure and good visible light response performance.However,due to the weak light response ability,low photon utilization rate,photogenerated carrier recombination rate and other shortcomings,the practical application is limited.In this study,quantum dot modification,solid solution recombination,heterostructure construction and other methods were used to improve the photocarrier separation efficiency and photocatalytic oxidation capacity of bismuth halide photocatalytic materials.The specific research content is as follows:（1）N,S-GQDs quantum dots were prepared by solvothermal method,and N,S-GQDs/Bi4O5BrxI2-x hybrid materials were synthesized by one-step temperature-controlled in situ coprecipitate method.Compared with Bi₄O₅I₂ and Bi4O5Br2 alone,N,S-GQDs/Bi4O5BrxI2-x has significantly improved the photocatalytic degradation performance of phenol under visible light irradiation.The apparent rate constant Kapp of NSBBI-15 was 0.0404 min-1,which was 33.38 times of Bi4O5Br2,3.96 times of Bi₄O₅I₂,and 3.81 times of Bi4O5Br0.8I1.2,respectively.This is mainly attributed to the enhanced visible light absorption performance of the catalyst after the introduction of N,S-GQDs,the electron enrichment effect of quantum dots and the multiple light reflection of Bi4O5BrxI2-x sheet structure jointly promote the effective separation of photogenerated carriers.（2）Bi₂MoO₆ with 3D microsphere structure was synthesized by hydrothermal method,and then Bi₂MoO₆/Bi4O5l2 heterojunction was synthesized by in-situ coprecipitationcalcination method.Under the irradiation of visible light,when the compound amount of Bi₂MoO₆ in Bi₂MoO₆/Bi₄O₅I₂ heterojunction is 0.5g,the photocatalytic degradation of phenol is the best,and the internal photocatalytic degradation efficiency of phenol reaches 94.7%in 120min.The enhanced activity of Bi₂MoO₆/Bi₄O₅I₂ heterojunction is attributed to the Z-type heterojunction formed by Bi₂MoO₆ and Bi₄O₅I₂,which promotes the separation and transfer of photoelectron-hole,while maintaining the electron reduction ability of Bi₄O₅I₂ and the hole oxidation ability of Bi₂MoO₆.（3）WO₃/Bi₄O₅I₂ heterostructure was successfully synthesized by simple solvothermic calcination method.The morphology and structure of WO₃/Bi₄O₅I₂ heterostructure were characterized by XRD,SEM,TEM and XPS,and the photocatalytic degradation performance of the system was studied by using phenol as a simulated organic wastewater.The photocatalytic activity of WO₃/Bi₄O₅I₂ heterojunction was superior to that of WO₃ and Bi₄O₅I₂.Meanwhile,the heterojunction catalyst also achieved excellent photocatalytic activity of tetracycline hydrochloride and norfloxacin.