Research On The Preparation And Photocatalytic Activity Of Bi Based Composite Photocatalysts

Photocatalysis is considered to be an effective solution for the current energy and environmental crises caused by industrial development.Recently,much attention has been given to a series of visible light active Bi-based photocatalysts,due to its unique layered structure and excellent electronic band structure.In this paper,based on typical Bi₂MoO₆ and BiOI,a series of bismuth-based composite visible light photocatalysts was designed and prepared by soft chemical synthesis technology.The as-prepared samples was used in the decomposition of organic pollutants,such as rhodamine B?RhB?,methylene blue?MB?,and bisphenol A?BPA?.The influence of composite structure,compound proportion,surface microstructure,and optical absorption performance on the photocatalytic performance was studied.The carrier transfer paths and the intrinsic reason of photocatalytic degradation of organic pollutants was revealed.The details are summarized briefly as follows:1.Microspheric g-C₃N₄/Bi₂MoO₆ photocatalyst was developed through a one-step template-free solvothermal route.The formation of heterojunction structures was confirmed which exhibited microsphere-like morphology and composed of smaller nanoplates.The as-prepared samples exhibited superior photocatalytic activity towards the degradation of RhB and MB under visible light irradiation.The photo-degradation of dye molecules is mainly attributed to h⁺and partly to·O₂^-and·OH radicals.The enhanced photocatalytic activity could be attributed to their strong visible light absorption,the high migration efficiency of photo-induced carriers,and the interfacial electronic interaction.2.A ternary Ag/AgCl/Bi₂MoO₆ plasmonic photocatalyst was fabricated through a two-step synthesis method.The visible light absorption of the as-prepared samples had been greatly enhanced owing to the Ag⁰ particles.The obtained flower-like Bi₂MoO₆ were composed of nanoplates,on the surface of which Ag/AgCl particles were distributed.The highest degradation efficiency was observed for the AAB-30 sample.The degradation of pollutants was mainly ascribed to the strong oxidation ability of h⁺.The activity enhancement was mainly attributed to the high separation efficiency of electron–hole pairs on their heterojunction interfaces.3.A novel BiOI/Bi₂MoO₆ composites were prepared by precipitation–deposition method.The as-prepared composites exhibit excellent photocatalytic activity and stability towards the degradation of MB and BPA under visible light irradiation.The optimal composite with 25%BiOI content shows the highest photocatalytic activity.The degradation of MB is driven mainly by the participation of·O₂^-,h⁺,and·OH radicals.The enhanced photocatalytic activity is attributed to the formation of heterojunction that can facilitate the separation and transfer of the photogenerated charge carriers.4.A novel BiOI/Zn₂SnO₄ composites with a heterostructure have been synthesized via a chemical deposition method,which were more photoactive than pure BiOI and Zn₂SnO₄,The BiOI/ZSO-35 composite shows excellent photocatalytic activities in the degradation of MB,RhB,and BPA under visible or UV light irradiation,respectively.The reactive species·OH,·O₂^-,h⁺,and ¹O₂ participated in the photo-degradation reaction and played equivalent role in the photocatalytic process under visible light irradiation.However,under UV light irradiation,the effect of h⁺and ¹O₂ played vital important contributions,but the participation of·OH and·O₂^-played a minor role.The activity enhancement was mainly ascribed to the formation of a heterojunction between BiOI and Zn₂SnO₄,which facilitated the transfer and separation of photogenerated electron–hole pairs.5.A novel BiOI/Zn₂Ge O₄ composite has been synthesized by simple chemical bath approach.The photo-degradation of bisphenol A indicates that the BiOI/Zn₂GeO₄ composites are more photoactive than BiOI and Zn₂GeO₄.The photocatalytic activity enhancement,which is mainly ascribed to the strong sensitization of BiOI to Zn₂Ge O₄,broadened the photoabsorption of Zn₂GeO₄,and the heterojunction of BiOI/Zn₂GeO₄ facilitated the transfer and separation of photo-generated charge carriers.In addition,the active species trapping experiments showed that h⁺and·O₂^-were the dominant reactive species,while molecular oxygen plays a fatal role for photocatalytic interactions.A possible degradation mechanism is proposed.Furthermore,the BiOI/Zn₂GeO₄ photocatalysts exhibit a higher mineralization capacity for bisphenol A.