Structural Regulation Of Bismuth Oxychloride Nanosheets And Preparation And Photocatalytic Performance Of Their Composite

Bismuth chloride oxide(BiOCI)is an important two-dimensional material,and its unique layered structure lays the foundation for the preparation of efficient photocatalysts.However,BiOCI still faces many problems in practical applications,for example:(1)the wider bandgap of BiOCI reduces the utilization of sunlight,which can only absorb ultraviolet light but cannot make good use of the visible region;(2)The short carrier lifetime and easy compounding of the excited charges largely affect the photocatalytic activity.In view of this,we prepared a series of bismuth chlorooxide nanosheets and their composite catalysts to enhance the catalytic performance,and the main research is divided into the following three parts:1.Highly crystalline BiOCI nanosheets with nice UV-catalytic degradation properties were prepared by a simple hydrothermal method.The higher crystallinity of BiOCI makes the molecules closely aligned with each other,which improves the separation efficiency of photogenerated charges and shows high degradation efficiency for norfloxacin with better photocatalytic stability and recyclability.2.The photocatalytic activity of BiOCI was further enhanced by interfacial engineering.Plasmonic Bi/BiOCl nanomicrosphere heterojunctions were prepared in situ by a one-step solvothermal method.Due to the in situ formation of the heterogeneous interface,the metal Bi is firmly anchored to the surface of BiOCI,which allows for effective charge transfer.The resulting Bi/BiOCl heterojunction structure with a narrower bandgap of 3.05 eV and mesoporous structure extends the photoresponse to the visible region and provides sufficient surface active sites.In terms of catalytic activity,the photocatalytic degradation rate of highly toxic norfloxacin by Bi/BiOCl heterojunctions was 4.3 times higher than that of pristine BiOCI nanosheets.This is attributed to the in situ formation of Bi/BiOCl heteroj unctions and the single Bi surface plasmon resonance(SPR)effect that promotes charge transfer,as well as the pronounced photothermal effect.This strategy provides a new idea for the preparation of high-performance metal/semiconductor heterojunction photocatalysts.3.Based on the interface engineering,the intrinsic structure of BiOCl was tuned and Mn-doped Bi/BiOCl photocatalyst system was constructed,which further enhanced the absorption of light.Mn doping can introduce intermediate energy levels in the semiconductor structure,both as a bridge for electron leap and to inhibit electron and hole complexation.The doping of Mn ions generates dipole interactions that change the local electronic structure of BiOCl,while increasing the specific surface area of BiOCl and increasing the number of mesopores,providing more abundant surface active sites for catalytic reactions.The combined effect of Mn doping and metal Bi loading reduces the forbidden band width of BiOCl,promotes the absorption of visible light,and enhances the photocatalytic degradation of BiOCl.Mn-doped Bi/BiOCI degrades norfloxacin 1.15 times more efficiently than Bi/BiOCl and 6 times more efficiently than BiOCl.This is the result of the synergistic effect of Mn doping to change the energy level structure and Bi metal to increase the light absorption.The photocatalytic system constructed by this modification strategy provides a new idea to build efficient heterojunction photocatalysts.