The Synthesis And Photocatalytic Evaluation Of BiOX-based Composite Photocatalyst

With the rapid development of modern industry,energy shortage and environmental pollution problems are becoming increasingly serious and threatening the development of human.Photocatalytic technology can effectively use solar energy to realize material transformation,which is a kind of green safe technology,and also has important prospects in the application field of energy and environment.However,the traditional photocatalytic materials have the disadvantages of wide bandgap,low solar energy utilization,photo-generated electron-hole pairs,which limits its application in energy and environment.Therefore,the research and development of semiconductor materials with high efficiency,sustainability and high stability are the problems that need to be solved in this field.In this paper,a series of ternary composite,g-C₃N₄/BiOI/BiOBr,pg-C₃N₄/BiOI/BiOCl,and AgI/BiOI/pg-C₃N₄ were synthesized by using bismuth oxide?BiOX?,graphite phase carbonitride?g-C₃N₄?and AgI,which were designed to improve the separation efficiency of photogenerated carriers,broaden the absorption range of visible light and enhance the photocatalytic activity.The composition,structure,morphology,photocatalytic performance and the possible mechanism of photocatalytic degradation of organic pollutants were put forward through a variety of characterization methods.The possible mechanism of photocatalytic degradation of organic pollutants is proposed,and the possible mechanism of photocatalytic degradation of organic pollutants is proposed.The main research contents are listed as follows:1.Synthesis and photocatalytic properties of g-C₃N₄/BiOI/BiOBr composites.g-C₃N₄/BiOI/BiOBr were synthesized by hydrothermal method.The structures and properties of the composites were characterized by XRD,TEM,SEM,EDS,FT-IR,DRS,XPS and PL.TEM and SEM analysis showed that g-C₃N₄ was lamellar structure,BiOI and BiOBr were lamellar structure.The results of DRS showed that g-C₃N₄/BiOI/BiOBr had obvious visible light absorption properties.Catalytic degradation experiments showed that the catalytic activity of g-C₃N₄/BiOI/BiOBr composites was the highest among the samples.The degradation rate of MB was 2.5% in 2.5 h,which was 2.5 and 3.2 times higher than that of g-C₃N₄ and BiOI/BiOBr.PL,photocurrent and EIS results showed that g-C₃N₄/BiOI/BiOBr had stronger photogenerated electrons and hole separation ability.The Capture experiments showed that during the degradation process,�OH,� O2-and h+ had a certain effect,while the h+ played a dominated role.2.Synthesis and photocatalytic properties of pg-C₃N₄/BiOI/BiOCl composites: porous pg-C₃N₄ was synthesized by a hard template method and the pg-C₃N₄/BiOI/BiOCl complex was synthesized by calcination.The structure and properties of the photocatalyst were characterized by XRD,TEM,SEM,EDS,FT-IR,DRS,XPS,PL and ESR.TEM and SEM analysis showed that pg-C₃N₄ was porous structure and BiOI and BiOCl were lamellar structure.The results of DRS showed that pg-C₃N₄/BiOI/BiOCl had obvious visible light absorption properties.Catalytic degradation experiments showed that the catalytic performance of pg-C₃N₄/BiOI/BiOCl was better than that of pg-C₃N₄,BiOI,BiOCl and BiOI/BiOCl.The degradation rate of MO was 85% after 2.5 h,and the degradation rate constant was 1.84,8,24 and 4 times high than pg-C₃N₄,BiOI,BiOCl and BiOI/BiOCl.PL,photocurrent and EIS results showed that pg-C₃N₄/BiOI/BiOCl had stronger photogenerated electrons and holes separation ability.Capture experiments and ESR indicated that during degradation process,�OH has no effect,�O2-had a certain effect and h+ played a dominated role.3.Synthesis and photocatalytic activity of AgI/BiOI/pg-C₃N₄ composites: of BiOI/pg-C₃N₄ was synthesized by a calcination method,AgI/BiOI/pg-C₃N₄ was synthesized by the precipitation method.The structure and properties of the photocatalyst were characterized by XRD,TEM,SEM,EDS,FT-IR,DRS,XPS,PL and ESR.TEM and SEM analysis showed that pg-C₃N₄ was porous structure,BiOI was lamellar structure,and AgI was attached to the surface of BiOI.The results of DRS showed that AgI/BiOI/pg-C₃N₄ had the strongest visible light response and widest light absorption range.Catalytic degradation experiments showed that the catalytic performance of AgI/BiOI/pg-C₃N₄ was better than that of pg-C₃N₄,BiOI and BiOI/pg-C₃N₄.The degradation rate of MO was 85% in 50 min,which was 10,5.6 and 3.5 times of BiOI,pg-C₃N₄ and BiOI/pg-C₃N₄.PL,photocurrent and EIS results showed that the separation ability of photogenerated electron-hole pairs in AgI/BiOI/pg-C₃N₄ is better than other samples.ESR results showed that �OH and �O2-were main active species in the degradation process.Antimicrobial activity showed that the certain concentration of AgI/BiOI/pg-C₃N₄ could inactivate E.coli in 15 min,and its antimicrobial activity was better than BiOI/pg-C₃N₄.