Synthesis Of Doped Bismuth Iodate Materials For Enhanced Photocatalytic Activity

In order to achieve the sustainable development of society,environmental pollution is one of the major challenges.Bismuth-based photocatalysts are widely used in the field of environmental photocatalysis due to their special layered structure and high activity.Bismuth iodate（BiOIO₃）is widely used in water pollution treatment,NO gas removal and gaseous Hg removal due to its good stability,non-toxic and environmentally friendly characteristics.BiOIO₃ has a special layered structure to facilitate the efficient separation of charges.However,BiOIO₃ also has some disadvantages that cannot be ignored,such as a wide band gap,a narrow optical response range,and a high recombination rate of photogenerated electrons and holes,which ultimately leads to lower photocatalytic activity.Therefore,it is of great significance to seek appropriate methods to improve the photocatalytic performance of BiOIO₃ for the theoretical research of photocatalytic materials and the effective solution of environmental pollution problems.In this paper,doping reduces the band gap of BiOIO₃ materials and improves the utilization rate of visible light;it supports carbon quantum dots（CQDs）to effectively transfer and store photo-generated electrons in the catalyst and improve the charge separation efficiency.The specific research contents are as follows:（1）BiOIO₃ was prepared by hydrothermal method,and nitrogen-doped bismuth iodate（N-BiOIO₃）was prepared by calcination method.XRD,FT-IR,HRTEM and XPS prove that N atoms are doped into the BiOIO₃ lattice;DRS and XPS valence band spectra show that the introduction of N atoms reduces the band gap of BiOIO₃materials,and improve the utilization of visible light;photocurrent confirmed that the introduction of N atoms promoted the separation of photo-generated carriers.In the LED photocatalytic degradation experiment,N-BiOIO₃ material has higher photocatalytic activity than BiOIO₃ monomer.Among them,30%N-BiOIO₃ showed the highest photocatalytic activity when degrading RhB,BPA,CIP and TC.In the experiment of degrading RhB,the degradation kinetic constant of 30%N-BiOIO₃ was10 times that of BiOIO₃ monomer.Finally,the degradation mechanism of N-BiOIO₃material was analyzed.（2）The calcination method was used to prepare 30%N-BiOIO₃（N-B）,the hydrothermal method was used to prepare CQDs,and the room temperature stirring method was used to prepare CQDs/N-B composite materials.XRD,FT-IR,XPS,TEM,SEM analysis of the material proves that the CQDs/N-B composite material was successfully prepared.DRS,photocurrent and EIS explored the photoelectric properties of the material,and confirmed that the introduction of CQDs is beneficial to the absorption of light and the separation of photo-generated carriers in the composite material.In the LED photocatalytic degradation experiment,the 6%CQDs/N-B composite exhibited the highest photocatalytic activity when degrading RhB,BPA,CIP,and TC.Among them,the degradation kinetic constants of 6%CQDs/N-B composites were 7 times and 2.8 times that of BiOIO₃ and N-B in the experiment of degrading RhB.Finally,the degradation mechanism of CQDs/N-B composites was analyzed.（3）Iodine-doped bismuth iodate（I-B）was prepared by chemical solution method,CQDs was prepared by hydrothermal method and preparation of CQDs/I-B composite material by stirring method at room temperature.XRD,FT-IR,XPS,TEM,and SEM confirmed that a compact structure was formed between CQDs and I-B,and CQDs/I-B composites were successfully prepared.DRS,photocurrent and EIS explored the photoelectric properties of the material,and confirmed that the introduction of CQDs is beneficial to the absorption of light and the separation of photo-generated carriers in the composite material.In the LED photocatalytic degradation experiment,5%CQDs/I-B composite materials showed the highest photocatalytic activity when degrading RhB,BPA and CIP.Among them,in the experiment of degrading RhB,5%CQDs/I-B composite material can completely degrade pollutants in 30 minutes.Finally,the degradation mechanism of CQDs/I-B composites was analyzed.