Preparation Of BiO_2-x/bismuth Oxyhalide Composite Photocatalst Study On Degradation And Antibacterial Properties

In recent years,with the rapid growth of population and the intensification of water pollution,global water resources have deteriorated.Among this wastewater,antibiotic and dye wastewater accounts for a large proportion,which may have a serious impact on the ecological environment.At the same time,the infection caused by bacteria in wastewater has brought various challenges to human beings,such as the emergence of a variety of diseases and drug-resistant bacteria,which pose a certain threat to human life and health.Among many methods to solve pollution control,photocatalysis technology can use sunlight,and will not produce secondary pollution in the purification process,and the price is relatively low.At the same time,photocatalysis technology has high efficiency,long service life and less cost.Facing the problems of water pollution and bacterial infection,it is very necessary to develop a photocatalyst with high redox ability,which can effectively remove a variety of pollutants and inactivate bacteria.These advantages of photocatalytic technology make it widely studied and developed by researchers.In this paper,the defective state of BiO_2-x was combined with BIOX（bismuth oxyhalide）to construct a heterojunction structure.Three Z-scheme heterojunction composites,BiO_2-x/BiOI,BiO_2-x/BiOBr and BiOI/BiO_2-x/BiOBr,were synthesized respectively.The construction of heterojunction materials improves the separation efficiency of photogenerated carriers,significantly enhances photocatalytic performance,and can effectively remove pollutants and inactivate bacteria.The specific research contents are as follows:（1）Firstly,BiO_2-x containing oxygen vacancies were obtained by one-step hydrothermal method,and then BiO_2-x/BiOI（BI）composites were obtained by in-situ synthesis.A series of techniques such as XRD,TEM,Raman,XPS and ESR confirmed the successful composition of BI heterojunction structure.Photocurrent and EIS show that the separation efficiency of photogenerated electrons and holes between the two semiconductors is significantly higher than that of single semiconductor material.The best sample 30%BI can degrade 96.4%rhodamine B（Rh B）and 74.5%tetracycline（TC）in 90 minutes and inactivate 100%E.coli in 15 minutes.The mechanism of the photocatalytic reaction was further determined by energy band structure analysis and an active species capture experiment.（2）Firstly,BiO_2-x was prepared,and then BiO_2-x/BiOBr（BOB）composites were obtained by in-situ synthesis.XRD,TEM and XPS verified the successful preparation of Z-scheme BOB composites.XPS and ESR revealed the existence of oxygen vacancies in the BOB heterojunction.BOB composites showed good properties in inactivating Staphylococcus aureus and degrading rhodamine B（Rh B）and tetracycline（TC）.The best sample 30%BOB can degrade 99.8%rhodamine B（Rh B）in 60 min,79.0%tetracycline（TC）in 90 min and inactivate 100%S.aureus in 20 min.The effects of initial pollutant concentration and catalyst dosage on pollutant removal were explored.The active species and possible reaction mechanisms were revealed by capture experiment and related characterization.（3）BiO_2-x and BiOIBr-55 were prepared,and then BiOI/BiO_2-x/BiOIBr（IOB）composites were prepared by in-situ synthesis.XRD,XPS,TEM and SEM showed that the double Z-scheme heterojunction IOB composites were successfully prepared.XPS and ESR techniques verified the existence of oxygen defects in the composite photocatalyst.Photoelectrochemical tests show that the separation efficiency of electrons and holes in IOB composites is high.The best sample 35%IOB composite can remove 99.6%RHB within 60 min;81%TC could be degraded within 90 min;It can kill 100%E.coli and S.aureus within 15 min.In addition,the effects of pollutant concentration,amount of photocatalyst,p H value,and inorganic compound anion on pollutant removal were discussed.Finally,the mechanism of the photocatalytic reaction was further determined by energy band structure analysis and active species capture experiment.