Study On Preparation And Performance Improvement Of Novel Niobate Photocatalytic Materials

With the rapid development of global economy,environmental pollution has attracted worldwide attention.Therefore,there is an urgent need to develop renewable energy and environmentally friendly environmental remediation technologies.The development of new organic pollutants and heavy metal pollution treatment methods has become an important subject.Among the various proposed methods,semiconductor photocatalysis technology has great potential because it could directly use solar energy to degrade harmful pollutants in water.In addition,the technology does not cause secondary pollution,the final product is CO₂and H₂O.Because of its unique physical and chemical properties and crystal structure,niobate has great potential in the application of photocatalytic technology.Therefore,this article mainly studies the preparation of new niobate photocatalytic materials and its composites.We studied the degradation effect of the prepared photocatalytic material on pollutants in water under visible light,and analyzed its degradation mechanism.The main research contents of this article are as follows:（1）A novel KNbO₃/In₂S₃nanocomposite photocatalyst was prepared by in-situ growth method.Under visible light,the obtained composites showed high photocatalytic oxidation capacity for TC（tetracycline hydrochloride）and Rh B（rhodamine B）.When the mass percentage of In₂S₃in the nanocomposite is 10 wt%,the nanocomposite material exhibits the highest photocatalytic performance for the degradation of Rh B and TC.The results of photoluminescence and transient photocurrent response showed that the transfer rate and separation efficiency of photogenerated charges are significantly improved by In₂S₃modification,which greatly improved the photocatalytic activity of nanocomposite samples.（2）A novel Bi₃NbO₇/La FeO₃p-n（BNO-LFO）heterojunction photocatalyst was successfully prepared by hydrothermal method.In the study of reduction degradation of the solution containing Cr（VI）（potassium dichromate）,it was found that compared with the weak activity of pure BNO（～7%）and LFO（～10%）,the photocatalytic reduction activity of the prepared BNO-LFO-200-5 has been greatly improved,reaching about 85%.Photocurrent and fluorescence experiments confirm that the photogenerated carriers are greatly separated because of the formation of p-n heterojunction in the composite.（3）A novel Ag₂O-KNbO₃Ⅰ-Type heterojunction composite was successfully prepared by the in-situ growth method.In all the prepared samples,the degradation of SMZ（sulfamethoxazole）under visible light showed that the 0.15Ag-Nb composite has the highest apparent rate constant of 0.060 min^-1,which is 40 times of pure KNO and 8 times of pure Ag₂O,respectively.The remarkable enhancement of photocatalytic performance could be thanked to the construction ofⅠ-Type heterojunction between KNbO₃and Ag₂O.