Preparation And Photocatalytic Activity Of Bismuth-Based Borate/Titanate Materials

Facing the grim situation of energy and environment problems in the world today,how to rationally utilize the limited natural resources,efficiently produce new green energy and effectively solve the problem of environmental pollution has great significance.The application of photocatalysis technology can improve the global environmental pollution problem and provide clean energy for the development of green economy.However,traditional photocatalytic materials can’t meet the requirements of industrialization.Therefore,in addition to carrying out modification studies on traditional materials to improve their photocatalytic performance,it is also necessary to develop new and efficient catalysts.Among various kinds of photocatalytic materials,bismuth-based materials have the advantages of wide light response range and low electron-hole recombination rate due to their own electronic structure and crystal structure characteristics,making them always have high research interest in the field of photocatalysis.Based on the development of new bismuth-based photocatalytic materials,the new layered bismuth-based borate and titanate photocatalytic materials were synthesized by simple high-temperature solid phase method in this paper,and the properties of the prepared materials were investigated in terms of photodegradation and water splitting.The bismuth-based borate material ABi₂B₂O₇（A=Ca、Sr）was prepared by solid-phase method and its degradation performance of tetracycline hydrochloride was explored.Under ultraviolet light condition,SrBi₂B₂O₇ and CaBi₂B₂O₇ degraded about 58%and 70%of tetracycline hydrochloride in 4 min,respectively.The research results on the degradation mechanism showed that hydroxyl radical（·OH）and superoxide radical（·O₂^-）were the main active substances that cause the decomposition of tetracycline hydrochloride.Calculation results based on first principles showed that CaBi₂B₂O₇ has a smaller effective mass of electrons and holes than SrBi₂B₂O₇ and therefore it has a higher carrier separation efficiency and higher photocatalytic activity.Two groups of MBi₄Ti₄O₁₅（M=Ca、Sr、Ba）layered bismuth-based titanate photocatalytic materials were prepared by traditional solid-phase method and molten salt method,respectively.Compared with the samples synthesized by solid phase method,CaBi₄Ti₄O₁₅ and SrBi₄Ti₄O₁₅ synthesized by molten salt method had higher photocatalytic oxygen production activities,which were about 1.97 times and 1.79times of the oxygen production rate of the samples synthesized by solid phase method.However,BaBi₄Ti₄O₁₅ showed no significant change.The oxygen production rates of the samples synthesized by solid phase method and molten salt method were 50.93and 50.79μmol·g^-1·h^-1,respectively.Using solid-phase method,M₂Bi₄Ti₅O₁₈（M=Ca、Sr、Ba）layered bismuth-based perovskite materials were prepared under different calcination temperature conditions.The performance of producing oxygen of M₂Bi₄Ti₅O₁₈（M=Ca、Sr、Ba）synthesized at900℃was tested under simulated sunlight condition.The test results showed that all the three materials had good oxygen-producing activity,and Sr₂Bi₄Ti₅O₁₈ had the highest oxygen production rate about 36.26μmol·g^-1·h^-1.