钙钛矿结构铁酸锶光催化剂的制备及其在光催化过程中稳定性研究
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摘要
采用两种技术路线合成了钙钛矿型SrFeO3光催化剂,并对其光催化行为进行深入研究。结果表明,聚乙二醇的加入对纯相SrFeO3的形成有一定的影响。当体系中不加入聚乙二醇时,无论怎样改变反应条件,最终产物中仍含有SrCO3杂质;当体系中加入聚乙二醇时,能够得到纯相SrFeO3。甲基橙光降解实验结果表明,与纯相的SrFeO3相比,杂相的SrFeO3在可见光下具有较高的活性。光催化稳定性研究表明,含有杂相的SrFeO3光催化实验后其自身结构发生晶格坍塌,而纯相SrFeO3光催化测试后样品的结构没有明显变化,由此可以推出SrFeO3所显示的光催化活性有可能来自于其晶格内的Fe4+离子和表面氧空位的共同作用。
SrFeO3was prepared through two lines and its photocatalytic behavior was investigated in detail.The experimental results show that the addition of polyethylene glycol has a certain impact on the formation of pure phase SrFeO3.When polyethylene glycol was not added,the final product contains SrCO3 impurities,which may be due to the samples reacted with CO2 in surrounding environment after cooling process.When polyethylene glycol was added,the pure phase SrFeO3 can be obtained.The possible reason is that during the sol-gel process,citric acid and ethylene glycol can form organic network which has excellent organic thermal stability and not prone to segregation during calcination,so the pure phase SrFeO3 can be prepared.The photodegradation results showed that compared with the pure phase SrFeO3,miscellaneous phase SrFeO3 has much higher photocatalytic activity,which may be due to the oxygen vacancies in the surface of pure phase SrFeO3 was much fewer than of impurity SeFeO3.Photocatalytic stability studies displayed that the lattice structure of impurity SrFeO3 collapsed and the pure phase SrFeO3 is not changed after photocatalytic experiment,which indicates that SrFeO3 photocatalytic activity possibly comes from Fe4+ ions in the lattice reacted with the surface oxygen vacancies.
SrFeO3was prepared through two lines and its photocatalytic behavior was investigated in detail.The experimental results show that the addition of polyethylene glycol has a certain impact on the formation of pure phase SrFeO3.When polyethylene glycol was not added,the final product contains SrCO3 impurities,which may be due to the samples reacted with CO2 in surrounding environment after cooling process.When polyethylene glycol was added,the pure phase SrFeO3 can be obtained.The possible reason is that during the sol-gel process,citric acid and ethylene glycol can form organic network which has excellent organic thermal stability and not prone to segregation during calcination,so the pure phase SrFeO3 can be prepared.The photodegradation results showed that compared with the pure phase SrFeO3,miscellaneous phase SrFeO3 has much higher photocatalytic activity,which may be due to the oxygen vacancies in the surface of pure phase SrFeO3 was much fewer than of impurity SeFeO3.Photocatalytic stability studies displayed that the lattice structure of impurity SrFeO3 collapsed and the pure phase SrFeO3 is not changed after photocatalytic experiment,which indicates that SrFeO3 photocatalytic activity possibly comes from Fe4+ ions in the lattice reacted with the surface oxygen vacancies.
引文
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[2]杨秋华.纳米钙钛矿型ABO3复合氧化物的光催化氧化还原活性[D].天津:天津大学,2002.
[3]Ji L S,Ding T,Li Q B,et al.Study of photocatalytic performance of SrFeO3-xby ultrasonic radiation[J].Catalysis Communications,2007,8:963-966.
[4]Yang Y,Cao Z Q,Jiang Y S,et al.Photoinduced structural transformation of SrFeO3and Ca2Fe2O5during photodegradation of methyl orange[J].Materials Science and Engineering B,2006,132:311-314.
[5]Harizanov O A.Sol-gel BaTiO3from a peptized solution[J].Materials Letters,1998,34:232-236.
[6]Majid A,Tunney J,Argue S,et al.Preparation of SrFeO~2.85perovskite using a citric acid assisted Pechini-type method[J].Journal of Alloys and Compounds,2005,398:48-54.