【作者】 万永彪；

【导师】 赵莲花；

【作者基本信息】 延边大学 ， 无机化学， 2010， 硕士

【摘要】 本论文致力于纳米钙钛矿型氧化物A(Mg、Ca、Sr)TiO3和另类可见光催化剂钒酸铋的制备、表征和光催化性能的研究。一、采用溶胶-凝胶法,制备了纳米钙钛矿型氧化物MgTi03、CaTi03、SrTiO3,利用热重-差热(TG-DTA)、X-射线衍射(XRD)、紫外可见分光光度计(UV-Vis)、X-射线光电子能谱(XPS)等分析手段进行了表征。通过光催化降解液相悬浮体系中亚甲基蓝和气相中三氯乙烯,比较了三种钙钛矿型催化剂的光催化活性。结果表明：A位原子不同催化剂晶系结构不同,导致其最佳活性的烧结温度不同,MgTiO3为700℃,CaTiO3、SrTiO3为80℃；其中CaTiO3的光催化活性最佳,原因是CaTiO3光催化剂表面吸附氧能力较强,提供了较多的表面活性物种。二、采用水相沉淀法,以Bi(N03)3·5H20和NH4VO3为原料,在不同煅烧温度下,制备出具有单一晶相的单斜白钨矿型BiVO4。以亚甲基蓝染料为目标降解物,研究了不同煅烧温度对样品可见光催化活性的影响。同时尝试利用改良的水相沉淀法-熔盐辅助法制备单斜BiVO4,以期望提高其可见光催化活性。结果表明：在不同煅烧温度(300℃、400℃、500℃、600℃)下可以成功制备出具有单一晶相的单斜白钨矿型BiVO4；400℃时制得的样品的可见光催化活性最高；通过熔盐辅助法制得的单斜白钨矿型BiVO4的光催化活性得到了明显的提高,熔盐的投入量对BiVO4的可见光催化活性有着重要影响。三、采用水相沉淀法,以Bi(NO3)。·5H20和NH4VO3为原料,在低温条件下制备出具有单一晶相的四方白钨矿型和单斜白钨矿型BiVO4,研究了pH对样品的结构和可见光催化活性的影响。结果表明：采用水相沉淀法,在室温下能够制得单一晶相的四方白钨矿型BiVO4,而在110℃下能够制得单斜白钨矿型BiVO4;pH值在低温合成过程中影响着样品的晶型,过酸或过碱条件都不利于单斜相的形成；110℃C条件下,pH=7时样品的光催化活性最高,原因主要是其具有较小的晶粒尺寸和较强的表面吸附氧能力。该项研究通过研究钙钛矿型氧化物A(Mg、Ca、Sr)Ti03结构及其光催化性能,为AB03钙钛矿型复合氧化物光催化剂中,A位金属对其结构及催化性能所起的作用提供了一定的基础理论数据；采用水相沉淀法在低温条件下成功制备出BiV04的两种纯相,优化了可见光响应的高活性BiVO4的低温制备条件,开拓了BiV04材料的应用途径。为开辟与可见光相匹配的光催化剂的研究与应用以及开发利用绿色光源-太阳能的研究打下一定基础。更多还原

【Abstract】 This paper were committed to study preparation, characterization and photocatalytic properties of nanometer perovskite oxide A(Mg, Ca, Sr)TiO3 and another visible-light photocatalyst vanadate bismuth.Firstly, Nanometer perovskite-type oxides MgTiO3, CaTiO3, SrTiO3 were prepared by sol-gel method. The samples were characterized by thermogravimetry-differential thermal (TG-DTA), X-ray diffraction (XRD), UV-Vis spectrophotometer (UV-Vis) and X-ray photoelectron spectroscopy (XPS). Through the photocatalytic degradation of methylene blue and TCE, photocatalytic activity of the three perovskite-type catalysts was compared. The results showed that different atoms at A metal lead to different crystal structure, and different crystal structure resulted in different temperature of optimum activity. The temperature of best photocatalytic activity for MgTiO3 was 700℃, CaTiO3 and SrTiO3 were 800℃. In the above mentioned catalyst, CaTiO3 had the highest photocatalytic activity. The reason was that CaTiO3 photocatalyst had a greater ability of surface adsorbed oxygen, which provided more surface active species.Secondly, a single crystalline phase monoclinic scheelite type BiVO4 was prepared using Bi(NO3)3·5H2O and NH4VO3 as raw materials by water-phase precipitation method at different calcination temperature. Using methylene blue as a degradation target, we studied that calcination temperature had an impact on visible-light photocatalytic activity of samples. At the same time, molten salt-assisted method was tried to prepare monoclinic BiVO4 to enhance its photocatalytic activity in visible light. The results showed that a single crystalline phase monoclinic scheelite-type BiVO4 was successfully prepared at different calcination temperature(300℃,400℃, 500℃,600℃). The visible-light photocatalytic activity of sample obtained at 400℃was optima. The photocatalytic activity of monoclinic scheelite-type BiVO4 obtained by molten salt-assisted method had been obviously improved, and the amount of molten salt had a significant impact on visible-light photocatalytic activity of BiVO4.Thirdly, single crystalline tetragonal scheelite type BiVO4 and monoclinic scheelite type BiVO4 were prepared using Bi(NO3)3·5H2O and NH4VO3 as raw materials by water-phase precipitation method at low temperature. We studied that pH had an impact on visible-light photocatalytic activity of samples. The results showed that the tetragonal scheelite-type BiVO4 can be obtained by water-phase precipitation method at room temperature, and the monoclinic scheelite-type BiVO4 can be prepared at 110℃. pH had an impact on the crystalline of samples in the low-temperature synthesis process, and neither too acid nor too alkaline conditions are conducive to the formation of monoclinic phase. In the samples prepared at 110℃under different pH, the photocatalytic activity of sample under pH=7 was the highest. The reason was that it had smaller grain size and greater ability of surface adsorbed oxygen.It provides a certain theoretical foundation for the role of A metal in ABO3 perovskite structure photocatalyst by studying structure and photocatalytic properties of perovskite-type oxides A (Mg, Ca, Sr) TiO3. Simultaneously, preparation condition of high visible-light activity BiVO4 at low temperature is optimized, and the application path of BiVO4 material is also developed. The paper lays a stone for expanding research of visible light photocatalyst and utilization of green light source-solar energy.更多还原