金属氧化物介孔及纳米复合材料的合成

【作者】 沈晚晴；

【导师】 周亚明；

【作者基本信息】 复旦大学 ， 无机化学， 2011， 硕士

【摘要】 金属氧化物因其在工业上广阔的应用前景而被广泛研究,其中关于氧化铝和氧化钛的研究备受瞩目。氧化铝具有良好的机械强度、较高的热稳定性和化学稳定性、适宜的等电点、可调变的表面酸碱性等优点,在陶瓷、耐火材料、医药、吸附、催化等领域有着重要应用。二氧化钛是一种低价、低毒性的半导体材料,在光催化、染料敏化太阳能电池等方面具有广泛的应用。介孔材料具有大的比表面积和孔体积,均一且在纳米尺寸上连续可调的孔径,介孔金属氧化物在大分子吸附、分离、化学传感器、光电磁、化工催化等领域展现出了无可以拟的优越性和广阔的应用前景。本论文研究了有序介孔氧化铝、介孔氧化铝-氧化钛复合物,以及金纳米粒子/二氧化钛复合物的合成,具体研究内容如下：论文第二章利用“酸碱对”方法,以廉价的无机铝盐为“酸源”,铝醇盐为“碱源”,通过溶剂挥发诱导自组装合成得到有序介孔Al2O3。通过调节前驱体酸碱对的比例,采用不同的铝前驱体,不同的表面活性剂,成功得到了一系列具有较大孔径,较高比表面积,具有二维六方结构的高度有序介孔Al2O3,且在800℃煅烧晶化后介观结构仍能保持。通过调节铝源前驱体酸碱对的比例,改变酸源、碱源、表面活性剂,考察这些参数对样品有序性和结构参数的影响。不同酸碱对比例中,Al(NO3)3:AlPO=5:5的条件下得到的A1203有序性最好,比表面积最高,达到311m2/g。AIC13为酸源时,AlC13:AlPO=5:5条件下得到的Al2O3孔径最大,达到11.5nm。与之前的报道相比,在使用P123为表面活性剂的情况下,我们得到了高度有序且具有最大孔径的介孔氧化铝材料。论文第三章在第二章工作的基础上,利用“酸碱对”方法,以廉价的硝酸铝和钛酸正丁酯分别作为“酸源”和“碱源”,通过溶剂挥发诱导自组装合成介孔氧化铝-氧化钛复合物。通过调节前驱体酸碱对的比例,调变溶剂挥发的温度,得到系列不同钛铝比,具有蠕虫状介孔孔道结构,孔径分布均一的介孔复合氧化物,不同材料孔径约在6～11nm之间。与介孔纯TiO2材料相比,比表面积提高,不同条件下得到的复合材料最高比表面积达到244m2/g。通过高温煅烧考察了Al2O3-TiO2复合物的晶化过程,发现Al2O3-TiO2复合物降低了A1203的结晶温度(700℃),升高了TiO2的锐钛矿结晶温度(>400℃和由锐铁矿向金红石晶型转变的温度(900℃),提高了TiO2的热稳定性。论文第四章通过一步溶胶-凝胶过程,以光诱导的方法在二氧化钛凝胶单片中,合成了金纳米粒子。这是首次报道光诱导还原AuCl4离了为金纳米粒子的过程在氧化钛溶胶阶段而非凝胶化之后进行,实验证明该方法可以在最终形成的氧化钛凝胶中得到高分散、直径约8nm、尺寸均一的金纳米粒子,且表面等离子共振(SPR)吸收带会蓝移至578nm。更多还原

【Abstract】 Metal oxides are largely studied because of their almost limitless potential in a number of industrial applications. Among metal oxides alumina and titania are.very popular for their unique properties and diverse applications. Alumina has numerous applications ranging from catalysis, to optics, electronics and biomedicine. Titania is a chemically stable, non-toxic and environmentally friendly oxide and it has been intensely investigated in photocatalysis and dye-sensitized solar cell and so on.With the characteristics of mesoporous materials, such as highly uniform channels, large surface area, narrow pore-size distribution, tunable pore sizes over a wide range, and so on, metal oxides with a mesostructure should possess much more excellent properties for their applications.In this thesis, we studied the synthesis of ordered mesoporous alumina, mesoporous alumina-titania and gold nanoparticles/titania composites.In chapter 2, we use inorganic aluminum salt and aluminum alkoxides as precursor to synthesize highly ordered mesoporous alumina by "acid-base pair" method through the evaporation-induced self-assembly (EISA) process. By changing experiment parameter such as mol ratio of precursors, different precursors and surfactants, we successfully get mesoporous alumina with a highly ordered 2D hexagonal mesostructure, high surface area(31 1m2/g, Al(NO3)3:AlPO=5:5), large pore volume and pore size(11.5nm, AlC13:AlPO=5:5), which is resistant to high temperature up to 800℃.In chapter 3, mesoporous alumina-titania composite are synthesized by "acid-base pair" method through the evaporation-induced self-assembly (EISA) process. The effect of the mol ratio of the "acid-base pair" and EISA temperature are investigated on the mesostructures and crystalline. The series of composites have worm-like mesostructures, uniform pore size distribution(6～11nm) and higher surface area(244 m2/g) compared with pure mesoporous titania. It is found that the crystallization temperature of alumina decreases in the mesoporous alumina-titania composites(700℃). while the crystallization and crystalline transformation temperature of titania increase(>400℃and (900℃). which indicating that the thermal stability of titania is improved.In chapter 4, spherical gold nanoparticles with diameters less than 8 nm have been prepared by the photoinduced reduction via a one-step sol-gel process. The Au nanoparticles are highly dispersed in a TiO2 gel monolith with a surface plasmon resonance absorption band centered at 578 nm.. We demonstrated for the first time that the photoinduced reduction of AuCl4- ions in the sol stage instead of after the gel formation could guarantee the uniformity of the size(8nm), shape, and dispersion of Au nanoparticles in the ultimately formed TiO2 gel.更多还原