【作者】 闵宇霖；

【导师】 俞书宏；

【作者基本信息】 中国科学技术大学 ， 无机化学， 2008， 博士

【摘要】 近年来,核壳纳米结构受到了科学界的广泛关注是因为相对于单一的组分材料,核壳纳米结构材料的物理与化学性质得到了大大的改善。本文主要通过利用碳球和硅球作为模板,使用水热、回流、溶胶—凝胶等简单的化学方法合成出几种氧化物的空心球型结构。探讨了在空心球的制备过程中模板、水热时间和温度、煅烧温度和速度等一系列条件参数对最终产物的形貌及性质的影响作用,取得的研究结果如下:1、通过两步包覆的方法合成了壳层厚度在30—60nm范围可调,金核尺寸在10—40nm可调的含可移动纳米金核的Y₂O₃:Eu³⁺空心球核壳结构,核壳球体的直径可以根据硅球模板的大小在100—1000nm之间调节。此外核壳结构的发射峰的位置在613nm,与传统的Y₂O₃:Eu³⁺块体的吸收峰位置相类似,紫外吸收峰位置蓝移到526nm。这种新颖的核壳结构复合了Y₂O₃:Eu³⁺和Au颗粒的光学性质,再加上其独特的空心球结构,将在生物载体、生物探针等领域有潜在的应用前景。2、通过牺牲碳球模板合成了内含金核的二氧化钛空心球。此空心球的壳层厚度在30—80nm范围可调,纳米金核颗粒在10-40nm范围内可调,核壳球体的直径可以根据碳球模板的大小在100-800nm之间调节。这种新颖的核壳结构相对于单纯的二氧化钛空心球结构和纯P-25商业二氧化钛粉体材料显示出更加良好的光催化效果,能够在3分钟内对亚甲基蓝催化降解率达到40%左右,另外两个对比样品的降解率都在20%以下。另外,空心球结构及内部的金核为分子反应器的构成提供了良好的环境,在生物探测、药物释放等领域具有良好的前景。3、通过牺牲碳球模板法合成了一种结构新颖的含有金、铂纳米颗粒的二氧化硅空心球。此空心球的壳层厚度在30-120nm范围可调,纳米金核颗粒在10-40nm范围内可调,纳米铂颗粒可以在5-60纳米范围内调控,核壳球体的直径可以根据碳球模板的大小在100-800nm之间调节。合成过程利用稍加修改的St（?）ber方法在碳球外壁包覆上二氧化硅层,并利用碳球表面的功能团还原金属盐来控制沉积的金属颗粒的尺寸。这种结构呈现出良好的电催化性质。另外由于其新颖的空心球结构,可能应用于定向药物释放、生物探针、电池材料等领域。更多还原

【Abstract】 Recently, core-shell structures were considered to the hot issue compared to single composite materials because of their great improvement on chemical and physical propriety. In this dissertation, using carbon and silica spheres as sacrificial template, hydrothermal, reflux and sol-gel etc methods were used to synthesize several metal oxide core-shell spheres. A series of parameters such as template, the reaction time and temperature of hydrothermal process and the temperature and velocity of calcinations have been investigated on how they affect the morphology and propriety of ultimate products. The main results can be summarized as follows:1. Anew kind of Au@Y₂O₃:Eu³⁺ hollow spheres with moveable gold nanoparticle core and Y₂O₃:Eu³⁺ as shell have been successfully fabricated via a two-step coating process. The thickness of shell was controlled from 30 to 60nm. The size of Au core was about 10-40nm. The diameter of hollow spheres was controlled from 100-1000nm according to the size of silica template. The Au@Y₂O₃:Eu³⁺ hollow spheres with moveable Au nanoparticle core showed red light emission intensity at 613 nm as that for the Y₂O₃:Eu³⁺ hollow spheres, but are of blue-shifted absorption peak at 526 nm compared with pure Au nanoparticles and Au@SiO₂ core-shell spheres. These new core-shell structures with moveable gold particles have the optical properties of both Au nanoparticles and Y₂O₃:Eu³⁺ phosphor materials, which might have potential applications such as biologic detectors.2. Novel hollow nanospheres of moveable Au particle core/nanoporous titanium oxide particles shell structure have been successfully fabricated via two-step coating processes. The thickness of shell can be controlled in the range of 30 to 80nm. The size of Au core was about 10-40nm. The diameter of hollow spheres can be controlled in the range of 100-800nm according to the size of carbon spheres. This new structure shows excellent photocatalytic properties compared with that of pure TiO₂ hollow spheres and P-25 titanium powders. During three minutes, the degradation rate of methylene blue solution loaded with Au particle core/nanoporous titanium oxide shell structure was about 40%, whereas the other contrasted samples were lower than 20%. Therefore it might provide an efficient way to improve the photocatalytic property of TiO₂.3. Pt nanoparticles embedded silica hollow spheres with moveable Au core have been successfully fabricated via simply templating against Au@carbon spheres. The shell thickness can be controlled from 30 to 120nm. The size of Au core was about 10-40nm. The size of Pt core was about 5-60nm. The diameter of hollow spheres was controlled from 100-800nm according to the size of carbon spheres. Such novel materials shows excellent electrocatalytic properties compared with both typical hollow spheres and pure Pt nanoparticles. This might provide an efficient way to improve the electrocatalytic property of a bulk Pt/GC electrode. In addition, these hollow spheres loaded with noble metal nanoparticels will also find application in the molecule level nanoreactors by taking advantage of their unique hollow structures.更多还原