摘要
We report a new and convenient strategy for incorporating fluorescent semiconductor nanocrystals into silica hosts for the synthesis of multifunctional nanostructures. Mesoscale porosity was first created in conventional St?ber silica spheres by chemical etching under the protection of polymeric ligands. Uniform and highly luminescent Cd Se nanocrystals were then directly grown in the porous silica network by reacting the silica spheres in a growth solution at high temperature. The confinement of silica network led to slower nanocrystal growth and subsequently smaller Cd Se dots with blue shifted fluorescence compared with those without confinement. The loading number of Cd Se nanocrystals can be easily tuned by changing the degree of porosity of the silica. The advantages of this strategy include simplicity as no special surface treatment processes are needed, general applicability to silica hosts of various shapes and sizes, high flexibility in tuning the dimensions of both the active nanocrystals and host particles, and ample opportunities for incorporating multiple functionalities. With the demonstration of a porous Fe3O4@Si O2/Cd Se composite structure with combined magnetic and optical properties, we believe this strategy may provide a platform for the fabrication of a large variety of multifunctional composite nanostructures.
本文报道了一种新颖且便捷的将荧光半导体纳米晶包覆到二氧化硅球中进而制备多功能纳米结构的方法.从溶胶凝胶法合成二氧化硅微球开始,在聚合物配体保护下进行化学刻蚀从而获得介孔级孔道,然后将带有孔道的二氧化硅微球投入到制备Cd Se量子点的高温反应体系中,就可以直接在二氧化硅微球的孔道中生长尺寸均匀且具有高荧光产率的Cd Se纳米晶.研究发现二氧化硅微球中的孔道对于Cd Se量子点的生长有一定的抑制作用,因此与自由生长的量子点比较其荧光光谱会发生蓝移,二氧化硅微球中负载Cd Se量子点的数量可以通过选择不同刻蚀程度的二氧化硅微球来实现.这种纳米结构优点在于:不需要特殊的表面处理工艺,对于不同形貌及尺寸的二氧化硅微球具有普适性,对于纳米晶与主体材料的尺寸调控具有较高的灵活性,并且可以同时包裹其他功能材料,比如将磁性纳米粒子引入到该体系,合成了兼具磁学与光学性能的Fe3O4@Si O2/Cd Se复合纳米结构材料.该方法为制备多功能复合纳米结构材料提供了一个平台.
基金
supported by the US National Science Foundation (DMR-0956081)
the fellowship support by the China Scholarship Council (CSC)
supported by the Office of Science, Office of Basic Energy Sciences,of USA Department of Energy under Contract No DE-AC02-05CH11231
