Wang Zhenxuan, Chen Xiaobing, Chen Min, Wu Limin
Department of Materials Science and Advanced Materials Laboratory, Fudan University, Shanghai 200433, China.
Langmuir. 2009 Jul 7;25(13):7646-51. doi: 10.1021/la9002934.
Hollow Ag/SiO2 double-shelled spheres with silver nanoparticle coating onto the interior wall of hollow silica have been successfully prepared via a novel and facile approach. In this method, negatively charged polystyrene (PS) beads were first modified by Sn2+ ions via electrostatic interaction, and then by Ag+ ions, which were reduced by Sn2+ ions and sodium-potassium tartrate to obtain PS/Ag composite spheres. When these spheres were coated by silica nanoparticles as shells from the hydrolysis and condensation reaction of tetraethoxysilane (TEOS) in isopropanol/ammonia mixture at 15 degrees C, the PS beads were "dissolved" in the same medium subsequently even synchronously, directly forming hollow Ag/SiO2 double-shelled spheres. Neither additional dissolution nor calcination process was used to remove polymer templates. This structure of hollow spheres not only has high catalytic activity, but also will decrease the loss of Ag nanoparticles due to frictional and/or other mechanical forces and the possible aggregations, and have controllable and selective catalytic activity compared to these common nanocomposite spheres with noble metal nanoparticles coating on the surfaces of supporting beads.
通过一种新颖且简便的方法，成功制备了在内壁涂覆有银纳米颗粒的中空Ag/SiO₂双壳球。在该方法中，首先通过静电相互作用用Sn²⁺离子对带负电的聚苯乙烯（PS）珠进行改性，然后用Ag⁺离子改性，Ag⁺离子被Sn²⁺离子和酒石酸钠钾还原以获得PS/Ag复合球。当这些球在15℃下由四乙氧基硅烷（TEOS）在异丙醇/氨混合物中的水解和缩合反应作为壳被二氧化硅纳米颗粒包覆时，PS珠随后甚至同步地在同一介质中“溶解”，直接形成中空Ag/SiO₂双壳球。无需额外的溶解或煅烧过程来去除聚合物模板。这种中空球结构不仅具有高催化活性，而且由于摩擦和/或其他机械力以及可能的聚集，将减少Ag纳米颗粒的损失，并且与这些在支撑珠表面涂覆有贵金属纳米颗粒的普通纳米复合球相比，具有可控和选择性的催化活性。
