弱酸介质中介孔Zr-SiO_2的合成及形貌控制

直接在介孔SiO_2中掺杂金属Zr不是十分容易,这主要是由于在强酸介质中,Zr往往不能与Si源一起共缩合而被沉积到介孔SiO_2骨架中。因此,本文采用原位一步合成法,在含有模板剂、盐酸、醋酸锌的弱酸性水溶液中添加Si源和Zr源,通过原位共沉积,直接制备出具有介孔结构的Zr-SiO_2材料。研究结果表明:当合成母液中Zr与Si的摩尔比r≤0.2∶1时,所得样品具有高度有序的介孔结构;继续增加Zr的添加量(r=0.3或0.5)会使有序孔的规整性下降。随着合成体系中r从0.01变化到0.2,样品晶胞参数由9.7nm增加到10.9nm,孔壁厚度由1.4nm增大到2.6nm,证明了Zr对介孔SiO_2骨架的有效掺杂。通过改变样品中的Zr掺杂量还可以调控所得Zr-SiO_2材料的形貌,获得具有蠕虫状、葡萄状和麦粒状等形状规整的粒子。介孔Zr-SiO_2材料在去除水体中有机染料亚甲基蓝中表现出良好的性能。

Synthesis and morphology control of mesoporous Zr-SiO2 under mildly acidic conditions

It is not very easy to directly dope Zr into the mesoporous SiO2 .This is due to Zr species are generally difficult to co-condensation with siliceous species and then be co-incorporated into the framework of the SiO2 under strong acidic conditions.Therefore,a series of mesoporous Zr-SiO2 were successfully synthesized by a one-step method in the mildly acidic solutions that contain surfactant,hydrochloride acid,zinc acetate,siliceous and zirconi-um species.Experimental results show that all Zr-SiO2 samples synthesized with the Zr:Si molar ratio (r)equal to or less than 0.2:1 have the well-ordered mesostructures.The integrity of the mesostructure will decrease if further increase the r to 0.3 or 0.5.When the r in the initial reaction solution changes from 0.01 to 0.2,the cell parameter of the corresponding obtained material increases from 9.7 to 10.9 nm,and the wall thickness of the Zr-SiO2 sample also enlarges from 1.4 to 2.6 nm,respectively.This confirms that Zr species are incorporated into the framework of mesoporous SiO2 .The morphology of the Zr-SiO2 can be controlled by the incorporation of different amounts of Zr species.The highly regular fine particles with morphologies such as wormlike,grape-like and wheat grain-like are then obtained for the Zr-SiO2 samples.The mesoporous Zr-SiO2 materials present high adsorption abilities in the re-moval of methylene blue dye from aqueous solutions.