吸附法原位制备Ag/SiO_2纳米复合材料  

Synthesis of Ag/SiO_2 nanocomposite material by adsorption phase nanoreactor technique

作　　者：毛从文[1] 蒋新[1] 

机构地区：[1]浙江大学材料与化学工程学院,杭州310027

出　　处：《复合材料学报》2006年第4期88-94,共7页Acta Materiae Compositae Sinica

基　　金：国家自然科学基金(20476088);浙江省科技计划项目(2005C310027)

摘　　要：以纳米SiO2为载体,以其富集水的表面吸附层作为纳米反应器制备了Ag纳米粒子,研究了水浓度对吸附和反应的影响。体系中NaOH加入量一定的条件下,硅胶表面NaOH的平衡吸附量随着水浓度(0、0.05%、0.10%、0.25%、0.50%、1.00%)的增加而增加,且存在两个突变区域(由0增至0.05%和由0.25%增至0.50%)。通过XRD、TEM分析发现生成的银粒子(或氧化银)团聚现象随水浓度的增加而逐渐减弱,在硅胶表面分布越来越均匀,晶粒粒径也逐渐减小。当水浓度约为0.50%时,生成的Ag或Ag2O粒子粒径多数在5 nm以下,且均匀分布在SiO2表面。根据Ag+的还原机理和吸附过程基本原理,认为吸附水层的形成导致生成Ag粒子的反应场所由硅胶表面转移到吸附水层中,造成了Ag粒子形貌的变化。Ag nanoparticles were synthesized in a nanoreactor formed by an adsorption layer on the silica surface. The effects of concentration of water on the process of adsorption and reaction were analyzed. When the mass fraction of NaOH keeps constant, the equilibrium content of NaOH adsorbed on SiO2 increases with the increase of concentration of water, which changes from 0 to 1.00%. Two jump regions of equilibrium content are found from 0 to 0.05% and from 0. 25% to 0.50%. Analysis by XRD and TEM indicates that the agglomeration of Ag or Ag2O particles becomes more moderate, its dispersion on the surface SiOz becomes more uniform, and its grain size becomes smaller with the increase of concentration of water. The minimum grain size and uniform dispersion can be achieved when the concentration of water is 0.50%. Based on the reduction mechanism of Ag＋ and essential principle of the adsorption process on the surface of SiO2, it can be concluded that the water-rich adsorption layer on the surface of SiO2 is formed gradually with the increase of water concentration and the region of Ag generation changes from the surface of SiO2 to the water-rich adsorption layer, where the concentration of NaOH is so high that most of Ag are generated in it.

关 键 词：吸附层 Ag/SiO2 过程机理 反应控制 

分 类 号：TB332[一般工业技术—材料科学与工程] O614[理学—无机化学]