Ag-Cu双金属纳米颗粒在硅酸盐玻璃中的形成过程

FORMATION PROCESSES OF Ag-Cu BIMETALLIC NANOPARTICLES IN SILICATE GLASS

利用两步离子交换结合H_2气氛热处理的方法,制备出Ag-Cu双金属纳米颗粒/硅酸盐玻璃复合材料。结合吸收光谱和X射线光电子能谱研究了不同工艺条件下Ag、Cu在玻璃中的深度分布、价态变化及其玻璃网络结构的变化。结果表明:掺杂后的玻璃中银和铜的含量随深度不同有所不同。Ag^+-Na^+离子交换过程中,Ag^+与非桥氧结合形成Si—O—Ag键,样品中的银主要以离子状态存在。H_2气氛中热处理后,大部分与非桥氧相连的Ag^+被还原,H^+随即取代Ag^+位置,与非桥氧形成—OH结构,还原出来的Ag^0经成核和生长形成银纳米颗粒。第二次Cu^+-Na^+离子交换后,Cu^+被引入硅酸盐玻璃,并有二价铜离子存在,再经过H_2热处理后,铜离子被还原,在表层聚集生成铜纳米颗粒。

Ag-Cu bimetallic nanoparticles/silicate glass composite materials were fabricated by two times of ion-exchange and subsequently thermal treatment in H2 atmosphere. Optical absorption spectroscopy and X-ray photoelectron spectroscopy were used to study the depth profiles, the valence states of silver and copper atoms in silicate glass and the change of glass network structure. The results show that the atomic concentration of silver and copper atoms in the glass matrix changes with the depth. In the process of Ag^＋-Na^＋ ion-exchange, the exchanged Ag ion bonds with a non-bridging oxygen into a Si-O-Ag structure. During thermal treatment in H2 atmosphere, most of the Ag ions are reduced into neutral Ag atoms by H2, and the H^＋ will occupy the reduced Ag^＋ places to form hydroxyl groups. The reduced silver atoms nucleate and grow into silver nanoparticles in the glass matrix. During the secondary Cu^＋ for Na^＋ ion-exchange process, copper ions are introduced into the glass matrix and there exist a few divalent copper ions. After subsequently thermal treatment in H2 atmosphere, copper ions are reduced into neutral copper atoms, which nucleate and grow into copper nanoparticles.