银纳米粒子在聚苯乙烯球表面的异相成核与生长

Investigation of heterogeneous nucleation-and-growth of silver nanoparticles on polystyrene spheres

采用原位化学还原法,将银纳米颗粒直接沉积到没有进行任何活化处理的聚苯乙烯(Polysty-rene,PS)亚微米球的表面.运用X射线衍射(XRD)、透射电子显微观察(TEM)和X射线能谱(EDS)等分析手段对产物的成分、形态、尺寸、以及分布等特征进行了详细表征.结果表明,产物为大量均匀的PS-Ag复合粒子,银纳米粒子以带状为主,并沿着球形基体的弧形表面不连续分布.高分辨电子显微分析(HRTEM)表明,银粒子均为结晶度较高的单晶,它们与非晶PS球形基体之间结合的很好,这应归因于银在基体表面的异相成核及沿着与球面切向方向的生长.此外,研究了反应物浓度、温度等因素对银纳米粒子在PS球表面沉积的影响.根据实验结果,详细探讨了原位化学还原过程中银纳米粒子在非晶PS球表面的异相成核与生长的机理.

Using an in-situ chemical reduction method, silver nanoparticles （NPs） were directly deposited onto the surfaces of polystyrene （PS） submicron spheres, without the activation by additional ＂seed metals＂, to fabricate PS -- Ag composite particles. The size, morphology and distribution of silver NPs on PS spheres were studied detailedly with transmission electron microscopy （TEM） and energy dispersive X--ray spectroscopy （EDS） techniques. It is found that the PS spheres are coated with relatively homogeneously and discontinuously distributed Ag NPs of beh- like shapes. Resolution transmission electron microscopy （HRTEM） analysis shows that there is a relatively stable interfacial coalescence between metallic sing-crystalline Ag and amorphous PS supports. The concentration of rea- gents and reaction temperatures were found to be key factors for immobilization of silver NPs. Heterogeneous nucle- ation-and-growth of silver particles on PS spheres were studied on the basis of the experimental results.