电位控制ZnO/表面活性剂复合多层膜在固/液界面上的自组装

Potential Controlled Self-assembly of ZnO-surfactant Hybrid Multilayers on Solid-liquid Interface

通过控制固/液界面电极电位的方式,控制表面活性剂和金属离子在电极表面的自组装,制备出了高度取向的ZnO/表面活性剂复合多层膜.对无机层形态和结构进行了分析,并采用X射线反射率和X射线漫散射研究了电极电位控制下ZnO/表面活性剂复合多层膜在固/液界面的自组装生长.结果表明,在一定电位下,只有当表面活性剂浓度低于其饱和吸附浓度时,采用阶跃电位沉积方式才能明显改变复合薄膜的周期厚度;恒电位沉积方式控制电极电位时,随着沉积电位的提高,多层膜层状结构由一组层状相变为多组层状相,同时层状结构的取向变差.实验研究结果验证了电化学自组装过程是由金属离子的还原速度和表面活性剂的吸附速度二者共同控制完成的.

We synthesized highly oriented zinc oxide-surfactant muhilayers on silicon substrates from Zn（NO3）2 solutions containing extremely low concentration of sodium dodecyl sulfate. The structure of the muhilayers was investigated by X-ray photoelectron spectrum, X-ray technologies and scan electron microscopy. Two methods were used to control the electrode potential. The resuhs show that in the multi-potential step deposition mode one can change the period of the lamellar structure only when the concentration of the surfacrant is below the saturated concentration at the corresponding potential. In the potentiostatic deposition＇mode, the films exhibit well-defined and homogeneous lamellar structure only at low potential. All the results indicate that the assembly of the surfactant molecules and metal ions on the solid-liquid interface is determined by the electrode potential, which controls the relative speed of the reduction of the zinc ions and the aggregation of the surfactant.