Ag表面对聚乙烯吡咯烷酮的吸附及纳米结构表面选择机制

Adsorption of polyvinylpyrrolidone on Ag surface and mechanism of selective growth of Ag nanostructures

摘要:

为了查明Ag纳米线的选择形成机制以及与表面活性剂之间的相互作用，本文采用了基于密度泛函理论的第一性原理方法研究了不同Ag晶面结构在聚乙烯吡咯烷酮（PVP）体系中稳定性及吸附影响. 结果表明: PVP分子体系严重影响不同Ag晶面结构的稳定性，对Ag（200）和Ag（111）晶面结构具有选择性. 此外，随着PVP分子聚合度的增加，PVP与Ag（200）晶面的结合比Ag（111）更强，这有助于Ag（200）纳米结构的形成. 从分子和原子角度查明了长链PVP分子对Ag纳米结构的调控机制主要受PVP分子中的酮基氧与表面Ag原子之间的成键作用，以及PVP与Ag（200）表面之间的范德华力的影响.

Abstract:

To elucidate the mechanism of selective growth of Ag nanowires in capping agents, we investigated and the interaction between polyvinylpyrrolidone (PVP) molecules and various Ag crystal surfaces by first-principles calculations. The results show that PVP molecules severely affect the stability of Ag surfaces. Only Ag (200) and Ag (111) facets well maintain their structures upon the absorption of PVP molecules, suggesting their preferential growth in this capping agent. With the increase of PVP concentration, the binding of PVP molecules to the Ag (200) facet becomes stronger than that of Ag (111), which may facilitate the formation of Ag (200) nanostructure. The regulation mechanism of long-chain PVP molecules on Ag (200) nanostructures is mainly governed by the van der Waals force as well as the chemical bonding between ketone oxygen and Ag atoms.