硅醇在含羟基K_2Ti_6O_(13)(010)表面吸附特性的第一性原理研究

First-principles Investigation of Silanol Adsorption on K_2Ti_6O_(13)(010) Surface with Hydroxy

采用基于密度泛函理论的第一性原理计算方法对H2O分子诱生的羟基在六钛酸钾K2Ti6O13(010)表面的形成过程及其对硅醇在K2Ti6O13(010)表面吸附性能的影响及机理进行研究。结果表明:引入的单个H2O分子在K2Ti6O13(010)表面可自发分解为OH-和H+,两者会分别与表面的Ti及其近邻的O结合,进而在表面形成两个羟基;羟基的存在会使硅醇在K2Ti6O13(010)表面实现由物理吸附至化学吸附的转变,极大地增强了硅醇与K2Ti6O13表面的结合强度,很好地解释了实验现象;电子结构分析表明,羟基改善硅醇在K2Ti6O13表面结合强度的根源应归因于羟基与硅醇中的O sp轨道电子的贡献。

Using first-principles calulations method based on density functional theory（DFT）,the formation of H2O-induced hydroxy on K2Ti6O13（010） surface and its influences on the adsorption properties of silanol on K2Ti6O13 surface were investigated.It is found that single H2O molecule is ready to dissociate into OH-and H＋ spontaneously.The two ions combine with Ti atom and its neighbor O atom on K2Ti6O13（010） surface respectively,which induces the formation of two hydroxies on the surface.The adsorption characteristic of silanol on K2Ti6O13（010） surface changes from physical adsorption to chemical adsorption due to the existence of hydroxy,and enhances significantly the bonding strength between silanol and K2Ti6O13 surface.The calculated results interpret well experimental phenomena.Analysis of the electronic structures shows that the inherent reason of the enhanced bonding strength between silanol and K2Ti6O13 surface should be attributed to the contributions of O sp orbitals involved in hydroxy and silanol.