A Case Study on the Mechanisms of the Nucleation and Growth of Silicene on the Surface of Calcium Silicate Hydrates-中国材料进展

文章信息/Info

作者:: ZHOU Yang1; 2; ZHENG Haojie1; QIU Yuwen1; ZOU Xixi1; HUANG Jiale1; (1. School of Materials Science and Engineering, Southeast University, Nanjing 211189, China) （2. State Key Laboratory of High Performance Civil Engineering Materials, Jiangsu Research Institute of Building Science Co, Ltd, Nanjing 211103, China)

Author(s):: 周扬1; 2; 郑浩杰1; 邱钰雯1; 邹茜茜1; 黄家乐1; （1.东南大学材料科学与工程学院，江苏南京 211189）（2.江苏省建筑科学研究院有限公司高性能土木工程材料国家重点实验室，江苏南京 211103）

关键词:: silicene; calcium silicate hydrates; molecular dynamics; nucleation; growth

摘要:: Silicene, a newly emerging twodimensional (2D) material, can be a superior reinforcement candidate to enhance the mechanical performance of calcium silicate hydrates (C-S-H, the primary hydration product of portland cement), in consideration of the common substrate atom Si. Here, with the reactive molecular dynamics simulations, the possibility of depositing such a silicene monolayer on the C-S-H surface was investigated. The results indicate that high-reactivity non-bridging oxygen atoms (NBOs) on the C-S-H surface facilitates the nucleation of silicon atoms, by the formation of high-strength Si-O-Si bonds. The nucleated silicon clusters follow a relatively uniform distribution over the whole surface. As the deposition continues, clusters grow larger, leading to the merging and coalescences of neighboring ones, via the formation of bridging bonds and the transformation of cluster shape. Eventually, a relatively complete silicene monolayer has been successfully established on the C-S-H surface, with high surface coverage ratio. Furthermore, it suggests the deposition rate and temperature may substantially affect the nucleation and growth process of silicene. This study opens the perspective of depositing a 2D material on an inorganic matrix and elucidates the atomic stacking mechanism on the interfaces.

Abstract:: 硅烯作为一种新兴二维材料，与水化硅酸钙（C-S-H，硅酸盐水泥最主要的水化产物）同为硅质基底材料，将其与水化硅酸钙复合或能有效提高水化硅酸钙的韧性。基于分子动力学模拟技术，探索了单层硅烯在水化硅酸钙表面成核生长的可能性。模拟结果显示，通过与沉积硅原子形成高强度的Si-O-Si键，水化硅酸钙表面的高反应活性非桥接氧原子（NBOs）促进了硅原子团簇的成核，已成核的硅原子团簇在水化硅酸钙表面均匀分布。随着硅原子的进一步沉积，已成核的硅原子团簇进一步生长，通过桥接键的形成和团簇形状的改变，相邻的小团簇发生合并，形成大团簇。最终，一片较为完整的单层硅烯在水化硅酸钙表面生长出来，且表面覆盖率高。在上述过程中，硅原子的沉积速率以及沉积温度对硅烯的成核和生长过程具有一定的影响。该研究为无机材料表面沉积二维材料开辟了前景，并揭示了其界面处的原子堆积机制。