Yao Fenfa, Xiao Zhangru, Qiao Jingsi, Ji Wei, Xie Rong-Jun, Jin Chuanhong
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Materials, Xiamen University, Xiamen, Fujian 361005, China.
State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, Zhejiang 310027, China.
Nanoscale. 2021 Feb 25;13(7):4133-4139. doi: 10.1039/d0nr08798j.
As symmetry-breaking interfaces, edges inevitably influence material properties, particularly for low-dimensional materials such as two-dimensional (2D) graphene and black phosphorus (BP). Hence, exploiting pristine edge structures and the associated edge reconstruction is important. In this study, we revealed edge reconstruction and evolution in monolayer BP (ML-BP) via in situ high-resolution transmission electron microscopy. Under our typical experimental conditions, spontaneous edge reconstruction occurred in all types of as-prepared edges that include zigzag, Klein zigzag, diagonal, and Klein diagonal edges. Reconstruction induces a periodic variation of the bond length and bond angles of edge atoms: an out-of-plane bending for zigzag and diagonal edge atoms and a dimerization for two neighboring edge atoms on the Klein edge, respectively. Surface atom diffusion can also induce edge structural evolution as evidenced by the atomic scale dynamics captured for the zigzag edge. Experimentally resolved edge configurations and reconstruction were further corroborated by ab initio first-principles calculations. This study explores the understanding of the edge stability in 2D BP materials and may provide routes for precisely controlled edge structure engineering.
作为打破对称性的界面，边缘不可避免地会影响材料特性，特别是对于诸如二维（2D）石墨烯和黑磷（BP）等低维材料。因此，探索原始边缘结构以及相关的边缘重构具有重要意义。在本研究中，我们通过原位高分辨率透射电子显微镜揭示了单层BP（ML-BP）中的边缘重构和演化。在我们的典型实验条件下，在所有类型的制备边缘（包括锯齿形、克莱因锯齿形、对角线形和克莱因对角线形边缘）中均发生了自发的边缘重构。重构会导致边缘原子的键长和键角发生周期性变化：锯齿形和对角线形边缘原子分别发生面外弯曲，而克莱因边缘上的两个相邻边缘原子发生二聚化。表面原子扩散也会引发边缘结构演化，锯齿形边缘捕获的原子尺度动力学证明了这一点。实验解析的边缘构型和重构通过从头算第一性原理计算得到了进一步证实。本研究探索了对二维BP材料中边缘稳定性的理解，并可能为精确控制边缘结构工程提供途径。
