Theoretical Predictions of Freestanding Honeycomb Sheets of Cadmium Chalcogenides
Theoretical Predictions of Freestanding Honeycomb Sheets of Cadmium Chalcogenides
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DOI：
10.1021/jp504299e
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发表时间：
2014-06
影响因子：
3.7
通讯作者：
Jia Zhou;Jingsong Huang;B. Sumpter;P. Kent;Yu Xie;H. Terrones;Sean C. Smith
中科院分区：
文献类型：
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作者：
Jia Zhou;Jingsong Huang;B. Sumpter;P. Kent;Yu Xie;H. Terrones;Sean C. Smith
采用胶体合成法生长了二维(2D)纳米晶Cd_x(X=S，Se，Te)，并在其表面包裹了有机配体。最近关于锌硒的实验工作表明，有机配体可以在高温下被移除，得到独立的二维锌硒薄膜。在这项理论工作中，通过切割闪锌矿(ZB)和纤锌矿(WZ)相的所有可能的晶格面，考虑了独立的单层到几层的CDX片材，每个片材都具有伪蜂窝晶格。利用密度泛函理论，系统地研究了它们的几何结构、能级和电子性质。发现所有层状片都发生了强烈的表面变形，但所有的伪蜂窝晶格都被保留了下来，从而产生了独特的表面波纹和不同的电子性质。结合声子模计算和分子动力学模拟的能量学结果表明，这些独立的二维膜的合成可以作为一种新型的分子动力学方法。
Two-dimensional (2D) nanocrystals of CdX (X = S, Se, Te) typically grown by colloidal synthesis are coated with organic ligands. Recent experimental work on ZnSe showed that the organic ligands can be removed at elevated temperature, giving a freestanding 2D sheet of ZnSe. In this theoretical work, freestanding single- to few-layer sheets of CdX, each possessing a pseudo honeycomb lattice, are considered by cutting along all possible lattice planes of the bulk zinc blende (ZB) and wurtzite (WZ) phases. Using density functional theory, we have systematically studied their geometric structures, energetics, and electronic properties. A strong surface distortion is found to occur for all of the layered sheets, and yet all of the pseudo honeycomb lattices are preserved, giving unique types of surface corrugations and different electronic properties. The energetics, in combination with phonon mode calculations and molecular dynamics simulations, indicate that the syntheses of these freestanding 2D sheets could ...