Department of Chemistry, Yonsei University, Seoul 120-749, Korea.
J Am Chem Soc. 2013 Mar 13;135(10):3736-9. doi: 10.1021/ja309744c. Epub 2013 Mar 4.
Two-dimensional (2D) layered nanostructures are emerging fast due to their exceptional materials properties. While the importance of physical approaches (e.g., guest intercalation and exfoliation) of 2D layered nanomaterials has been recognized, an understanding of basic chemical reactions of these materials, especially in nanoscale regime, is obscure. Here, we show how chemical stimuli can influence the fate of reaction pathways of 2D layered nanocrystals. Depending on the chemical characteristics (Lewis acid ((1)O2) or base (H2O)) of external stimuli, TiS2 nanocrystal is respectively transformed to either a TiO2 nanodisc through a "compositional metathesis" or a TiO2 toroid through multistage "edge-selective structural transformation" processes. These chemical reactions can serve as the new design concept for functional 2D layered nanostructures. For example, TiS2(disc)-TiO2(shell) nanocrystal constitutes a high performance type II heterojunction which not only a wide range solar energy coverage (~80%) with near-infrared absorption edge, but also possesses enhanced electron transfer property.
二维（2D）层状纳米结构因其独特的材料性能而迅速发展。虽然已经认识到物理方法（例如客体插层和剥离）在 2D 层状纳米材料中的重要性，但对这些材料的基本化学反应的理解，特别是在纳米尺度上，仍然不清楚。在这里，我们展示了化学刺激如何影响 2D 层状纳米晶体反应途径的命运。根据外部刺激的化学特性（路易斯酸（(1)O2）或碱（H2O）），TiS2 纳米晶体分别通过“组成交换”转化为 TiO2 纳米盘，或通过多步“边缘选择性结构转化”过程转化为 TiO2 toroid。这些化学反应可以作为功能性 2D 层状纳米结构的新设计概念。例如，TiS2（圆盘）-TiO2（壳）纳米晶体构成了高性能 II 型异质结，不仅具有宽范围的太阳能覆盖（~80%）和近红外吸收边缘，而且还具有增强的电子转移性能。
