State Key Laboratory of Heavy Oil Processing , China University of Petroleum , Beijing 102249 , P. R. China.
School of Applied and Engineering Physics , Cornell University , Ithaca , New York 14850 , United States.
ACS Appl Mater Interfaces. 2018 Oct 10;10(40):34401-34408. doi: 10.1021/acsami.8b13428. Epub 2018 Sep 25.
Semimetallic-layered transition-metal dichalcogenides, such as TiS, can serve as a platform material for exploring novel physics modulated by dimensionality, as well as for developing versatile applications in electronics and thermoelectrics. However, controlled synthesis of ultrathin TiS in a dry-chemistry way has yet to be realized because of the high oxophilicity of active Ti precursors. Here, we report the ambient pressure chemical vapor deposition (CVD) method to grow large-size, highly crystalline two-dimensional (2D) TiS nanosheets through in situ generating titanium chloride as the gaseous precursor. The addition of NHCl promoter can react with Ti powders and switch the solid-phase sulfurization reaction into a CVD process, thus enabling the controllability over the size, shape, and thickness of the TiS nanosheets via tuning the synthesis conditions. Interestingly, this semimetallic 2D material exhibits near-infrared surface plasmon resonance absorption and a memristor-like electrical behavior, both holding promise for further application developments. Our method hence opens a new avenue for the CVD growth of 2D metal dichalcogenides directly from metal powders and pave the way for exploring their intriguing properties and applications.
层状半金属过渡金属二卤化物，如 TiS，可以作为一个平台材料来探索由维度调制的新物理现象，以及在电子学和热电学中开发多功能应用。然而，由于活性 Ti 前体的高亲氧性，在干燥化学条件下控制合成超薄 TiS 尚未实现。在这里，我们通过原位生成二氯甲烷作为气态前体，报告了在常压化学气相沉积（CVD）方法中生长大尺寸、高结晶二维（2D）TiS 纳米片。添加 NHCl 促进剂可以与 Ti 粉反应，并将固相硫化反应转变为 CVD 过程，从而可以通过调整合成条件来控制 TiS 纳米片的尺寸、形状和厚度。有趣的是，这种半导体 2D 材料表现出近红外表面等离子体共振吸收和类忆阻器的电行为，这都为进一步的应用发展提供了前景。我们的方法为从金属粉末直接 CVD 生长二维金属二卤化物开辟了新途径，并为探索它们有趣的性质和应用铺平了道路。
