Semimetallic-layered transition-metal dichalcogenides, such as TiS₂, 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 TiS₂ 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) TiS₂ nanosheets through in situ generating titanium chloride as the gaseous precursor. The addition of NH₄Cl 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 TiS₂ 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.

中文翻译：

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原位生成的挥发性前体用于半金属2D二硫属元素化物的CVD生长

半金属层状过渡金属二硫化碳（例如TiS ₂）可用作研究受尺寸调制的新型物理方法以及开发电子和热电学通用应用程序的平台材料。然而，由于活性Ti前体的高亲氧性，以干化学方式控制超薄TiS _2的合成尚待实现。在这里，我们报告的环境压力化学气相沉积（CVD）方法通过原位生成氯化钛作为气态前体来生长大尺寸，高结晶度的二维（2D）TiS ₂纳米片。NH _4的添加Cl促进剂可以与Ti粉末反应，并将固相硫化反应转换为CVD工艺，从而可以通过调节合成条件来控制TiS ₂纳米片的尺寸，形状和厚度。有趣的是，这种半金属2D材料表现出近红外表面等离子体激元共振吸收和类似忆阻器的电性能，两者都为进一步的应用开发提供了希望。因此，我们的方法为直接从金属粉末中2D金属二卤化物的CVD生长开辟了一条新途径，并为探索其有趣的性能和应用铺平了道路。