Due to its nontoxicity, suitable bandgap, high defect tolerance and high electron mobility, layered BiI 3 has been gaining attention in photoelectric device and nonlinear optics field. However, the growth of large-size single crystal 2D BiI 3 has not been achieved. Herein, the synthesis of single crystal 2D BiI 3 on mica substrate via a cooling-induced growth method is reported, with the thickness of 8 ∼ 1000 nm and a lateral dimension of 110 ∼ 1000 μm. X-ray diffraction and selected area electron diffraction demonstrate the single crystal nature of 2D BiI 3 flakes. The high temperature during heat preservation step prevents the deposition of BiI 3 vapor, and then, when proceeding to cooling-induced growth step, single crystal 2D BiI 3 flakes start to nucleate on colder mica substrate and grow up to ∼ 1000 μm (lateral dimension) rapidly. The stability test indicates the 2D BiI 3 flake decomposes with the present of both O 2 and water. Finally, the cooling rate, height of crucible, holding temperature and type of substrate have also been investigated to show the structural evolution of 2D BiI 3 flakes.
Two-dimensional (2D) metallic 1T-CoTe 2 has attracted considerable attention due to its fascinating physical properties and promising applications in electronics and catalysis. However, the production of high-quality 2D 1T-CoTe 2 still remains challenging. Herein, we demonstrate a methodology to realize the facile synthesis of ultrathin, high-quality CoTe 2 flakes with a thickness down to 2.3 nm on mica substrates by an ambient-pressure chemical vapor deposition (CVD) technique. The atomic arrangement is verified by scanning transmission electron microscopy. The theoretical calculations uncover the metallic characteristic of 1T-CoTe 2 in the 2D limit. Remarkably, the CVD-derived 2D metallic CoTe 2 flakes for the hydrogen evolution reaction (HER) catalyst exhibit admirable performance, such as an overpotential of 186 mV at 10 mA·cm −2 , a Tafel slope of 78 mV·dec −1 , an exchange current density of 69 μA·cm −2 , and negligible performance degradation after 1000 cycles. These results establish novel approaches for the synthesis and HER application of 2D metallic 1T-CoTe 2 . Graphical abstract
危险品化学品经营许可证（带存储）