Vapor Transport Synthesis of Two-Dimensional SnS₂ Nanocrystals Using a SnS₂ Precursor Obtained from the Sulfurization of SnO₂

Manufacturing high-quality, two-dimensional (2D), layered materials with crystal-growth techniques is an important challenge for the advancement of 2D communication technologies. In this study, a simple method was developed for synthesizing 2D nanocrystals based on the model system of SnS₂. The method involves the sulfurization of a metal oxide to a metal chalcogenide, which subsequently acts as a source of vapors for the growth of 2D crystals. The effect of the annealing conditions on the thermal sulfurization of SnO₂ powder was investigated. The results showed that pure SnS₂ powder could be obtained in a N₂ atmosphere at 700 °C. SnS₂ nanocrystals were successfully synthesized from the as-prepared SnS₂ powder by the vapor transport method. The synthesized SnS₂ nanocrystals had a 2D layered structure with hexagonal symmetry and exhibited typical n-type semiconducting characteristics, with an optical band gap of 2.05 eV. This novel method, which uses a preferentially prepared source for vapor transport, could provide a simple way to synthesize new types of 2D layered materials. This is because it only requires the volatilization of a source and subsequent condensation to a single crystal for the growth of 2D materials, with no complex chemical reactions occurring during vapor transport.