Synthesis of high-crystalline ReS2 monolayers by sodium-assisted chemical vapor deposition

Featured with highly structural anisotropy, rhenium-based transition metal dichalcogenides (TMDs) and alloys have attracted significant attention in electronics, optoelectronics, energy storage, and catalysis. The controlled growth of large-area, high-quality anisotropic TMDs is critical for associated applications. However, the Jahn-Teller effect and Peierls distortion of the lattice easily induce out-of-plane growth, making it a challenge to prepare uniform-thickness Re-based TMDs. Here, we report a NaCl-assisted chemical vapor deposition strategy for Re-based TMDs and highlight the essential role of Na+ absorption based on a combination of experiments and density functional theory calculations. We found that Cl has little influence on the intermediate products during the reaction process, while Na is responsible for reducing the highest energy barrier required for the formation of Re-Re chains. The barrier for the rate-determining step is reduced by 0.325 eV compared to that without considering Na+ adsorption. Additionally, the field-effect transistor device based on the sodium-assisted synthesized ReS2 monolayer demonstrates superior electrical properties. Our findings not only provide a reliable experimental scheme for the preparation of Re-based semiconductors but also promote the application of ReS2 in high-performance electronics.