Phase Transformation From Amorphous to Crystalline in MoS₂ Nanosheets Prepared via Desulfurization of MoS₃: Investigation of Optical and Structural Properties

ABSTRACT This study reports the synthesis of amorphous and polycrystalline molybdenum disulfide (MoS 2 ) nanostructures. Amorphous MoS 2 nanoparticles were synthesized by desulfurizing MoS 3 under hydrazine vapor at 360°C. Polycrystalline nanosheets were obtained by annealing at 800°C. For comparison, crystalline MoS 2 nanoparticles were also synthesized via a hydrothermal method. The structural and optical properties were characterized using X‐ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy‐dispersive X‐ray spectroscopy (EDX), photoluminescence (PL), and UV‐visible spectroscopy. UV‐visible analysis revealed a decrease in the bandgap energy from approximately 2.4 to 2.0 eV, attributed to the change in synthesis method. Annealing significantly influenced the crystallographic and optical properties of MoS 2 . The initial desulfurized MoS 3 sample exhibited an amorphous structure, while both the annealed and hydrothermally prepared samples showed a polycrystalline structure.