Exploring hydrothermal temperature variations in MoS2 structure synthesis for enhanced structural and electrochemical properties in hydrogen evolution reaction

The hexagonal structured of Molybdenum disulfide (MoS₂) material demonstrates potential for energy storage and catalysis applications because of its distinctive layered structure and electrochemical properties. The synthesized MoS₂ using hydrothermal methods at varying temperatures before completing a thorough characterization of its structural and electrochemical properties. The X-ray diffraction (XRD) analysis verified that the synthesized MoS₂ existed in a crystalline state. The XRD data matched the reference pattern from JCPDS database (No. 00–037–1492) which validated the successful production of hexagonal MoS₂. The hexagonal structure of MoS₂ consists of alternating molybdenum and sulfur atom layers which delivers intrinsic benefits including extensive surface area and adjustable electronic characteristics along with wide interlayer gaps. The electrochemical properties of materials depend heavily on their crystalline structure which requires essential confirmation. The cyclic voltammetry analysis of synthesized MoS₂ showed a characteristic "flag pattern" which demonstrated reversible electrochemical charge and discharge behavior. The MoS₂ sample synthesized at 220 °C exhibited the best performance among the synthesized materials at different temperatures. The specific capacitance reached 8.70 × 10⁻² F/g in this sample which demonstrated improved energy storage capabilities. The optimized morphology and crystallinity achieved at this synthesis temperature allows efficient ion diffusion and charge storage which results in superior specific capacitance. Linear sweep voltammetry measurements showed that MoS₂ synthesized at 220 °C demonstrated excellent hydrogen evolution reaction (HER) activity. The assessment of material catalytic efficiency in electrochemical water splitting applications requires evaluation of HER activity. Higher performance of HER at 220°C stems from two factors: better exposure of active edge sites and material conductivity enhancement which reduce the energy barrier for hydrogen evolution. The EIS analysis provided insights into the charge-transfer dynamics of the synthesized MoS₂ samples. The sample prepared at 220 °C exhibited a low charge-transfer resistance (R ct ) of 403 Ω, indicating efficient electron transport at the electrode-electrolyte interface. A lower R ct is crucial for high-performance energy storage and catalytic applications because it minimizes energy losses during charge transfer. The combination of high HER activity and low R ct suggests that MoS₂ synthesized at this temperature possesses an optimal balance of conductivity and active site availability.