Effects of Precursor Concentration on Dimensional Size, Defect State, and Gas Sensing Performance of MoS₂ Sheets Synthesized by Hydrothermal Method

The objective of this study is to investigate effects of precursor concentration on dimensional size, defect state, and gas sensing performance of MoS₂ sheets synthesized by hydrothermal method with various precursor concentrations (0.14–1.4 m) in fixed HCl solution (7 m). The MoS₂ sheets show a defect-rich and strained structure. When precursor concentration is increased, dimensional size of the sheet is increased while the specific surface area of the sheet is decreased. The MoS₂ sensor made with 0.14 m precursor solution exhibits superior sensing performance with high sensitivity (372%) and rapid recovery time (<16 min) at room temperature in a 500 ppm NO₂ gas atmosphere due to enhanced active site resulting from the highest specific surface area. In addition, all MoS₂ samples show a complete recovery after response to NO₂ gas probably related to the defective and strained surface resulting from the use of HCl surfactant.