1T/2H-MoS2 engineered by in-situ ethylene glycol intercalation for improved toluene sensing response at room temperature

Molybdenum sulfide (MoS2) was engineered by intercalation of ethylene glycol to form 2H (semiconductor) and 1T (metallic) phases. MoS2 was successfully synthesized under solvothermal conditions with different solvents. Water, ethylene glycol (EG), and a mixture of water and EG were used as the solvent. The obtained samples were denoted as MoS2 (W), MoS2 (EG), and MoS2 (EG:W), respectively. The use of ethylene glycol as a solvent expands the (0 0 2) lattice spacing which indicated the expansion of interlayer spacing by intercalation of EG through solvothermal reaction. The MoS2 intercalated with EG possessed higher 1T phase compared to MoS2 without any intercalation. The obtained MoS2 was applied for room temperature toluene sensing with different relative humidity (RH, 20, 40, 60, 80%). The increase of relative humidity could continuously increase the base resistance and also the sensing response of MoS2 (W) and MoS2 (EG:W). For MoS2 (EG), 60% relative humidity showed the optimum condition for sensing applications. The all MoS2 (W), MoS2 (EG), and MoS2 (EG:W) had good sensing performance at 60% RH with sensing ability (ΔR/Rair%) in 100 ppm toluene around 12.50, 14.53, 16.29%, respectively. 1T-MoS2 is taking a major contribution on the sensing properties of MoS2.