Synthesis of molybdenum diselenide nanosheets and its ethanol-sensing mechanism

Molybdenum diselenide (MoSe2) nanosheets thin film gas sensor was firstly fabricated and its sensing potential to ppm-level ethanol vapor at low operating temperature was investigated. Ultrathin MoSe2 nanosheets were prepared in large scale through a facile liquid-phase exfoliation method using low-boiling-temperature solvent. The exfoliated MoSe2 nanosheets exhibited high purity and crystallinity with few atomic layer thickness. Systematical gas sensing tests demonstrated that MoSe2 nanosheets based thin film could be utilized as ethanol gas sensor with linear response, quick recovery, and good repeatability at 90 °C. The sensing mechanism of MoSe2 toward ethanol was investigated based on first principle calculation. The adsorption behavior of ethanol molecules on MoSe2 surface was revealed in light of adsorption orientation, adsorption energy, charge transfer, projected electronic density of state, and molecular orbital. The calculation well matched with experimental results. It is found the quick and completed recovery of MoSe2 nanosheets sensor was benefited by the appropriate physical interaction between ethanol and MoSe2 surface. This finding offers a competitive option instead of conventional graphene sensor for ethanol gas detection at low temperature.