MoSe 2 nanosheets for detection of methanol and ethanol vapors: A DFT study.

We report the adsorption properties of methanol (ML) and ethanol (EL) vapor molecules on to the monolayer MoSe2 surface. Before, studying the adsorption behavior, the structural stability of MoSe2 monolayer is ensured with formation energy. The stable monolayer MoSe2 nanosheet is used as a base material for the adsorption of ML and EL vapor molecules. The interaction of ML and EL vapors on MoSe2 surface layer is explored using the adsorption energy, energy gap variation and Bader charge analysis. We noticed the band gap variation between 1.43 and 1.88 eV upon adsorption of methanol and ethanol vapors on to MoSe2 nanosheets. Also the adsorption energy is found in the range of -0.375 to -0.732 eV upon the interaction of alcohol molecules on MoSe2 flakes. Besides, the density of states (DOS) spectrum and electron density clearly envisions the adsorption properties of ML and EL vapors on to the MoSe2 monolayers. Furthermore, a short recovery time is noticed for MoSe2 nanosheet material upon desorption of methanol and ethanol molecules. Moreover, the variation in the resistance of MoSe2 base material is noticed upon adsorption of ML and EL molecules. The findings show that monolayer MoSe2 nanosheets can be used as a chemi-resistance to detect the presence of ML and EL vapors in the environment.