Understanding the Highly Selective Methanol Sensing Mechanism of Electrodeposited Pristine MoS2 Using First Principle Analysis

In this paper, synthesis, characterizations and highly selective methanol sensing performance of pristine electrodeposited MoS ₂ thin film is reported and correlated with the corresponding density functional theory (DFT) based computations. Pristine MoS ₂ was electrochemically deposited on conducting Indium doped Tin Oxide (ITO) glass substrate, and was annealed at three different temperatures viz. 350 °C, 450 °C and 550 °C. Sensing study was performed targeting primary alcohols i.e. methanol, ethanol, and 2-propanol. At room temperature (27 °C), pristine MoS ₂ annealed at 550 °C, was found to offer the most promising sensing performance with a response magnitude of ~17% (160%) with an appreciably high selectivity window (with the nearest interfering species ethanol) of 18% (78%) towards 10 ppm (400 ppm) of methanol. Adsorption mechanism was investigated with the help of DFT based simulation studies in terms of changes in structural (adsorption distances) and energetic (adsorption energies) features of MoS ₂ considering the adsorption of alcohol molecules on the same. Simulation results revealed that MoS ₂ offered enormous potential in terms of adsorption energy (~20 times) and the shortest adsorption distance (~1.2 times) for methanol compared to its nearest interfering species (ethanol), justifying the present experimental outcome.