Unravelling the physisorption characteristics of H₂S molecule on biaxially strained single-layer MoS₂

Sensing ultra-low levels of toxic chemicals such as H₂S is crucial for many technological applications. In this report, employing density functional theory (DFT) calculations, we shed light on the underlying physical phenomena involved in the adsorption and sensing of the H₂S molecule on both pristine and strained single-layer molybdenum disulfide (SL-MoS₂) substrates. We demonstrate that the H₂S molecule is physisorbed on SL-MoS₂ for all values of strain, i.e. from -8% to +8%, with a modest electron transfer, ranging from 0.023e^- to 0.062e^-, from the molecule to the SL-MoS₂. According to our calculations, the electron-donating behaviour of the H₂S molecule is halved under compressive strains. Moreover, we calculate the optical properties upon H₂S adsorption and reveal the electron energy loss (EEL) spectra for various concentrations of the H₂S molecule which may serve as potential probes for detecting H₂S molecules in prospective sensing applications based on SL-MoS₂.