Adsorption of ethylene oxide on doped monolayers of MoS2: A DFT study

Highlights: • Pristine MoS₂ is chemically inert toward ethylene oxide (EO). • Ti, Ni, Pd, Si and Ge doping has a large impact on the size of the band gap of MoS₂. • Ti, Ni, Pd, and Si doping facilitate a strong bonding interaction with EO. • The band gaps of Ti and Si doped MoS₂ are shown sensitive toward adsorption of EO. • The change of the band gap is large, which should make the adsorption detectable. Density functional theory (DFT) calculations have been performed to investigate the doping of Ti, Ni, Pd, Si, Ge, P, and Cl atoms into an S-vacancy of MoS₂ monolayer, and its impact on the sensitivity toward ethylene oxide (EO). The results show that, pristine MoS₂ is chemically inert toward EO, however, Ti, Ni, Pd, and Si doping facilitates a stronger binding with the molecule, and an enhanced charge transfer sufficient for detection. Furthermore, the electronic band gap of Ti, and Si doped MoS₂ is shown sensitive toward EO, experiencing a 0.26 eV (22%) and 0.85 eV (51%) change upon adsorption, which suggests a second mode of detection. The investigation also illustrates that, in order to achieve stronger binding and adsorption-sensitive band gap the d-block doped MoS₂ requires a strong $p_z/d_z^2$ hybridization, while p-block doped layer requires an activation of the s subshell of the dopant.