Adsorption of formaldehyde on transition metal doped monolayer MoS₂ : A DFT study

Density functional theory (DFT) calculations have been performed to investigate the electronic properties of pristine monolayer MoS₂ and various transition-metal (TM) (Ni, Pt, Ti and Pd) doped MoS₂ as well as the adsorption of formaldehyde on these monolayer 2D structures. It was found that the CH₂O adsorption energy (0.11eV) on monolayer MoS₂ was very weak, indicating that pristine MoS₂ is insensitive to formaldehyde (CH₂O). However, the adsorption of CH₂O on monolayer TM-MoS₂ shows relatively high affinity. Thus, TM-doping can substantially improve the sensitivity towards CH₂O. In order to investigate the mechanism of adsorption, the electronic properties such as molecular projected density of states and differential charge transfer were calculated. The results showed that the adsorption on Ti-doped monolayer MoS₂ (1.59 eV) is very promising with the most stable adsorption. Both differential charge transfer and ab initio molecular dynamic were used to investigate the adsorption mechanism. The ab initio molecular dynamic at 500 K was performed using the Car-Parrinello method. The most stable configuration shows the highest adsorption energy and CH₂O can be adsorbed even at 500 K. These suggest that Ti-doped monolayer MoS₂ would be a feasible material for CH₂O removal at room temperature.