Electronic Modulation of Doped MoS Nanosheets for Improved CO Sensing and Capture.

Transition-metal dichalcogenides (TMDs) are widely used in the gas sensing field, owing to their high surface-to-volume ratio enabled by the two-dimensional (2D) structure, adjustable band gap, and high electron transfer. However, it is challenging for TMD materials to realize superior CO sensing, due to their weak CO adsorption capacity. Herein, we predict through density functional theory (DFT) calculations that rare earth metal doping is an effective strategy to boost the CO sensing capability of TMDs. As a proof-of-concept, we investigate and find that the introduction of rare earth metal atoms (La, Ce, Pr, or Nd) can induce lattice strain and modulate the electronic properties of MoS. When negative charges are injected in rare earth metal doped MoS (R-MoS), the 5d or 4f orbital of the rare earth metal atom in R-MoS can produce a stronger orbital hybridization with 2p orbitals of C and O in CO. Therefore, the CO adsorption is significantly enhanced and the charge transfer is facilitated for negatively charged R-MoS. Moreover, negatively charged R-MoS exhibits an excellent CO selectivity. Our results indicate that the rare earth metal doping and electronic modulation in 2D materials may provide a new pathway for CO sensing and capture.