Electronic Modulation of Doped MoS₂ Nanosheets for Improved CO₂ 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 CO₂ sensing, due to their weak CO₂ adsorption capacity. Herein, we predict through density functional theory (DFT) calculations that rare earth metal doping is an effective strategy to boost the CO₂ 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 MoS₂. When negative charges are injected in rare earth metal doped MoS₂ (R-MoS₂), the 5d or 4f orbital of the rare earth metal atom in R-MoS₂ can produce a stronger orbital hybridization with 2p orbitals of C and O in CO₂. Therefore, the CO₂ adsorption is significantly enhanced and the charge transfer is facilitated for negatively charged R-MoS₂. Moreover, negatively charged R-MoS₂ exhibits an excellent CO₂ selectivity. Our results indicate that the rare earth metal doping and electronic modulation in 2D materials may provide a new pathway for CO₂ sensing and capture.